Quantum bit state measurement method and apparatus, electronic device, computer-readable storage medium and computer program product

Abstract

A quantum bit state measurement method and apparatus, an electronic device, and a storage medium. The method comprises: acquiring first measurement probabilities respectively corresponding to a plurality of candidate quantum bit strings; deleting part of the candidate quantum bit strings from the plurality of candidate quantum bit strings according to the first measurement probabilities, and determining the remaining candidate quantum bit strings as target quantum bit strings, the first measurement probabilities being obtained by performing state measurement on a quantum bit circuit, the quantum bit circuit comprising a plurality of first quantum bits, and the candidate quantum bit strings comprising a state of each first quantum bit; creating a plurality of first initial quantum bit strings on the basis of the plurality of target quantum bit strings, and acquiring a first correction matrix obtained by performing error syndrome measurement on the plurality of first initial quantum bit strings; acquiring a probability to be corrected corresponding to each target quantum bit string, said probability being a measurement probability obtained by performing multiple state measurement again on the quantum bit circuit; and, according to the first correction matrix, respectively correcting the plurality of probabilities to be corrected, so as to obtain a target probability corresponding to each target quantum bit string.

Description

Quantum bit state measurement method, device, electronic device, computer-readable storage medium, and computer program product

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The embodiments of this application are based on and claim the priority of Chinese patent application with application number 202410068643.3 and application date January 17, 2024. The entire contents of the Chinese patent application are hereby introduced into the embodiments of this application as a reference. Technical Field

[0003] The present application relates to the field of computer technology, and in particular to a quantum bit state measurement method, device, electronic device, computer-readable storage medium, and computer program product. Background Art

[0004] Currently, one of the key factors limiting the development of quantum computers is errors generated during quantum computing. Errors occur during qubit state measurements, with high error rates and a significant impact on computational results. When measuring the state of a qubit, factors such as noise and interference can cause the measurement result to be inconsistent with the qubit's actual state. This error can distort the computational results and limit the reliability and accuracy of quantum computers. To address this, measurement results must be corrected. However, with a large number of qubits, the resource consumption for correction increases significantly, reducing the efficiency of state measurement. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail in this application. This overview is not intended to limit the scope of protection of the claims.

[0006] The embodiments of the present application provide a quantum bit state measurement method, device, electronic device, computer-readable storage medium, and computer program product, which reduce the resource consumption of correction and thus effectively improve the efficiency of state measurement.

[0007] The present invention provides a method for measuring the state of a quantum bit, which is applied to an electronic device and includes:

[0008] Obtaining first measurement probabilities corresponding to a plurality of candidate qubit strings, respectively; deleting some of the candidate qubit strings from the plurality of candidate qubit strings based on the first measurement probabilities; and determining the remaining candidate qubit strings as target qubit strings, wherein the first measurement probabilities are obtained by performing a state measurement on a qubit circuit, the qubit circuit including a plurality of first qubits, and the candidate qubit strings including states of each of the first qubits;

[0009] Creating a plurality of first initial qubit strings based on the plurality of target qubit strings, and obtaining a first correction matrix obtained by performing error survey based on the plurality of first initial qubit strings;

[0010] Obtaining a probability to be corrected corresponding to each target qubit string, wherein the probability to be corrected is a measurement probability obtained by performing multiple state measurements on the qubit circuit;

[0011] The plurality of probabilities to be corrected are corrected respectively according to the first correction matrix to obtain target probabilities corresponding to the respective target quantum bit strings.

[0012] The present application also provides a quantum bit state measurement device, including:

[0013] a first processing module configured to obtain first measurement probabilities corresponding to a plurality of candidate qubit strings, delete some of the candidate qubit strings from the plurality of candidate qubit strings based on the first measurement probabilities, and determine the remaining candidate qubit strings as target qubit strings, wherein the first measurement probabilities are obtained by performing a state measurement on a qubit circuit, the qubit circuit including a plurality of first qubits, and the candidate qubit strings including states of each of the first qubits;

[0014] A second processing module is configured to create a plurality of first initial qubit strings based on the plurality of target qubit strings, and obtain a first correction matrix obtained by performing error survey based on the plurality of first initial qubit strings;

[0015] an acquisition module configured to acquire a probability to be corrected corresponding to each of the target qubit strings, wherein the probability to be corrected is a measurement probability obtained by performing multiple state measurements on the qubit circuit;

[0016] The correction module is configured to correct the multiple probabilities to be corrected respectively according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string.

[0017] An embodiment of the present application further provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the above-mentioned quantum bit state measurement method when executing the computer program.

[0018] An embodiment of the present application further provides a computer-readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the above-mentioned quantum bit state measurement method.

[0019] The present application also provides a computer program product, comprising a computer program stored in a computer-readable storage medium. A processor of a computer device reads the computer program from the computer-readable storage medium and executes the computer program, causing the computer device to implement the aforementioned quantum bit state measurement method.

[0020] The embodiments of the present application include at least the following beneficial effects: by obtaining the first measurement probability corresponding to each candidate quantum bit string, deleting some candidate quantum bit strings according to the first measurement probability, and determining the remaining candidate quantum bit strings as the target quantum bit strings, at this time, relative to the deleted part of the candidate quantum bit strings, the target quantum bit string is the quantum bit string that contributes to the measurement result, and accordingly, when creating multiple first initial quantum bit strings based on multiple target quantum bit strings, the number of first initial quantum bit strings created based on candidate quantum bit strings can be reduced, so that when obtaining the first correction matrix obtained by error survey based on multiple first initial quantum bit strings, the dimension of the first correction matrix is ​​reduced, and therefore, the probability to be corrected corresponding to each target quantum bit string is subsequently obtained, and the multiple probabilities to be corrected are corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string, so that subsequent processing is performed based on the first correction matrix with reduced dimension, which can reduce the resource consumption of correction under the premise of correcting the state measurement result of the quantum bit, and effectively improve the efficiency of state measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0022] FIG1 is a schematic diagram of an implementation environment provided by an embodiment of the present application;

[0023] FIG2 is a schematic diagram of a flow chart of a method for measuring the state of a quantum bit provided in an embodiment of the present application;

[0024] FIG3 is a spatial schematic diagram of the probability distribution of the state of a quantum bit provided in an embodiment of the present application;

[0025] FIG4 is a columnar schematic diagram of the distribution of quantum bit reading results provided in an embodiment of the present application;

[0026] FIG5 is another columnar schematic diagram of the distribution of quantum bit reading results provided in an embodiment of the present application;

[0027] FIG6 is a bar graph showing an error rate according to an embodiment of the present application;

[0028] FIG7 is a schematic diagram of a curve of measurement accuracy provided by an embodiment of the present application;

[0029] FIG8 is another schematic diagram of a curve showing measurement accuracy according to an embodiment of the present application;

[0030] FIG9 is a schematic diagram of an architecture of a method for measuring the state of a quantum bit provided in an embodiment of the present application;

[0031] FIG10 is a columnar schematic diagram of the measurement probability corresponding to the target quantum bit string in the first state provided by an embodiment of the present application;

[0032] FIG11 is a columnar schematic diagram of the measurement probability corresponding to the target quantum bit string in the second state provided by an embodiment of the present application;

[0033] FIG12 is a broken line diagram of the Pauli operator Z corresponding to different measurement methods provided in an embodiment of the present application;

[0034] FIG13 is a broken line diagram of an expected value corresponding to the Pauli operator X provided in an embodiment of the present application;

[0035] FIG14 is a broken line diagram of an expected value corresponding to the Pauli operator Y provided in an embodiment of the present application;

[0036] FIG15 is a broken line diagram of the expected value corresponding to the Pauli operator Z provided in an embodiment of the present application;

[0037] FIG16 is a schematic structural diagram of a quantum bit state measurement device provided in an embodiment of the present application;

[0038] FIG17 is a partial structural block diagram of a terminal provided in an embodiment of the present application;

[0039] FIG18 is a partial structural block diagram of the server provided in an embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0041] It should be noted that, in each specific embodiment of the present application, when it comes to the need to perform relevant processing based on data related to the characteristics of the target object such as target object attribute information or attribute information set, the permission or consent of the target object will be obtained first, and the collection, use and processing of these data will comply with relevant laws, regulations and standards. Among them, the target object can be a user. In addition, when the embodiment of the present application needs to obtain target object attribute information, the target object's separate permission or separate consent will be obtained by means of a pop-up window or jumping to a confirmation page. After clearly obtaining the target object's separate permission or separate consent, the necessary target object-related data for enabling the normal operation of the embodiment of the present application will be obtained.

[0042] In the embodiments of the present application, the term "module" or "unit" refers to a computer program or a part of a computer program that has a predetermined function and works together with other related parts to achieve a predetermined goal, and can be implemented in whole or in part by using software, circuits (such as processing circuits or memories), or a combination thereof. Similarly, a processor (or multiple processors or memories) can be used to implement one or more modules or units. In addition, each module or unit can be part of an overall module or unit that includes the function of the module or unit.

[0043] To facilitate understanding of the technical solutions provided in the embodiments of the present application, some second terms used in the embodiments of the present application are explained here:

[0044] Quantum computing: Quantum computing is a computing method designed using the principles of quantum mechanics. Its key difference from traditional computing is that it uses quantum bits (qubits) rather than traditional binary bits for calculations. Qubits have distinct properties from traditional binary bits, the most important of which is that they can simultaneously exist in multiple (or at least two) states. This ability to represent two states simultaneously allows qubits to carry more information, allowing the same number of qubits to perform more computations than classical computing. Therefore, quantum computers significantly increase computer processing speed.

[0045] A qubit is the fundamental unit of information in quantum computing. While its role in quantum computing is similar to that of a bit in traditional computing, its behavior differs significantly. While a classical bit is binary and can only store a 0 or 1, a qubit can store a superposition of all possible states—a state of |0> and a state of |1>—thus significantly increasing computer processing speed.

[0046] Superposition: As mentioned above, a qubit can represent two states simultaneously. Therefore, a qubit exists in two states simultaneously, a superposition of the two states. While in superposition, a qubit can represent all possible combinations of states. The state of a qubit continues to fluctuate until it is observed and measured.

[0047] Collapse: Before being observed, a qubit represents a superposition of all possible states. This means that the qubit's state fluctuates continuously. When observed, the qubit becomes fixed in one state, a process called collapse. After measurement, the qubit represents either state |0> or state |1>, rather than a superposition.

[0048] Entanglement: Entanglement is a phenomenon in quantum mechanics in which a unique correlation forms between multiple quantum bits (qubits), making it impossible to describe the state of each qubit individually; the quantum state of the qubits must be considered as a whole. When multiple qubits are entangled (i.e., multiple qubits are in an entangled state), they form a system and influence each other. Measuring the state of one qubit instantly affects the states of the other entangled qubits, regardless of the distance between them. This phenomenon transcends any locality principle in classical physics, allowing the measurement of one qubit to infer information about other qubits. By adding more entangled qubits to the system, quantum computers can solve more complex problems.

[0049] Currently, one of the key factors limiting the development of quantum computers is errors generated during quantum computing. Errors occur during qubit state measurements, with high error rates and a significant impact on computational results. When measuring the state of a qubit, factors such as noise and interference can cause the measurement result to be inconsistent with the qubit's actual state. This error can distort the computational results and limit the reliability and accuracy of quantum computers. To address this, measurement results must be corrected. However, with a large number of qubits, the resource consumption for correction increases significantly, reducing the efficiency of state measurement.

[0050] Based on this, the embodiments of the present application provide a quantum bit state measurement method, device, electronic device and storage medium, which reduce the resource consumption of correction and thus effectively improve the efficiency of state measurement.

[0051] 1 , which is a schematic diagram of an implementation environment provided in an embodiment of the present application, wherein the implementation environment includes a quantum computer 101 .

[0052] Exemplarily, the quantum computer 101 can obtain a first measurement probability corresponding to each candidate quantum bit string, delete invalid candidate quantum bit strings according to the first measurement probability (invalid candidate quantum bit strings are part of the candidate quantum bit strings determined from multiple candidate quantum bit strings through the first measurement probability), and determine the remaining candidate quantum bit strings as target quantum bit strings, wherein the first measurement probability is obtained after performing multiple state measurements on the quantum bit circuit, the quantum bit circuit includes multiple first quantum bits, and the candidate quantum bit string includes the state of each first quantum bit; create multiple first initial quantum bit strings based on the multiple target quantum bit strings, and obtain a first correction matrix obtained by error survey based on the multiple first initial quantum bit strings; obtain the probability to be corrected corresponding to each target quantum bit string, wherein the probability to be corrected is obtained after performing multiple state measurements on the quantum bit circuit again; correct the multiple probabilities to be corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string; the quantum computer 101 can obtain an observable quantity, multiply the observable quantity with the corresponding target probability, and calculate the average value, and use the average value as the expected value under a given quantum state. In physics, an observable is a physical quantity that can be measured through experiment or observation. An observable is a fundamental concept in both quantum mechanics and classical physics. An observable can be a property of a system, such as position, velocity, energy, momentum, or charge, or it can be a characteristic of a physical process, such as the decay rate or intensity of light. In quantum mechanics, observables correspond to operators, with each observable represented by an operator that performs a measurement on a quantum state.

[0053] The quantum computer 101 obtains the first measurement probability corresponding to each candidate quantum bit string, deletes some candidate quantum bit strings according to the first measurement probability, and determines the remaining candidate quantum bit strings as the target quantum bit strings. At this time, relative to the deleted candidate quantum bit strings, the target quantum bit string is the quantum bit string that contributes to the measurement result. Accordingly, when creating multiple first initial quantum bit strings based on multiple target quantum bit strings, the number of first initial quantum bit strings created based on candidate quantum bit strings can be reduced, so that when obtaining the first correction matrix obtained by error survey based on multiple first initial quantum bit strings, the dimension of the first correction matrix is ​​reduced. Therefore, the probability to be corrected corresponding to each target quantum bit string is subsequently obtained, and the multiple probabilities to be corrected are corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string. Subsequent processing is performed based on the first correction matrix with reduced dimension, which can reduce the resource consumption of correction while correcting the state measurement result of the quantum bit, and effectively improve the efficiency of state measurement.

[0054] The method provided in the embodiments of the present application can be applied to various scenarios, including but not limited to cloud technology, quantum computing, smart transportation, assisted driving and other scenarios.

[0055] Referring to Figure 2, Figure 2 is a flow chart of a quantum bit state measurement method provided in an embodiment of the present application. The quantum bit state measurement method can be executed by a server, or by a terminal, or by a server in cooperation with a terminal. The state measurement method includes but is not limited to the following steps 201 to 204.

[0056] Step 201: Obtain first measurement probabilities corresponding to multiple candidate quantum bit strings respectively, delete some candidate quantum bit strings from the multiple candidate quantum bit strings based on the first measurement probabilities, and determine the remaining candidate quantum bit strings as target quantum bit strings.

[0057] The first measurement probability is obtained by performing multiple state measurements on the qubit circuit. For example, multiple state measurements are performed on the qubit circuit to obtain corresponding measurement results, with each measurement result corresponding to one state measurement. The multiple measurement results corresponding to these multiple state measurements are statistically analyzed to obtain the first measurement probabilities corresponding to each of the candidate qubit strings. The qubit circuit includes multiple first qubits (i.e., a type of qubit), and the candidate qubit strings include the states of each first qubit. Any first qubit is a two-level system. In a two-level system, the lower energy state can be represented as the |0> state, and the higher energy state as the |1> state. A two-level system has only two possible energy levels, known as the ground state and the excited state. In a qubit, these two energy levels can correspond to the logical states |0> and |1>, respectively. The |0> state represents the qubit's ground state, the lowest energy state, while the |1> state represents the qubit's excited state, the higher energy state. This two-level structure enables qubits to be used to store and represent information, similar to bits in classical computing. However, unlike classical bits, qubits can exist simultaneously in a superposition of the |0> and |1> states, enabling parallel processing in quantum computing. These two energy levels may manifest differently in different physical systems. For example, in optical systems, the |0> and |1> states may represent two orthogonal polarization states of a photon; in superconducting qubits, the |0> and |1> states may represent two different states of current flow; and in trapped ion systems, the |0> and |1> states may represent different energy levels of the electrons within an ion.

[0058] State measurement refers to quantum measurement. In quantum mechanics, quantum measurement is the process of observing a quantum circuit to obtain specific properties. Quantum circuits can be divided into single-qubit circuits and multi-qubit circuits. Single-qubit circuits handle operations on a single qubit, while multi-qubit circuits handle interactions and entanglement between multiple qubits. Unlike measurements in classical physics, quantum measurement involves the collapse of a quantum state. During the measurement process, the state of the qubit collapses to a specific measurement result (i.e., a definite state, such as the |0> state or the |1> state). The result of a quantum measurement is given in the form of probabilities. Due to the statistical properties of quantum mechanics, the probability of different measurement results is related to the amplitude of the qubit's wave function. The measurement result projects the qubit's wave function, placing the qubit in the specific state corresponding to the measurement result. Quantum measurement is the foundation of quantum information processing and quantum computing. Quantum measurement can be used to obtain information about qubits and to manipulate and transmit them in quantum algorithms and quantum communications. The properties and laws of quantum measurement are one of the important research areas in quantum mechanics.

[0059] The single-qubit circuit is described in detail below.

[0060] A single-qubit circuit contains a single first qubit. The wave function of the single-qubit circuit is as shown in formula (1): |ψ>=α|0>+β|1> (1)

[0061] Where |ψ> is the quantum state of the first quantum bit (i.e., state), α and β are both complex numbers, and α and β satisfy the normalization condition: |α| 2 +|β| 2 = 1, and both the |0> and |1> states are eigenstates of the first qubit. In quantum mechanics, when the qubit's Hamiltonian (an operator describing the energy properties of a quantum system) acts on the qubit's state, the state remains unchanged but is multiplied by a constant called the eigenvalue, and the resulting state is called an eigenstate. In a qubit, there are two types of eigenstates: 1) the ground eigenstate (|0> state), which corresponds to the lowest energy state; and 2) the excited eigenstate (|1> state), which corresponds to a higher energy state. State measurements on qubit circuits can be divided into the following three cases.

[0062] Case 1: When β = 0, the first qubit is in the |0> state. After the state measurement, the first qubit will remain in the |0> state. The wave function can be used to determine that the probability of the state measurement result being the |0> state is 1, and the probability of the state measurement result being the |1> state is 0.

[0063] Case 2: When α = 0, the first qubit is in the |1> state. After the state measurement, the first qubit will remain in the |1> state. The wave function can be used to determine that the probability of the state measurement result being the |1> state is 1, and the probability of the state measurement result being the |1> state is 0.

[0064] Case 3: When α≠0 and β≠0, the first qubit is in a superposition of two eigenstates. After the state is measured, the superposition state collapses to one of the two eigenstates, that is, the |ψ> state can collapse to the |0> state or the |1> state. The probability that the state measurement result is the |0> state can be determined by the wave function is |α| 2 , the probability that the state measurement result is the |1> state is |β| 2 .

[0065] For example, the first qubit in the same |ψ> state can be prepared multiple times, or multiple first qubits in the same |ψ> state can be prepared. Then, through multiple state measurements, the measurement probability that the state measurement result is the |0> state is determined, that is, |α| 2 The estimated value of , and the probability of determining the state measurement result as the |1> state, that is, |β| 2 estimated value.

[0066] Refer to Figure 3, which is a spatial schematic diagram of the probability distribution of the state of a quantum bit provided in an embodiment of the present application.

[0067] Among them, Figure 3 shows the probability distribution of a single photon in two distribution cases in the phase-amplitude space (PQ space). In quantum optics, the PQ space is a geometric space used to describe the state of a photon. Due to the uncertainty relationship, the probability distribution of a single photon in the PQ space is two Gaussian distributions. The probability distribution areas of the two states overlap. In the overlapping area, it is difficult to distinguish the state of the photon, making p(0|1) and p(1|0) in the same order of magnitude. p(0|1) refers to the probability that a photon in the |1> state is mistakenly measured as being in the |0> state, and p(1|0) refers to The probability that a photon in the |0> state is mistakenly measured as being in the |1> state; compared with the distribution on the left side of Figure 3, in the distribution on the right side of Figure 3, due to the limited lifetime of the quantum bit or the long measurement time, the overlapping area of ​​the probability distribution of the two states is larger, making it more difficult to distinguish the state of the photon, and the system is inevitably subject to external interference. Taking the system and the external environment as a whole as the research objects, according to the Heisenberg motion equation of the open system, the probability of the two-level system transitioning from the |1> state to the |0> state is greater, and the p(0|1) caused by this mechanism is much larger than p(1|0).

[0068] The multi-qubit circuit is described in detail below.

[0069] The multi-qubit circuit includes multiple first qubits. Assuming that the multi-qubit circuit (i.e., n-qubit circuit) includes n first qubits, the multi-qubit circuit is an n-qubit circuit, and its eigenstates may include |q0q1…q n-1 >state, q0q1…q n-1 As a candidate quantum bit string, it can be seen that the number of bits of the candidate quantum bit string is n, and each bit in the candidate quantum bit string corresponds to its own first quantum bit. Therefore, the candidate quantum bit string includes the state of each first quantum bit, that is, the candidate quantum bit string is a state combination of multiple first quantum bits, wherein the i-th bit q in the candidate quantum bit string is i Corresponding to the i-th first quantum bit, each first quantum bit can correspond to a single quantum bit circuit. From the description of the single quantum bit circuit, it can be seen that the eigenstates of the i-th first quantum bit include the |0> state and the |1> state, so q i It can be 0 or 1, i∈{0,1,…,n-1}, and an n-qubit circuit can represent 2 n candidate qubit strings, the wave function of the n-qubit circuit can be expressed as formula (2): |ψ>=α 00 …0|00…0>+α 00 …1|00…1>+…+α 11 …1|11…1> (2)

[0070] Among them, |ψ> is the quantum state of the n first quantum bits, α 00 ...0 to α 11 ...1 are all complex numbers and satisfy the normalization condition: |α 00 …0| 2 +|α 00 …1| 2 +…|α 11 …1| 2 =1, in α 00 ...0 to α 11 ...1 in, for |q0q1…q n-1 >Amplitude of the state;

[0071] When an n-qubit circuit is in a superposition state of multiple eigenstates, the superposition state collapses to 2 n One of the eigenstates, that is, the |ψ> state can collapse to one of the eigenstates from the |00…0> state to the |11…1> state, and the state measurement result can be determined by the wave function as |q0q1…q n-1 The probability of the state is

[0072] Based on this, in a quantum bit circuit including a plurality of first quantum bits, it can be determined that 2 n candidate qubit strings, where n is the number of first qubits in the qubit circuit. Before starting the state measurement, the count value of each candidate qubit string can be set to zero. Then, in the test experiment, the qubit circuit is measured multiple times. In one state measurement, when the state measurement result is |q0q1…q n-1 > state, the candidate quantum bit string q0q1…q n-1 The count value is added by one. After multiple state measurements, the ratio between the count value of each candidate quantum bit string and the total number of measurements can be calculated respectively to obtain the first measurement probability corresponding to each candidate quantum bit string. Therefore, the first measurement probability corresponding to each candidate quantum bit string can be obtained through the test experiment.

[0073] Then, according to the first measurement probability corresponding to the candidate quantum bit string, the candidate quantum bit strings are screened, and the candidate quantum bit strings corresponding to the first measurement probability that meet the deletion conditions are determined as invalid candidate quantum bit strings (i.e., part of the candidate quantum bit strings). For example, when the first measurement probability is zero, the candidate quantum bit string corresponding to the first measurement probability is determined as an invalid candidate quantum bit string, and then by deleting the invalid candidate quantum bit string, the invalid candidate quantum bit string will not contribute to the final ideal result, and the remaining candidate quantum bit strings are determined as target quantum bit strings. It can be considered that the target quantum bit string is a quantum bit string that contributes to the measurement result. By retaining the target quantum bit string, the target quantum bit string can contribute to the final ideal result. Therefore, the number of target quantum bit strings is less than or equal to the number of candidate quantum bit strings. Since there are usually invalid candidate quantum bit strings, after deleting the invalid candidate quantum bit strings, the number of target quantum bit strings is less than the number of candidate quantum bit strings, which can reasonably and effectively reduce the quantum bit error correction space and reduce the resource consumption of correction, thereby effectively improving the efficiency of state measurement.

[0074] Step 202: Create multiple first initial quantum bit strings based on multiple target quantum bit strings, and obtain a first correction matrix obtained by error survey based on the multiple first initial quantum bit strings.

[0075] Among them, since the target quantum bit string is a quantum bit string that contributes to the measurement result, it can be inferred that the first quantum bit corresponding to the target quantum bit string contains a valid quantum bit that contributes to the final ideal result. Therefore, a first initial quantum bit string can be created based on the valid quantum bit. Similar to the target quantum bit string, the first initial quantum bit string is also a quantum bit string that contributes to the measurement result. Each bit in the first initial quantum bit string corresponds to its own valid quantum bit, and the first initial quantum bit string includes the state of each valid quantum bit.

[0076] After creating the first initial qubit string, a quantum calibration circuit is configured in the qubit circuit to measure the operating results of the first initial qubit string. Each first initial qubit string corresponds to a quantum calibration circuit. In an error correction experiment, error correction is performed based on multiple first initial qubit strings. For example, the state of the qubit circuit under each quantum calibration circuit is measured separately. The number of quantum calibration circuits is equal to the number of first initial qubit strings. A quantum calibration circuit refers to a quantum circuit that operates on the corresponding qubit. The quantum calibration circuit can be configured with quantum logic gates that act on the corresponding qubit. In the fields of quantum computing and quantum communication, a quantum calibration circuit is a quantum circuit used to control and calibrate qubit operations.

[0077] In the error correction experiment, multiple state measurements are performed on the qubit circuits under various quantum calibration circuits. The more state measurements are performed, the more accurate the error correction result is. As can be seen from the above description of the measurement results of a single qubit, when performing state measurements on a qubit circuit containing multiple valid qubits, each state measurement result can be one of the initial states. Therefore, the probability distribution of each initial state can be obtained through multiple state measurements. After performing multiple state measurements on the qubit circuit under any quantum calibration circuit, the measurement probability of the state measurement result being each initial state can be determined, that is, the error correction result of the quantum calibration circuit is obtained. Since each quantum calibration circuit corresponds to one of the first initial qubit strings, each quantum calibration circuit corresponds to one of the initial states. It can be seen that for any standard circuit, the initial state corresponding to the quantum calibration circuit can be used as the target initial state, and the remaining initial states can be used as misread initial states. The error correction result of the quantum calibration circuit includes the probability that the state measurement result is the target initial state when the actual state is the target initial state, and the probability that the state measurement result is each misread initial state when the actual state is the target initial state.

[0078] For example, assuming that the number of the first initial quantum bit strings is m, the number of quantum calibration circuits is m. The quantum calibration circuit refers to a quantum circuit that operates on the corresponding quantum bits. The quantum calibration circuit can be configured with quantum logic gates that act on the corresponding quantum bits.

[0079] Among them, before measurement, each quantum calibration circuit needs to initialize each effective quantum bit first. For example, each effective quantum bit is initialized to the |0> state. Then, the corresponding initial state is established by controlling the quantum logic gate in the quantum calibration circuit, that is, the initial state is established according to each first initial quantum bit string. Therefore, the state of each effective quantum bit indicated by the initial state is the same as the state of the quantum bit included in the corresponding first initial quantum bit string. For example, assuming that the first initial quantum bit string is 010, the corresponding initial state is |010>, and the states of the first and third effective quantum bits indicated by this initial state are both |0> states, and the state of the second effective quantum bit is |1> state. Specifically, the effective quantum bits need to be processed through quantum logic gates. For example, by setting an X gate, the second effective quantum bit is flipped from the |0> state to the |1> state. The reason is as follows: the X gate is [0,1;1,0], the |0> state is [1;0], and since [0,1;1,0]·[1;0]=[0;1], the result [0;1] is the |1> state.

[0080] It can be seen that the state measurement results of each quantum calibration circuit will include the measurement results of each effective quantum bit. In the measurement results of any effective quantum bit, due to the existence of factors such as noise and interference, the measurement result of a single quantum bit may be inconsistent with the actual state. For example, the actual state of the effective quantum bit is the |0> state, but the measurement result indicates that the effective quantum bit is in the |1> state. For another example, the actual state of the effective quantum bit is the |1> state, but the measurement result indicates that the effective quantum bit is in the |0> state.

[0081] Based on this, in error correction experiments, it is usually necessary to perform multiple state measurements on the quantum bit circuits under various quantum calibration circuits. The more state measurements are performed, the more accurate the error correction results are. As can be seen from the above description of the measurement results of a single quantum bit, when performing state measurements on a quantum bit circuit containing multiple valid quantum bits, each state measurement result can be one of the initial states. Therefore, the probability distribution of each initial state can be obtained through multiple state measurements. After performing multiple state measurements on the quantum bit circuit under any quantum calibration circuit, the measurement probability of the state measurement result being each initial state can be determined, that is, the error correction result of the quantum calibration circuit is obtained. Since each quantum calibration circuit corresponds to one of the first initial quantum bit strings, each quantum calibration circuit corresponds to one of the initial states. It can be seen that for any standard circuit, the initial state corresponding to the quantum calibration circuit can be used as the target initial state, and the remaining initial states can be used as misread initial states. The error correction result of the quantum calibration circuit includes the probability that the state measurement result is the target initial state when the actual state is the target initial state, and the probability that the state measurement result is each misread initial state when the actual state is the target initial state.

[0082] Therefore, within an acceptable time scale, the read error of each qubit in the same qubit circuit, that is, the flip probability of each qubit being read as the |0> state or the |1> state, can be recorded using a probability matrix. It can be seen that the probability matrix includes the probability that any first initial qubit string is incorrectly measured as another first initial qubit string, and the probability matrix also includes the probability that any first initial qubit string is correctly measured. The inverse matrix of the probability matrix can then be used as a first correction matrix to implement a first correction matrix obtained by error detection based on multiple first initial qubit strings. The first correction matrix is ​​subsequently used to correct the state measurement results of the qubits, which can improve the accuracy of the state measurement results. In addition, when creating multiple first initial qubit strings based on multiple target qubit strings, the number of first initial qubit strings created based on candidate qubit strings can be reduced, thereby reducing the dimension of the first correction matrix when obtaining the first correction matrix obtained by error detection based on multiple first initial qubit strings. Therefore, by deleting invalid candidate qubit strings and creating multiple first initial qubit strings based on multiple target qubit strings, the qubit error correction space can be reasonably and effectively reduced, the resource consumption of correction can be reduced, and the efficiency of state measurement can be effectively improved.

[0083] For example, assuming that the initial states include the |00> state, the |01> state, the |10> state, and the |11> state, the quantum bit circuit under the quantum calibration circuit with the initial state being the |00> state is measured multiple times. For example, the measurement is performed 10,000 times, the state measurement result is the |00> state 9,560 times, the state measurement result is the |01> state 210 times, the state measurement result is the |10> state 228 times, and the state measurement result is the |11> state 2 times. It can be determined that the probability that the first initial quantum bit string 00 is correctly measured is 0.956, and the probability that the first initial quantum bit string 00 is correctly measured is 0.956. The probability that an initial quantum bit string 00 is mistakenly measured as 01 is 0.21, the probability that the first initial quantum bit string 00 is mistakenly measured as 10 is 0.228, and the probability that the first initial quantum bit string 00 is mistakenly measured as 11 is 0.002. Then, the column vectors can be constructed by the error survey results of each quantum calibration circuit respectively. The obtained column vectors are [0.956; 0.21; 0.228; 0.002]. Then, a probability matrix is ​​constructed according to the column vectors corresponding to each quantum calibration circuit, and the inverse matrix of the probability matrix is ​​used as the first correction matrix.

[0084] Step 203: Obtain the probability to be corrected corresponding to each target quantum bit string, wherein the probability to be corrected is a measurement probability obtained by performing multiple state measurements on the quantum bit circuit again.

[0085] Among them, in each subsequent target experiment, the quantum bit circuit can be remeasured and reread to obtain the probability to be corrected corresponding to each target quantum bit string; each target experiment requires multiple state measurements of the quantum bit circuit. The more measurements are made, the more accurate the probability to be corrected is. The probability to be corrected corresponding to any target quantum bit string refers to the measurement probability of the target quantum bit string in all measurement results. The probability to be corrected corresponding to each target quantum bit string can form a first probability distribution. Due to the existence of factors such as noise and interference, it can be considered that the first probability distribution is affected by noise, that is, the probability to be corrected is an error result. The first probability distribution can be corrected according to the first correction matrix to obtain a more accurate probability distribution.

[0086] Step 204: Correct the multiple probabilities to be corrected respectively according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string.

[0087] Among them, since the first correction matrix can be the inverse matrix of the probability matrix, under the inverse action of the inverse matrix, that is, under the action of the first correction matrix, the probability to be corrected as the error result can be corrected to obtain the target probability as the ideal result. This is equivalent to applying the first correction matrix to the result with error after determining the first correction matrix to obtain the result of error elimination.

[0088] Based on this, by obtaining the first measurement probability corresponding to each candidate quantum bit string, some candidate quantum bit strings are deleted according to the first measurement probability, and the remaining candidate quantum bit strings are determined as target quantum bit strings. At this time, relative to the deleted candidate quantum bit strings, the target quantum bit string is the quantum bit string that contributes to the measurement result. Accordingly, when creating multiple first initial quantum bit strings based on multiple target quantum bit strings, the number of first initial quantum bit strings created based on candidate quantum bit strings can be reduced, so that when obtaining the first correction matrix obtained by error survey based on multiple first initial quantum bit strings, the dimension of the first correction matrix is ​​reduced. Therefore, the probability to be corrected corresponding to each target quantum bit string is subsequently obtained, and the multiple probabilities to be corrected are corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string, so that subsequent processing is performed based on the first correction matrix with reduced dimension, which can reduce the resource consumption of correction under the premise of correcting the state measurement result of the quantum bit, and effectively improve the efficiency of state measurement.

[0089] In one possible implementation, after obtaining the target probability, we can further calculate the expected value corresponding to the physical, chemical, biological, and financial quantities. The calculation formula for the expected value Q is: Among them, O i is the i-th observable quantity, P i is the target probability of the i-th observable, N is the number of quantum bits, and under the condition that the number of quantum bit states of the target quantum bit string is N, the probability distribution after eliminating the read error is composed of each P i For example, assuming the first quantum bit string is 000, P1 can be written as P 000 , the observable quantity satisfies: Assume n = 3, then {0,1} 3 It means {000,001,010,011,100,101,110,111}. Due to the reading error, the expected value calculation formula is actually: The probability distribution of a qubit string with read errors is given by the P i ’ is determined, Q is the ideal expected value, and Q’ is the actual expected value.

[0090] 4 and 5 , FIG4 is a columnar schematic diagram of the distribution of the reading results of the quantum bits provided in an embodiment of the present application, and FIG5 is another columnar schematic diagram of the distribution of the reading results of the quantum bits provided in an embodiment of the present application.

[0091] Among them, Figure 4 shows the probability that a quantum bit in the |0> state is mistakenly measured as the |1> state, and Figure 5 shows the probability that a quantum bit in the |1> state is mistakenly measured as the |0> state. In each control group, the bar on the left is used to indicate the probability of the ideal result, and the bar on the right is used to indicate the probability of the direct measurement result. It can be seen that the reading error of the quantum bit can be regarded as a disturbance to the ideal result. Although the reading result of each quantum bit has deviated from the ideal result, the overall distribution trend of different quantum bit strings is maintained, so the ideal distribution P of the quantum bit string can be made. i Contained in the experimental distribution P carrying read errors i ′, that is, satisfying formula (3):

[0092] Therefore, this is an assumption that satisfies the effectiveness of quantum computing hardware. Although the quantum computing results are biased due to noise interference, they are not completely wrong. In addition, as the scale of quantum bits increases, the global quantum computing space corresponding to the quantum bits increases exponentially. If only the quantum bits involved in the experimental distribution that carry read errors are considered, the time and space scales required for calculation of read error processing and elimination can be effectively reduced.

[0093] In one possible implementation, the "creating multiple first initial quantum bit strings based on multiple target quantum bit strings" in step 202 can be achieved in the following way: when the state of any first quantum bit in each target quantum bit string is the first state, deleting the first quantum bit from the multiple first quantum bits, and determining the remaining first quantum bits as second quantum bits; creating multiple first initial quantum bit strings based on the second quantum bits.

[0094] The number of quantum bit states included in the target quantum bit string is greater than or equal to the number of quantum bit states included in the first initial quantum bit string.

[0095] Among them, since the target quantum bit string is a quantum bit string that contributes to the measurement result, it is inferred that the first quantum bit corresponding to the target quantum bit string contains a valid quantum bit that contributes to the final ideal result. Therefore, the first initial quantum bit string can be created based on the valid quantum bit (that is, the second quantum bit).

[0096] For example, before obtaining the first measurement probability corresponding to each candidate quantum bit string, it is necessary to initialize each first quantum bit first. Assuming that each first quantum bit is initialized to the |0> state, the initialization state of the first quantum bit can be used as the first state, that is, the first state is the |0> state. The target quantum bit string and the candidate quantum bit string have the same number of first quantum bits. Whether the corresponding first quantum bit contributes is determined based on the state of the first quantum bit in the target quantum bit string.

[0097] Based on this, when the state of the first quantum bit in each target quantum bit string is the first state, that is, the state of the first quantum bit has not changed in multiple state measurements, it can be inferred that the state of the first quantum bit does not contribute to the final ideal result, that is, the first quantum bit whose state has not changed in multiple state measurements is an invalid quantum bit. Therefore, the first quantum bit whose state has not changed in multiple state measurements is deleted, and the remaining first quantum bits are determined as second quantum bits. The state of the second quantum bit may contribute to the final ideal result, that is, the second quantum bit is an "important quantum bit" (or a valid quantum bit). Then, a global error survey is performed on the second quantum bit. Global error survey refers to taking the state combination of all second quantum bits as the initial state, and then performing error survey on each initial state separately. Subsequently, a correction matrix corresponding to all second quantum bits can be determined, and the numerical value of the state combination of each second quantum bit indicated by the initial state can be used as the first initial quantum bit string. Therefore, the first initial quantum bit string can be created based on the second quantum bit. The first initial quantum bit string is a quantum bit string that contributes to the measurement result.

[0098] Assume that the number of the first qubit is N and the number of the second qubit is N P , N P When global error survey is performed on the first qubit, since the measurement results of each first qubit include the |0> state and the |1> state, the number of initial states corresponding to the first qubit is 2. N When performing global error survey on the second qubit, since the measurement results of each second qubit include the |0> state and the |1> state, the number of initial states corresponding to the second qubit is That is, the number of the first initial bit string is N P Usually less than N, that is Less than 2 N Therefore, compared with the scenario of global error detection for the first quantum bit, the number of initial states is significantly reduced in the scenario of global error detection for the second quantum bit, which can reasonably and effectively reduce the quantum bit error correction space, which is equivalent to the resource consumption of error correction being reduced by 2 NReduce to Under the premise of correcting the state measurement results of quantum bits, the resource consumption of correction is reduced, and the efficiency of state measurement is effectively improved.

[0099] For example, in a three-qubit circuit, assuming that multiple target qubit strings include target qubit string 000, target qubit string 001, target qubit string 010, and target qubit string 011, each target qubit string corresponds to three first qubits. It can be seen that the state of the first first qubit in the three target qubit strings is |0> state, which means that the state of the first first qubit has not changed in multiple state measurements, and the state of the first first qubit has no contribution to the final ideal result. Therefore, the first first qubit needs to be deleted, and the second first qubit and the third first qubit need to be deleted. If the states of the sub-bits in the three target quantum bit strings are not all in the |0> state, it means that the states of the second first quantum bit and the third first quantum bit have changed during multiple state measurements, and the states of the second first quantum bit and the third first quantum bit may contribute to the final ideal result. Therefore, the second first quantum bit and the third first quantum bit need to be used as second quantum bits to obtain two second quantum bits. Then, a first initial quantum bit string is created based on the two second quantum bits. The multiple first initial quantum bit strings can include quantum bit string 00, quantum bit string 01, quantum bit string 10 and quantum bit string 11.

[0100] The following describes in detail two methods for obtaining the probability to be corrected. In addition to the following two methods, the probability to be corrected can also be obtained by other methods, which are not limited in the embodiments of the present application.

[0101] In some embodiments, the "obtaining the probability of correction corresponding to each target qubit string" in step 203 can be achieved by controlling the qubit circuit to shield the deleted first qubit and then obtaining the probability of correction corresponding to each target qubit string;

[0102] Among them, the probability to be corrected is the measurement probability obtained by performing multiple state measurements on the quantum bit circuit again after shielding the deleted first quantum bit in the quantum bit circuit, that is, only the state of the second quantum bit is measured in the quantum bit circuit, but the state of the deleted first quantum bit is not measured.

[0103] Based on this, in a state measurement of the current experiment (such as a test experiment or an error correction experiment), the state measurement result is determined by the measurement results of each second quantum bit. Therefore, in multiple state measurements of the current experiment, the probability of correction corresponding to each target quantum bit string can be determined according to each state measurement result. Since the number of target quantum bit strings is smaller than the number of candidate quantum bit strings, the quantum bit error correction space can be reasonably and effectively reduced, the resource consumption of correction can be reduced, and the efficiency of state measurement can be effectively improved. In addition, since there is no need to measure the states of all first quantum bits, the efficiency of state measurement is effectively improved.

[0104] For example, assuming that the number of first qubits is four and the first first qubit needs to be deleted, the number of second qubits is three. It can be considered that the deleted first qubit is in the first state, that is, the first first qubit is in the |0> state. After one state measurement, the state of the first second qubit is measured to be the |0> state, that is, the second first qubit is in the |0> state, and the state of the second second qubit is measured to be the |1> state, that is, the third first qubit is in the |1> state, and the state of the third second qubit is measured to be the |1> state, that is, the fourth first qubit is in the |1> state. Therefore, the current state measurement result of the qubit circuit is the |0011> state, and the target qubit string corresponding to the |0011> state is 0011. Therefore, the count value of the target qubit string 0011 is increased by one. After multiple state measurements, the ratio between the count value of each target qubit string and the total number of measurements can be calculated respectively to obtain the measurement probability corresponding to each target qubit string (that is, the probability to be corrected).

[0105] In some embodiments, "obtaining the probability to be corrected corresponding to each target quantum bit string" in step 203 can be achieved by: obtaining the second measurement probability corresponding to each candidate quantum bit string; and using the second measurement probability corresponding to the target quantum bit string as the probability to be corrected.

[0106] Among them, the second measurement probability is obtained by performing multiple state measurements on the quantum bit circuit again, for example, measuring the states of all first quantum bits in the quantum bit circuit, determining the second measurement probability corresponding to each candidate quantum bit string, and then determining the probability to be corrected corresponding to the target quantum bit string.

[0107] Based on this, in a state measurement of the current experiment, the state measurement result is determined by the measurement results of each first quantum bit. Similar to the test experiment, in multiple state measurements of the current experiment, the second measurement probability corresponding to each candidate quantum bit string can be determined according to each state measurement result. Since the candidate quantum bit string includes the target quantum bit string, the probability to be corrected corresponding to the target quantum bit string can be determined in the second measurement probability corresponding to each candidate quantum bit string. Since the number of target quantum bit strings is smaller than the number of candidate quantum bit strings, the quantum bit error correction space can be reasonably and effectively reduced, the resource consumption of correction can be reduced, and the efficiency of state measurement can be effectively improved.

[0108] In some embodiments, after deleting invalid candidate quantum bit strings according to the first measurement probability, the correction matrix can be reduced by deleting the invalid candidate quantum bit strings. The correction matrix can then be used to correct the probability to be corrected to obtain the target probability. The greater the target number of invalid candidate quantum bit strings, the greater the reduction amplitude of the correction matrix. When the correction matrix is ​​in a reasonable reduced state, it can meet the assumption that the reading of quantum bits is independent of each other, that is, it meets the assumption that the noise of quantum bits is also independent of each other, including the following two scenarios.

[0109] In the first scenario, "creating multiple first initial qubit strings based on multiple target qubit strings" in step 202 can be achieved by obtaining a target number of candidate qubit strings; when the target number is greater than a first threshold, creating multiple first initial qubit strings based on the multiple target qubit strings. The first threshold can be a value determined based on actual business needs and can be freely adjusted. It can also be an empirical value set by technicians based on historical data and statistical analysis results. This embodiment of the present application is not limited to the method for obtaining the first threshold.

[0110] Then, a first correction matrix is ​​obtained based on error survey of multiple first initial quantum bit strings; the probability to be corrected corresponding to each target quantum bit string is obtained, wherein the probability to be corrected is the measurement probability obtained by performing multiple state measurements on the quantum bit circuit again; the multiple probabilities to be corrected are corrected respectively according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string.

[0111] Based on this, in the first scenario, after obtaining the target number of some candidate quantum bit strings, the size relationship between the target number and the first number threshold is judged. When the target number is greater than the first number threshold, it can be considered that the reduction amplitude is too large, that is, it is in an unreasonable reduction situation, and cannot meet the assumption that the noise of the quantum bits is also independent of each other. It is necessary to consider the situation where the quantum bits will crosstalk with each other when reading, and it is necessary to perform global error survey on the second quantum bit, and create multiple first initial quantum bit strings based on multiple target quantum bit strings.

[0112] The first quantity threshold is determined by the number of second quantum bits. Assuming that the number of second quantum bits is N, the first quantity threshold is 2 N / 2 , when the number of targets is greater than 2 N / 2 When , it is in an unreasonable reduction situation, and the first scenario needs to be used to determine the target probability.

[0113] The second scenario: when the target number is less than or equal to the first number threshold, a second correction matrix corresponding to each second quantum bit is obtained, wherein the second correction matrix is ​​obtained based on error survey of multiple second initial quantum bit strings, and the second initial quantum bit string includes the state of a single second quantum bit; the direct product of the multiple second correction matrices is determined as a third correction matrix, and the multiple probabilities to be corrected are corrected according to the third correction matrix to obtain the target probability corresponding to each target quantum bit string.

[0114] Based on this, in the second scenario, after obtaining the target number of invalid candidate quantum bit strings, the size relationship between the target number and the first number threshold is judged. When the target number is less than or equal to the first number threshold, it can be considered to be in a reasonable reduction situation, which can meet the assumption that the noise of the quantum bits is also independent of each other, and the second quantum bit can be locally error surveyed. Local error survey refers to taking the state of each second quantum bit as the initial state, and then performing error survey on each initial state separately, so that the correction matrix corresponding to each second quantum bit can be determined separately.

[0115] For example, the numerical value of the state of the second quantum bit indicated by the initial state is used as the second initial quantum bit string. Therefore, the second initial quantum bit string may include the state of a single second quantum bit. Since the measurement result of each first quantum bit includes the |0> state and the |1> state, the second initial quantum bit string corresponding to each second quantum bit includes 0 and 1. For any second quantum bit, error survey is performed based on the second initial quantum bit string 0 and the second initial quantum bit string 1 corresponding to the second quantum bit to obtain the probability matrix corresponding to the second quantum bit, and the inverse matrix of the probability matrix is ​​used as the second correction matrix corresponding to the second quantum bit; after determining the second correction matrices corresponding to all second quantum bits, the direct product of all second correction matrices is calculated to obtain the third correction matrix. The direct product refers to the tensor product. By calculating the direct product of all second correction matrices, the quantum entanglement between each second quantum bit can be described.

[0116] It can be seen that the time complexity of calculating the inverse matrix of the probability matrix is ​​O(n 3 ), n refers to the matrix dimension of the probability matrix. Therefore, assuming that the number of second qubits is N, when determining the first correction matrix in the first scenario, the time complexity of calculating the inverse matrix is ​​O(N 3 ), when the number of targets is less than or equal to 2 N / 2 When the target probability is determined in the second scenario, the time complexity of calculating the inverse matrix is ​​reduced to O(2 3 ), it can be seen that when the target probability is determined by the second scenario, the time consumption of the error elimination process can be greatly reduced, that is, the error elimination resource consumption of calculating the inverse matrix can be greatly reduced.

[0117] For example, referring to Figure 6, Figure 6 is a bar graph of the error rate provided by an embodiment of the present application. As can be seen from Figure 6, when the error is directly measured without error elimination, the error rate is relatively large; in local error survey, the corresponding second correction matrix can be determined by the state of a single second quantum bit. When the number of initial states is two, that is, the number of calibration circuits is two, each second quantum bit shares these two calibration circuits for state measurement. Assuming that each calibration circuit is T times and there are n second quantum bits, each second quantum bit is measured 2T / n times on average, and the error rate is effectively reduced; when the number of initial states is 2n, that is, the number of calibration circuits is 2n, the state of each second quantum bit is measured using the corresponding calibration circuit. Assuming that each calibration circuit is T times, each second quantum bit is measured 2T times on average, and the error rate is also effectively reduced; in global error survey, the error rate is effectively reduced.

[0118] In some embodiments, when the target number is less than or equal to a first number threshold, obtaining a second correction matrix corresponding to each second qubit can be achieved by: when the target number is less than or equal to the first number threshold and the target number is greater than or equal to a second number threshold, obtaining a second correction matrix corresponding to each second qubit; and / or, when the target number is less than or equal to a third number threshold, obtaining a second correction matrix corresponding to each second qubit; wherein the second number threshold is less than the first number threshold, and the third number threshold is less than the second number threshold. The second number threshold and the third number threshold can each be a value determined according to actual business needs and can be freely adjusted; the second number threshold and the third number threshold can each be an empirical value set by a technician based on historical data and statistical analysis results. The embodiments of the present application are not limited to the method for obtaining the second number threshold and the third number threshold.

[0119] Based on this, in the second scenario, when the number of targets is less than or equal to the first number threshold, it can be considered to be in a reasonable reduction situation. It is also necessary to further select a specific method based on the measurement accuracy distance between the first scenario and the second scenario. Under different target numbers, the target probability can be determined using the first scenario and the second scenario respectively. Then, a sufficient number of tests can be conducted to determine the measurement accuracy of the first scenario and the measurement accuracy of the second scenario, and then the measurement accuracy distance between the first scenario and the second scenario can be calculated.

[0120] For example, it can be determined that when the number of targets is less than or equal to the first number threshold and the number of targets is greater than or equal to the second number threshold, the measurement accuracy distance between the first scenario and the second scenario is small. It can also be determined that when the number of targets is less than or equal to the third number threshold, the measurement accuracy distance between the first scenario and the second scenario is small. In order to reduce the time consumption of the error elimination process, when the measurement accuracy distance between the first scenario and the second scenario is small, the second scenario is preferentially selected to determine the target probability.

[0121] For example, referring to FIG7 and FIG8, FIG7 is a curve diagram of the measurement accuracy provided by an embodiment of the present application, and FIG8 is another curve diagram of the measurement accuracy provided by an embodiment of the present application, wherein the quantum bit circuit includes 10 first quantum bits, and can calculate the first number threshold of 2 5=32. When the number of targets is less than or equal to 32, it is in a reasonable reduction situation. Figure 7 shows the measurement accuracy distance when the number of targets is in the range of 0 to 32, and Figure 8 shows the measurement accuracy distance when the number of targets is in the range of 900 to 1024. The vertical axis is the difference between the measurement accuracy of the second scenario and the measurement accuracy of the first scenario. It can be seen that in the reasonable reduction situation, the measurement accuracy of the second scenario is accurate at both ends, that is, it includes two reasonable intervals.

[0122] Based on this, when the target number is within a reasonable range, the measurement accuracy of the second scenario is greater. Therefore, it is necessary to set a second number threshold and a third number threshold. When the target number is less than or equal to the first number threshold, and when the target number is greater than or equal to the second number threshold, the target number is within a larger reasonable range. When the target number is less than or equal to the third number threshold, the target number is within a smaller reasonable range.

[0123] When the number of targets is less than the second number threshold and greater than the third number threshold, the measurement accuracy of the second scenario is significantly lower than that of the first scenario. In order to ensure measurement accuracy, the first scenario is preferably used to determine the target probability.

[0124] In addition, when the number of targets is greater than the first threshold, it can be considered that it is in an unreasonable reduction situation, and the assumption that the noise of quantum bits is also independent of each other cannot be met. It is necessary to consider the situation where quantum bits will crosstalk with each other when reading. It is necessary to choose the first scenario to determine the target probability, that is, to satisfy the following formula (4):

[0125] Among them, A P_bs1,bs2 represents the probability that the target qubit string bs1 is incorrectly measured as the target qubit string bs2, N represents the number of first qubits in the target qubit string bs1, and the number of first qubits in the target qubit string bs1 and the target qubit string bs2 are equal. represents the probability that the N-1-kth first qubit in the target qubit string bs1 is mistakenly measured as the N-1-kth first qubit in the target qubit string bs2. By multiplying the probabilities of each first qubit in the target qubit string bs1 being mistakenly measured, we get Since the qubits will crosstalk with each other when reading, A P_bs1,bs2 and Not equal.

[0126] In some embodiments, there are multiple quantum bit circuits, and each quantum bit circuit corresponds to its own first correction matrix. The probability to be corrected is obtained by performing multiple state measurements on one of the target quantum bit circuits in the multiple quantum bit circuits again. The second quantum bit in the target quantum bit circuit is the quantum bit corresponding to the target virtual quantum bit after quantum circuit compilation. The multiple probabilities to be corrected are corrected according to the first correction matrix. Before obtaining the target probability corresponding to each target quantum bit string, the state measurement method also includes: obtaining mapping information corresponding to the target quantum bit circuit, wherein the mapping information is used to indicate the bit identifier mapping relationship between the second quantum bit and the target virtual quantum bit; obtaining the first bit identifier of each target virtual quantum bit, obtaining the second bit identifier of the second quantum bit according to the first bit identifier and the mapping information, and obtaining the corresponding first correction matrix according to the identifier string composed of multiple second bit identifiers.

[0127] The qubit (also called a physical qubit, such as the first qubit or the second qubit) in a qubit circuit refers to the unit used to store and manipulate quantum information in an actual physical system. The qubit in a qubit circuit is the fundamental component of quantum computer hardware. It is implemented by a specific physical system and directly corresponds to the physical entities in quantum computing hardware, such as ion traps and superconducting circuits. However, it is subject to real-world physical constraints, such as noise and decoherence. The qubit in a qubit circuit exhibits fundamental properties of quantum mechanics, such as superposition and entanglement. Virtual qubits (such as target virtual qubits and initial virtual qubits) are theoretical concepts used to represent quantum information in quantum algorithms and quantum circuit design. They do not directly correspond to actual qubits in physical hardware, but rather serve as abstract mathematical objects used to describe quantum states and quantum operations. The characteristics of virtual qubits include their ability to construct and represent quantum circuits and logic gates at the algorithmic level. In short, the qubit in a qubit circuit is the actual unit in quantum computer hardware, while the virtual qubit is a concept used at the abstract level of quantum computing to design and analyze quantum algorithms.

[0128] Among them, through quantum circuit compilation, the quantum logic gate operation performed on the target virtual quantum bit can be mapped to the physical gate operation on the real quantum bit hardware. Therefore, in the real quantum bit hardware, there will be quantum circuit compilation, that is, the quantum bit that actually performs the operation on the quantum bit hardware may not correspond one-to-one with the quantum bit expected by the user. During the quantum circuit compilation, the bit identification mapping relationship between the second quantum bit and the target virtual quantum bit can be determined, which is equivalent to determining the corresponding mapping information during the quantum circuit compilation.

[0129] Based on this, in the test experiment, the state of different quantum bit circuits can be measured to determine the second quantum bit as the important quantum bit. Then, in the error correction experiment, the corresponding second quantum bit can be accurately surveyed point-to-point to determine the first correction matrix matched by each quantum bit circuit. Since the mapping information determined when each quantum bit circuit performs quantum circuit compilation is different, in the target experiment of the target quantum bit circuit, it is necessary to obtain the mapping information corresponding to the target quantum bit circuit in the test experiment, and then determine the second bit identifier of the corresponding second quantum bit on the real quantum bit hardware through the first bit identifier and mapping information of the target virtual quantum bit. For example, there are three target virtual quantum bits in total. The mapping information can be used to determine that the second quantum bit corresponding to the first target virtual quantum bit q′0 is q 10 , the second quantum bit corresponding to the second target virtual quantum bit q′1 is q 11 , the second quantum bit corresponding to the third target virtual quantum bit q′2 is q 12 The subscript of the quantum bit is the bit identifier, and then the corresponding first correction matrix can be obtained by matching the identifier string [10,11,12] composed of multiple second bit identifiers. The accurate correction matrix can be obtained, and the corresponding error elimination effect can be applied to the corresponding quantum bit in the subsequent implementation.

[0130] In some embodiments, before obtaining the probability to be corrected corresponding to each target quantum bit string, the state measurement method also includes: constructing a virtual quantum bit space corresponding to the quantum bit hardware, wherein the quantum bit hardware includes multiple quantum bit circuits; obtaining target topology information, and determining multiple initial virtual quantum bits from the virtual quantum bit space based on the target topology information, wherein the target virtual quantum bit is one of the initial virtual quantum bits; obtaining candidate topology information of each quantum bit circuit, and screening out candidate quantum bit circuits whose candidate topology information is the same as the target topology information from multiple quantum bit circuits; obtaining precision information of the candidate quantum bit circuit, and screening out the target quantum bit circuit from the candidate quantum bit circuit based on the precision information; and constructing mapping information between the initial virtual quantum bit and the first quantum bit in the target quantum bit circuit.

[0131] In the field of quantum computing, the topological information corresponding to a qubit circuit (such as target topology information and candidate topology information) can include important information such as the number of qubits and the connectivity between qubits. In quantum computers, the number of qubits, as included in topological information, is a key metric for measuring computing power. More qubits mean the ability to handle more complex computational tasks. The number of qubits in topological information refers to the total number of physical or logical qubits that comprise the quantum computing system. In a quantum computer, the connectivity between qubits determines the topological structure of the quantum computer. This connectivity has a direct impact on the efficiency and power of quantum computing. For example, nearest-neighbor connectivity between qubits indicates that a qubit only interacts with its nearest neighbors. The topological structure between qubits, i.e., the arrangement and connection of qubits, forms different topological structures such as chains, rings, lattices, and more complex structures. Entanglement between qubits allows entangled qubits to interact across distances greater than those of their nearest neighbors, thus enabling long-distance information transmission and processing. Therefore, topological information not only describes the number and connectivity of qubits but also encompasses how qubits are combined and how these combinations influence quantum computing performance.

[0132] Among them, the quantum bit hardware may include multiple real quantum bits, and the virtual quantum bit space may be determined by the virtual quantum bits corresponding to each real quantum bit. Then, the target topology information may be obtained in the target experiment. The target topology information may include the number of quantum bits, and information such as the connectivity between quantum bits. The candidate topology information corresponding to each quantum bit circuit may also include the number of quantum bits, and information such as the connectivity between quantum bits. Therefore, the candidate quantum bit circuit may be screened out based on the candidate topology information and the target topology information. Since the precision information of each quantum bit circuit may be different, the higher the precision indicated by the precision information, the lower the error rate of the quantum bit circuit. Conversely, the lower the precision indicated by the precision information, the higher the error rate of the quantum bit circuit. When screening out the target quantum bit circuit from the candidate quantum bit circuit, the candidate quantum bit circuit with the highest precision may be preferentially selected as the target quantum bit circuit, which can improve the accuracy of quantum computing. Therefore, the mapping information between the initial virtual quantum bit and the first quantum bit in the target quantum bit circuit can be constructed based on the selected target quantum bit circuit.

[0133] In some embodiments, "creating multiple first initial quantum bit strings based on multiple target quantum bit strings" in step 202 can be achieved in the following way: when each first quantum bit exists in the second state in at least one target quantum bit string, each target quantum bit string is determined as a first initial quantum bit string.

[0134] Among them, since the target quantum bit string is a quantum bit string that contributes to the measurement result, it is inferred that the first quantum bit corresponding to the target quantum bit string contains a valid quantum bit that contributes to the final ideal result. Therefore, the first initial quantum bit string can be created based on the valid quantum bit.

[0135] For example, before obtaining the first measurement probability corresponding to each candidate quantum bit string, it is necessary to initialize each first quantum bit first. Assuming that each first quantum bit is initialized to the |0> state, the initialization state of the first quantum bit can be used as the first state, that is, the first state is the |0> state, and the |1> state can be used as the second state. The target quantum bit string and the candidate quantum bit string have the same number of first quantum bits. According to the state of each first quantum bit, it is determined whether the corresponding first quantum bit has contributed.

[0136] Based on this, when each first quantum bit exists in the second state in at least one target quantum bit string, it means that the state of each first quantum bit contributes to the final ideal result. Each target quantum bit string is used as the first initial quantum bit string, that is, the first quantum bit whose state changes in multiple state measurements is a valid quantum bit. Therefore, although the first quantum bit whose state does not change in multiple state measurements is not deleted, since the number of target quantum bit strings is less than the number of candidate quantum bit strings, the quantum bit error correction space can be reasonably and effectively reduced, the resource consumption of correction can be reduced, and the efficiency of state measurement can be effectively improved.

[0137] For example, in a three-qubit circuit, assuming that the target qubit string includes 000 (i.e., the first target qubit string), 001 (i.e., the second target qubit string), 100 (i.e., the third target qubit string) and 110 (i.e., the fourth target qubit string), each target qubit string corresponds to three first qubits. It can be seen that the first first qubit is in the |1> state in the third target qubit string and the fourth target qubit string, the second first qubit is in the |1> state in the fourth target qubit string, and the third first qubit is in the |1> state in the second target qubit string. That is, when the three first qubits are in the |1> state in at least one target qubit string, it means that the states of the three first qubits all contribute to the final ideal result. Therefore, there is no need to delete the first qubit in the target qubit string, and each target qubit string needs to be used as the first initial qubit string.

[0138] In some embodiments, "obtaining a first correction matrix obtained by error survey based on multiple first initial quantum bit strings" in step 203 can be achieved by: obtaining a third measurement probability corresponding to each first initial quantum bit string, wherein the third measurement probability is obtained by performing multiple state measurements on the quantum calibration circuit corresponding to the first initial quantum bit string; determining the third measurement probability corresponding to the same first initial quantum bit string as a column element, and constructing a target matrix based on multiple column elements; and using the inverse matrix of the target matrix as the first correction matrix.

[0139] Among them, in the error correction experiment, it is usually necessary to perform multiple state measurements on the quantum bit circuits under various quantum calibration circuits respectively. From the above description, it can be seen that each first initial quantum bit string corresponds to an initial state. When the quantum bit circuit containing multiple valid quantum bits is measured, each state measurement result can be one of the initial states. Therefore, after multiple state measurements, for any first initial quantum bit string, the third measurement probability corresponding to the first initial quantum bit string includes the probability that the state measurement result is the target initial state when the actual state is the target initial state, that is, it includes the probability that the first initial quantum bit string is correctly measured. The third measurement probability also includes the probability that the state measurement result is each misread initial state when the actual state is the target initial state, that is, it includes the probability that the first initial quantum bit string is incorrectly measured as other first initial quantum bit strings.

[0140] Based on this, the reading error of each quantum bit in the same quantum bit circuit under an acceptable time scale, that is, the flipping probability of each quantum bit being read as the |0> state or the |1> state, can be recorded using a probability matrix. The probability matrix can be used as the target matrix, and the third measurement probability can be used as the column element of the target matrix. The column vector of the target matrix is ​​constructed by the third measurement probability corresponding to the first initial quantum bit string, and the target matrix is ​​constructed by the column vector corresponding to each first initial quantum bit string. It can be seen that the target matrix includes the probability that any first initial quantum bit string is incorrectly measured as other first initial quantum bit strings, and the probability matrix also includes the probability that any first initial quantum bit string is correctly measured. Then, the inverse matrix of the probability matrix can be used as the first correction matrix, realizing the first correction matrix obtained by error survey based on multiple first initial quantum bit strings. The subsequent use of the first correction matrix to correct the state measurement results of the quantum bits can improve the accuracy of the state measurement results.

[0141] For example, assuming that the plurality of first initial quantum bit strings include a first initial quantum bit string 00, a first initial quantum bit string 01, a first initial quantum bit string 10, and a first initial quantum bit string 11, the third measurement probability corresponding to the first initial quantum bit string 00 includes P(00|00), P(01|00), P(10|00), and P(11|00), and the third measurement probability corresponding to the first initial quantum bit string 01 includes P(00|01), P(01|01), P(10|01), and P( The third measurement probability corresponding to the first initial quantum bit string 10 includes P(00|10), P(01|10), P(10|10) and P(11|10). The third measurement probability corresponding to the first initial quantum bit string 11 includes P(00|11), P(01|11), P(10|11) and P(11|11). Taking the third measurement probability corresponding to the first initial quantum bit string 00 as an example, P(00|00) refers to the probability that the first initial quantum bit string 00 is correctly measured. P(01|00) refers to the probability that the first initial quantum bit string 00 is incorrectly measured as the first initial quantum bit string 01, P(10|00) refers to the probability that the first initial quantum bit string 00 is incorrectly measured as the first initial quantum bit string 10, and P(11|00) refers to the probability that the first initial quantum bit string 00 is incorrectly measured as the first initial quantum bit string 11; therefore, through multiple state measurements, each third measurement probability can be determined, and then the target matrix is ​​constructed by the third measurement probabilities corresponding to the four first initial quantum bit strings, wherein the third measurement probability corresponding to the first initial quantum bit string 00 can be used as the first column vector of the target matrix, and the third measurement probability corresponding to the first initial quantum bit string 01 can be used as the second column vector of the target matrix, and the third measurement probability corresponding to the first initial quantum bit string 10 can be used as the third column vector of the target matrix, and the third measurement probability corresponding to the first initial quantum bit string 11 can be used as the fourth column vector of the target matrix, and then the inverse matrix of the target matrix can be used as the first correction matrix.

[0142] In some embodiments, the step 204 of "correcting multiple probabilities to be corrected according to the first correction matrix to obtain target probabilities corresponding to each target quantum bit string" can be achieved by: determining the product of the first correction matrix and the vector to be corrected as the target probability corresponding to each target quantum bit string; and / or, fitting the inverse matrix of the first correction matrix and the vector to be corrected based on the least squares method to obtain the target probability corresponding to each target quantum bit string; wherein the vector to be corrected is constructed from multiple probabilities to be corrected.

[0143] The least squares method (LSM) is a mathematical optimization technique that finds the best-fit line or curve for data by minimizing the sum of squared errors. In statistics, the Least Squares Method is often used in regression analysis, particularly linear regression. The basic idea behind the Least Squares Method is to find a line or curve that minimizes the sum of squared differences between the predicted and observed values ​​for a set of observed data points.

[0144] Based on this, in the error correction experiment, the error detection is first performed based on multiple first initial quantum bit strings to obtain the first correction matrix. Then, in each subsequent target experiment, the quantum bit circuit can be re-measured and re-read to obtain the probability of correction corresponding to each target quantum bit string. The vector to be corrected can be constructed by the probability to be corrected corresponding to each target quantum bit string. The vector to be corrected is a column vector. Let the vector to be corrected be The first correction matrix is Methods for determining target probability include but are not limited to:

[0145] (1) The vector to be corrected is used to represent the experimental probability distribution with errors. The first correction matrix can be applied to the experimental probability distribution with errors to obtain the probability distribution after eliminating the reading error. The target vector can be used to represent the probability distribution after eliminating the reading error. Let the target vector be because Therefore, the calculation formula of the target vector is as follows:

[0146] Among them, the target vector is a column vector, and the target probability corresponding to each target quantum bit string is the column element of the target vector. The target vector can be calculated by this calculation formula

[0147] (2) The inverse matrix of the first correction matrix is ​​A P In the least squares method, for a given model y = f(x, θ), y is the observation data, x is the input, and θ is the parameter to be estimated. The goal of the least squares method is to find the optimal parameter θ so that the sum of squares of the residuals between the observation data and the model's predictions is minimized. Here, the observation data y is the vector to be corrected Input x is the matrix A P , parameter θ is the target vector Assuming that the minimum value of the residual sum of squares between the observed data and the model's predicted values ​​is zero, the fitting formula can be determined as follows:

[0148] Among them, the target vector is a column vector, and the target probability corresponding to each target quantum bit string is the column element of the target vector. The target vector can be calculated by the fitting formula

[0149] For example, assuming that multiple target quantum bit strings are target quantum bit string 000, target quantum bit string 001, and target quantum bit string 010, the probabilities to be corrected corresponding to target quantum bit string 000, target quantum bit string 001, and target quantum bit string 010 are obtained respectively, and the probability to be corrected corresponding to target quantum bit string 000 is set to p′ 000 , the probability of correction corresponding to the target quantum bit string 001 is p′ 001 , the probability of correction corresponding to the target quantum bit string 010 is p′ 010 , the vector to be corrected can be determined as Since the state of the first first qubit in each target qubit string is all |0> state, that is, all are first state, the above processing method needs to delete the first first qubit, determine the remaining first qubit as the second qubit, and then create multiple first initial qubit strings based on the second qubit. The multiple first initial qubit strings include the first initial qubit string 00, the first initial qubit string 01, the first initial qubit string 10 and the first initial qubit string 11. Then, based on the multiple first initial qubit strings, error survey is performed to obtain a first correction matrix with four rows and four columns. Using the calculation formula The specific calculation methods include but are not limited to:

[0150] (1) Since the first initial quantum bit string 11 corresponds to the candidate quantum bit string 011, but the candidate quantum bit string 011 has not been measured, it can be considered that the probability of correction corresponding to the candidate quantum bit string 011 is zero, that is, the probability corresponding to the candidate quantum bit string 011 is p′ 011 = 0, update the vector to be corrected to This is equivalent to performing a zero-filling operation in the corresponding position of the vector to be corrected, so that the first correction matrix can be multiplied by the vector to be corrected, and then the first correction matrix is ​​calculated. and the vector to be corrected The product of , we get the target vector Then p 000 As the target probability corresponding to the target quantum bit string 000, p 001 As the target probability corresponding to the target quantum bit string 001, p 010 As the target probability corresponding to the target quantum bit string 010.

[0151] (2) Since the first initial quantum bit string 11 corresponds to the candidate quantum bit string 011, but the candidate quantum bit string 011 has not been state measured, the first correction matrix with four rows and four columns can be Delete the fourth row and the fourth column in the first correction matrix Update to a matrix of three rows and three columns, and then calculate the first correction matrix and the vector to be corrected Multiply by to get the target vector Then p 000 As the target probability corresponding to the target quantum bit string 000, p 001 As the target probability corresponding to the target quantum bit string 001, p 010 As the target probability corresponding to the target quantum bit string 010.

[0152] In some embodiments, "deleting some candidate quantum bit strings from multiple candidate quantum bit strings based on the first measurement probability" in step 201 can be achieved by: deleting the candidate quantum bit strings whose first measurement probability is a preset probability from multiple candidate quantum bit strings; and / or, deleting the candidate quantum bit strings whose first measurement probability is less than or equal to the probability threshold from multiple candidate quantum bit strings.

[0153] Among them, the probability threshold can be a value determined according to actual business needs and can be adjusted freely; the probability threshold can also be an empirical value set by technicians based on historical data and statistical analysis results. The embodiments of this application are not limited to the method of obtaining the probability threshold.

[0154] Among them, according to the first measurement probability corresponding to the candidate quantum bit string, the candidate quantum bit strings are screened, and the candidate quantum bit strings corresponding to the first measurement probability that meet the deletion condition are regarded as invalid candidate quantum bit strings (that is, some candidate quantum bit strings that need to be deleted). The deletion condition can be that the first measurement probability is equal to the preset probability, for example, the preset probability can be zero, and the deletion condition can also be that the first measurement probability is less than or equal to the probability threshold. Then, by deleting the invalid candidate quantum bit strings, the invalid candidate quantum bit strings will not contribute to the final ideal result, and the remaining candidate quantum bit strings are determined as target quantum bit strings. It can be considered that the target quantum bit string is a quantum bit string that contributes to the measurement result. By retaining the target quantum bit string, the target quantum bit string can contribute to the final ideal result. Therefore, the number of target quantum bit strings is less than or equal to the number of candidate quantum bit strings. Since there are usually invalid candidate quantum bit strings, after deleting the invalid candidate quantum bit strings, the number of target quantum bit strings is less than the number of candidate quantum bit strings, which can reasonably and effectively reduce the quantum bit error correction space, reduce the resource consumption of correction, and effectively improve the efficiency of state measurement.

[0155] The complete process of the quantum bit state measurement method is described in detail below.

[0156] Referring to Figure 9, Figure 9 is a schematic diagram of the architecture of a quantum bit state measurement method provided in an embodiment of the present application, wherein the overall architecture may include a test experiment, an error correction experiment, and a target experiment.

[0157] The following is a detailed description of the test experiment process.

[0158] First, a first measurement probability corresponding to each candidate quantum bit string is obtained, wherein the first measurement probability is obtained by performing multiple state measurements on a quantum bit circuit, the quantum bit circuit includes multiple first quantum bits, and the candidate quantum bit string includes the state of each first quantum bit.

[0159] Then, the candidate quantum bit strings whose first measurement probability is the preset probability are deleted, and the remaining candidate quantum bit strings are determined as the target quantum bit strings; or, the candidate quantum bit strings whose first measurement probability is less than or equal to the probability threshold are deleted, and the remaining candidate quantum bit strings are determined as the target quantum bit strings.

[0160] The process of error correction experiment is described in detail below.

[0161] First, when the states of the first qubit in each target qubit string are all in the first state, the first qubit is deleted, and the remaining first qubit is determined as the second qubit.

[0162] Then, a target number of invalid candidate qubit strings is obtained.

[0163] Next, when the target number is greater than a first number threshold, a plurality of first initial qubit strings are created according to the second qubits, wherein the first number threshold is determined by the number of the second qubits.

[0164] Then, a third measurement probability corresponding to each first initial quantum bit string is obtained, wherein the third measurement probability is obtained by performing multiple state measurements on the quantum calibration circuit corresponding to the first initial quantum bit string.

[0165] Next, the third measurement probability corresponding to the same first initial quantum bit string is used as a column element, and a target matrix is ​​constructed based on multiple column elements.

[0166] Then, the inverse matrix of the target matrix is ​​used as the first correction matrix.

[0167] Next, a virtual qubit space corresponding to the qubit hardware is constructed, where the qubit hardware includes multiple qubit circuits.

[0168] Then, target topology information is obtained, and a plurality of initial virtual qubits are determined from the virtual qubit space according to the target topology information, wherein the initial virtual qubits include the target virtual qubits.

[0169] Then, candidate topology information of each quantum bit circuit is obtained, and circuits whose candidate topology information is the same as the target topology information are screened out from each quantum bit circuit as candidate quantum bit circuits.

[0170] Then, the accuracy information of the candidate quantum bit circuits is obtained, and the target quantum bit circuit is screened out from the candidate quantum bit circuits based on the accuracy information.

[0171] Then, mapping information between the initial virtual qubit and the first qubit in the target qubit circuit is constructed.

[0172] The process of the target experiment is described in detail below.

[0173] First, the quantum bit circuit is controlled to shield the deleted first quantum bit and then the probability to be corrected corresponding to each target quantum bit string is obtained; wherein the probability to be corrected is obtained by performing multiple state measurements on the quantum bit circuit again after shielding the deleted first quantum bit in the quantum bit circuit.

[0174] Then, mapping information corresponding to the target quantum bit circuit is obtained, wherein the mapping information is used to indicate a bit identifier mapping relationship between the second quantum bit and the target virtual quantum bit.

[0175] Then, the first bit identifier of each target virtual quantum bit is obtained, the second bit identifier of the second quantum bit is obtained by matching the first bit identifier and the mapping information, and the corresponding first correction matrix is ​​obtained by matching the identifier string composed of multiple second bit identifiers.

[0176] Then, the target probability corresponding to each target quantum bit string is obtained according to the product of the first correction matrix and the vector to be corrected; or, the inverse matrix of the first correction matrix is ​​fitted with the vector to be corrected based on the least squares method to obtain the target probability corresponding to each target quantum bit string; wherein the vector to be corrected is constructed by multiple probabilities to be corrected.

[0177] Based on this, by obtaining the first measurement probability corresponding to each candidate quantum bit string, invalid candidate quantum bit strings are deleted according to the first measurement probability, and the remaining candidate quantum bit strings are determined as target quantum bit strings. At this time, the target quantum bit string is the quantum bit string that contributes to the measurement result. Accordingly, when creating multiple first initial quantum bit strings based on multiple target quantum bit strings, the number of first initial quantum bit strings created based on candidate quantum bit strings can be reduced, so that when obtaining the first correction matrix obtained by error survey based on multiple first initial quantum bit strings, the dimension of the first correction matrix is ​​reduced. Therefore, the probability to be corrected corresponding to each target quantum bit string is subsequently obtained, and the multiple probabilities to be corrected are corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string. This can reduce the resource consumption of correction under the premise of correcting the state measurement results of the quantum bits in a subsequent processing manner, thereby effectively improving the efficiency of state measurement.

[0178] The quantum bit state measurement method provided in the embodiments of the present application can be applied to a variety of scenarios.

[0179] Taking the calculation of the expected value of a physical quantity as an example, the first measurement probability corresponding to each candidate quantum bit string is obtained, invalid candidate quantum bit strings are deleted according to the first measurement probability, and the remaining candidate quantum bit strings are determined as target quantum bit strings, wherein the first measurement probability is obtained after multiple state measurements are performed on the quantum bit circuit, the quantum bit circuit includes multiple first quantum bits, and the candidate quantum bit string includes the state of each first quantum bit; multiple first initial quantum bit strings are created based on the multiple target quantum bit strings, and a first correction matrix obtained by error survey based on the multiple first initial quantum bit strings is obtained; the probability to be corrected corresponding to each target quantum bit string is obtained, wherein the probability to be corrected is obtained after multiple state measurements are performed on the quantum bit circuit again; the multiple probabilities to be corrected are corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string; each physical quantity is multiplied by the corresponding target probability, and then the average of the multiplication results is calculated to obtain the expected value.

[0180] In addition to calculating the expected values ​​of physical quantities, expected values ​​of chemical quantities, biological values, financial values, etc. can also be calculated, which is not limited in the embodiments of the present application.

[0181] For example, referring to Figure 10, Figure 10 is a columnar schematic diagram of the measurement probability corresponding to the target quantum bit string in the first state provided in an embodiment of the present application.

[0182] Among them, Figure 10 shows the reading error elimination of the GHZ state of 5 quantum bits. The GHZ state includes the |00000> state and the |11111> state. It can be seen that the quantum bit state measurement method provided in the embodiment of the present application has less resource consumption and a more stable and better error elimination effect than the method of not deleting the invalid first quantum bit.

[0183] Referring to Figure 11 , Figure 11 is a bar graph showing the measurement probabilities corresponding to the target qubit string in the second state, as provided in an embodiment of the present application. Figure 11 illustrates the read error elimination for the |00000> state (i.e., a candidate qubit string) and the |10000> state (i.e., a candidate qubit string) of five qubits. It can be seen that the qubit state measurement method provided in an embodiment of the present application consumes less resources and achieves more stable and effective error elimination than the method that does not delete the invalid first qubit.

[0184] Referring to Figure 12, Figure 12 is a broken line diagram of the Pauli operator Z corresponding to different measurement methods provided in the embodiments of the present application. Figure 12 shows the read error elimination of the GHZ state (a special quantum entangled state, a basic building block in many-body quantum entanglement theory, reflecting many-body entanglement in quantum mechanics and demonstrating the non-classical characteristics of quantum entanglement) of five quantum bits. It can be seen that the quantum bit state measurement method provided in the embodiments of the present application has less resource consumption at the expectation value level than other methods, and has a more stable and better error elimination effect.

[0185] Referring to Figure 13 , Figure 13 is a broken line diagram of the expected value corresponding to the Pauli operator X provided in an embodiment of the present application. Figure 13 illustrates read error elimination for three qubits, where qubits 0, 1, and 2 all have the expected value corresponding to the Pauli operator X. This demonstrates that the qubit state measurement method provided in an embodiment of the present application has a stable read error elimination effect in determining the expected value.

[0186] Referring to Figure 14 , a broken line diagram of the expected value corresponding to the Pauli operator Y provided in an embodiment of the present application is shown. Figure 14 illustrates read error elimination for three qubits, where qubits 0, 1, and 2 all have the expected values ​​corresponding to the Pauli operator Y. This demonstrates that the qubit state measurement method provided in an embodiment of the present application has a stable read error elimination effect in determining the expected value.

[0187] Referring to Figure 15 , Figure 15 is a broken line diagram of the expected value corresponding to the Pauli operator Z provided in an embodiment of the present application. Figure 15 illustrates read error elimination for three qubits, where qubits 0, 1, and 2 all have the expected values ​​corresponding to the Pauli operator Z. This demonstrates that the qubit state measurement method provided in an embodiment of the present application has a stable read error elimination effect in determining the expected value.

[0188] It will be appreciated that, although the various steps in the above-mentioned various flow charts are shown in sequence according to the indication of the arrows, these steps are not necessarily performed in sequence according to the order indicated by the arrows. Unless clearly stated in the present embodiment, the execution of these steps does not have strict order restrictions, and these steps can be performed in other orders. Moreover, at least a portion of the steps in the above-mentioned flow charts can include multiple steps or multiple stages, and these steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of the steps or stages in other steps or other steps.

[0189] 16 , which is a schematic diagram of a structure of a quantum bit state measurement device according to an embodiment of the present application. The quantum bit state measurement device 1600 includes:

[0190] A first processing module 1601 is configured to obtain first measurement probabilities corresponding to a plurality of candidate qubit strings, delete some of the candidate qubit strings from the plurality of candidate qubit strings based on the first measurement probabilities, and determine the remaining candidate qubit strings as target qubit strings, wherein the first measurement probabilities are obtained by performing a state measurement on a qubit circuit, the qubit circuit including a plurality of first qubits, and the candidate qubit strings including states of each of the first qubits;

[0191] A second processing module 1602 is configured to create a plurality of first initial qubit strings based on the plurality of target qubit strings, and obtain a first correction matrix obtained by performing error survey based on the plurality of first initial qubit strings;

[0192] An acquisition module 1603 is configured to acquire a probability to be corrected corresponding to each target qubit string, wherein the probability to be corrected is a measurement probability obtained by performing multiple state measurements on the qubit circuit again;

[0193] The correction module 1604 is configured to correct the multiple probabilities to be corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string.

[0194] In some embodiments, the second processing module 1602 is further configured to: when the state of any first quantum bit in each of the target quantum bit strings is the first state, delete any first quantum bit from the multiple first quantum bits, and determine the remaining first quantum bits as second quantum bits; and create multiple first initial quantum bit strings based on the second quantum bits.

[0195] In some embodiments, the acquisition module 1603 is further configured to: after controlling the quantum bit circuit to shield the deleted first quantum bit, obtain the probability to be corrected corresponding to each of the target quantum bit strings; wherein, the probability to be corrected is the measurement probability obtained by performing multiple state measurements on the quantum bit circuit again after shielding the deleted first quantum bit in the quantum bit circuit.

[0196] In some embodiments, the above-mentioned second processing module 1602 is also configured to: obtain a target number of some of the candidate quantum bit strings; when the target number is greater than a first number threshold, create multiple first initial quantum bit strings based on multiple target quantum bit strings, wherein the first number threshold is determined by the number of the second quantum bits.

[0197] In some embodiments, the above-mentioned second processing module 1602 is also configured to: when the target number is less than or equal to the first number threshold, obtain a second correction matrix corresponding to each second quantum bit, wherein the second correction matrix is ​​obtained based on error survey of multiple second initial quantum bit strings, and the second initial quantum bit string includes the state of a single second quantum bit; determine the direct product of multiple second correction matrices as a third correction matrix, and correct the multiple probabilities to be corrected according to the third correction matrix to obtain the target probability corresponding to each target quantum bit string.

[0198] In some embodiments, the above-mentioned second processing module 1602 is also configured to: when the target number is less than or equal to the first number threshold, and the target number is greater than or equal to the second number threshold, obtain the second correction matrix corresponding to each second quantum bit; and / or, when the target number is less than or equal to the third number threshold, obtain the second correction matrix corresponding to each second quantum bit; wherein, the second number threshold is less than the first number threshold, and the third number threshold is less than the second number threshold.

[0199] In some embodiments, there are multiple quantum bit circuits, and each quantum bit circuit corresponds to its own first correction matrix. The probability to be corrected is obtained by performing multiple state measurements on one of the target quantum bit circuits in the multiple quantum bit circuits again. The second quantum bit in the target quantum bit circuit is the quantum bit corresponding to the target virtual quantum bit after quantum circuit compilation. The quantum bit state measurement device also includes a matrix determination module, and the matrix determination module is further configured to: obtain mapping information corresponding to the target quantum bit circuit, wherein the mapping information is used to indicate the bit identifier mapping relationship between the second quantum bit and the target virtual quantum bit; obtain the first bit identifier of each target virtual quantum bit, obtain the second bit identifier of the second quantum bit according to the first bit identifier and the mapping information, and obtain the corresponding first correction matrix according to the identifier string composed of multiple second bit identifiers.

[0200] In some embodiments, the state measurement device of the quantum bit also includes a mapping module (not shown in the figure), and the mapping module is further configured to: construct a virtual quantum bit space corresponding to the quantum bit hardware, wherein the quantum bit hardware includes multiple quantum bit circuits; obtain target topology information, and determine multiple initial virtual quantum bits from the virtual quantum bit space based on the target topology information, wherein the target virtual quantum bit is one of the initial virtual quantum bits; obtain candidate topology information of each quantum bit circuit, and screen out candidate quantum bit circuits whose candidate topology information is the same as the target topology information from multiple quantum bit circuits; obtain accuracy information of the candidate quantum bit circuit, and screen out the target quantum bit circuit from the candidate quantum bit circuit based on the accuracy information; and construct the mapping information between the initial virtual quantum bit and the first quantum bit in the target quantum bit circuit.

[0201] In some embodiments, the second processing module 1602 is further configured to: when each of the first qubits exists in the second state in at least one of the target qubit strings, determine each of the target qubit strings as a first initial qubit string.

[0202] In some embodiments, the acquisition module 1603 is further configured to: obtain a second measurement probability corresponding to each candidate quantum bit string, wherein the second measurement probability is obtained by performing multiple state measurements on the quantum bit circuit again; and use the second measurement probability corresponding to the target quantum bit string as the probability to be corrected.

[0203] In some embodiments, the second processing module 1602 is further configured to: obtain a third measurement probability corresponding to each of the first initial quantum bit strings, wherein the third measurement probability is obtained by performing multiple state measurements on the quantum calibration circuit corresponding to the first initial quantum bit string; determine the third measurement probability corresponding to the same first initial quantum bit string as a column element, and construct a target matrix based on multiple column elements; and determine the inverse matrix of the target matrix as the first correction matrix.

[0204] In some embodiments, the correction module 1604 is further configured to: determine the product of the first correction matrix and the vector to be corrected as the target probability corresponding to each of the target quantum bit strings; and / or, fit the inverse matrix of the first correction matrix to the vector to be corrected based on the least squares method to obtain the target probability corresponding to each of the target quantum bit strings; wherein the vector to be corrected is constructed from multiple probabilities to be corrected.

[0205] In some embodiments, the above-mentioned first processing module 1601 is also configured to: delete the candidate quantum bit strings whose first measurement probability is a preset probability from the multiple candidate quantum bit strings; and / or, delete the candidate quantum bit strings whose first measurement probability is less than or equal to a probability threshold from the multiple candidate quantum bit strings.

[0206] The above-mentioned quantum bit state measurement device 1600 and the quantum bit state measurement method are based on the same inventive concept. By obtaining the first measurement probability corresponding to each candidate quantum bit string, some candidate quantum bit strings are deleted according to the first measurement probability, and the remaining candidate quantum bit strings are determined as target quantum bit strings. At this time, relative to the deleted candidate quantum bit strings, the target quantum bit string is the quantum bit string that contributes to the measurement result. Accordingly, when creating multiple first initial quantum bit strings based on multiple target quantum bit strings, the number of first initial quantum bit strings created based on candidate quantum bit strings can be reduced, so that when obtaining the first correction matrix obtained by error survey based on the multiple first initial quantum bit strings, the dimension of the first correction matrix is ​​reduced. Therefore, the probability to be corrected corresponding to each target quantum bit string is subsequently obtained, and the multiple probabilities to be corrected are corrected according to the first correction matrix to obtain the target probability corresponding to each target quantum bit string. Subsequent processing is performed based on the first correction matrix with reduced dimension, which can reduce the resource consumption of correction while correcting the quantum bit state measurement result, and effectively improve the efficiency of state measurement.

[0207] The electronic device for executing the state measurement method of the quantum bit provided in the embodiment of the present application may be a terminal. Referring to FIG17 , FIG17 is a partial structural block diagram of the terminal provided in the embodiment of the present application, and the terminal includes components such as a camera assembly 1710, a memory 1720, an input unit 1730, a display unit 1740, a sensor 1750, an audio circuit 1760, a wireless fidelity (WiFi) module 1770, a processor 1780, and a power supply 1790. Those skilled in the art will understand that the terminal structure shown in FIG17 does not constitute a limitation of the terminal, and may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0208] The camera assembly 1710 can be used to capture images or videos. Optionally, the camera assembly 1710 includes a front camera and a rear camera. Typically, the front camera is provided on the front panel of the terminal, and the rear camera is provided on the back of the terminal. In some embodiments, there are at least two rear cameras, which are any one of a main camera, a depth of field camera, a wide-angle camera, and a telephoto camera, so as to realize the fusion of the main camera and the depth of field camera to realize the background blur function, the fusion of the main camera and the wide-angle camera to realize panoramic shooting and VR (Virtual Reality) shooting function or other fusion shooting functions.

[0209] The memory 1720 may be used to store software programs and modules. The processor 1780 executes various functional applications and data processing of the terminal by running the software programs and modules stored in the memory 1720 .

[0210] The input unit 1730 may be configured to receive input numbers or characters and generate key signals related to the terminal's settings and function control. For example, the input unit 1730 may include a touch panel 1731 and other input devices 1732.

[0211] The display unit 1740 may be configured to display input information or provided information and various menus of the terminal. The display unit 1740 may include a display panel 1741 .

[0212] The audio circuit 1760 , the speaker 1761 , and the microphone 1762 may provide an audio interface.

[0213] The power source 1790 may be AC ​​power, DC power, disposable batteries, or rechargeable batteries.

[0214] The number of sensors 1750 can be one or more, and the one or more sensors 1750 include but are not limited to: acceleration sensors, gyroscope sensors, pressure sensors, optical sensors, etc. Among them:

[0215] The accelerometer can detect the magnitude of acceleration along the three coordinate axes of the coordinate system established by the terminal. For example, the accelerometer can be used to detect the components of gravity acceleration along the three coordinate axes. The processor 1780 can control the display unit 1740 to display the user interface in a landscape or portrait view based on the gravity acceleration signal collected by the accelerometer. The accelerometer can also be used to collect game or user motion data.

[0216] The gyroscope sensor can detect the device's orientation and rotation angle. It can also work with the accelerometer to capture the user's 3D movements. Based on the data collected by the gyroscope sensor, the processor 1780 can implement the following functions: motion sensing (such as changing the UI based on the user's tilt), image stabilization during shooting, game control, and inertial navigation.

[0217] The pressure sensor can be set on the side frame of the terminal and / or the lower layer of the display unit 1740. When the pressure sensor is set on the side frame of the terminal, it can detect the user's grip signal of the terminal, and the processor 1780 performs left and right hand recognition or shortcut operations based on the grip signal collected by the pressure sensor. When the pressure sensor is set on the lower layer of the display unit 1740, the processor 1780 controls the operability controls on the UI interface based on the user's pressure operation on the display unit 1740. The operability controls include at least one of a button control, a scroll bar control, an icon control, and a menu control.

[0218] The optical sensor is used to detect ambient light intensity. In one embodiment, the processor 1780 can control the display brightness of the display unit 1740 based on the ambient light intensity detected by the optical sensor. For example, when the ambient light intensity is high, the display brightness of the display unit 1740 is increased; when the ambient light intensity is low, the display brightness of the display unit 1740 is decreased. In another embodiment, the processor 1780 can also dynamically adjust the shooting parameters of the camera assembly 1710 based on the ambient light intensity detected by the optical sensor.

[0219] In this embodiment, the processor 1780 included in the terminal can execute the quantum bit state measurement method of the previous embodiment.

[0220] The electronic device for performing the above-mentioned quantum bit state measurement method provided in the embodiments of the present application can also be a server. Referring to FIG18 , FIG18 is a partial structural block diagram of a server provided in the embodiments of the present application. Server 1800 may vary significantly due to different configurations or performances and may include one or more central processing units (CPUs) 1822 (e.g., one or more processors) and memory 1832, and one or more storage media 1830 (e.g., one or more mass storage devices) storing application programs 1842 or data 1844. Memory 1832 and storage medium 1830 may be either ephemeral or persistent storage. The program stored in storage medium 1830 may include one or more modules (not shown), each of which may include a series of instruction operations on server 1800. Furthermore, CPU 1822 may be configured to communicate with storage medium 1830 to execute the series of instruction operations in storage medium 1830 on server 1800.

[0221] The server 1800 may also include one or more power supplies 1826, one or more wired or wireless network interfaces 1850, one or more input and output interfaces 1858, and / or one or more operating systems 1841, such as Windows Server™, Mac OS X™, Unix™, Linux™, FreeBSD™, etc.

[0222] The processor in the server 1800 can be used to execute the state measurement method of the quantum bit.

[0223] An embodiment of the present application also provides a computer-readable storage medium, which is used to store program code, and the program code is used to execute the state measurement method of the quantum bit of each of the aforementioned embodiments.

[0224] The present application also provides a computer program product, comprising a computer program stored in a computer-readable storage medium. A processor of a computer device reads the computer program from the computer-readable storage medium and executes the computer program, causing the computer device to implement the aforementioned quantum bit state measurement method.

[0225] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0226] It should be understood that in this application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0227] It should be understood that in the description of the embodiments of the present application, multiple (or multiple items) means more than two, greater than, less than, exceed, etc. are understood to exclude the number itself, and above, below, within, etc. are understood to include the number itself.

[0228] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0229] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0230] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of circuits or software functional units.

[0231] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0232] It should also be understood that the various implementation methods provided in the embodiments of the present application can be combined arbitrarily to achieve different technical effects.

[0233] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above implementation mode. Technical personnel familiar with the art can also make various equivalent modifications or substitutions under the shared conditions that do not violate the spirit of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. A method for measuring the state of qubits, applied to an electronic device, comprising: Obtaining first measurement probabilities respectively corresponding to a plurality of candidate qubit strings, deleting some of the candidate qubit strings from the plurality of candidate qubit strings according to the first measurement probabilities, and determining the remaining candidate qubit strings as target qubit strings, wherein the first measurement probabilities are obtained after performing state measurement on a qubit circuit, the qubit circuit includes a plurality of first qubits, and the candidate qubit strings include the states of each of the first qubits; Creating a plurality of first initial qubit strings based on the plurality of target qubit strings, and obtaining a first correction matrix obtained by performing error detection based on the plurality of first initial qubit strings; Obtaining a probability to be corrected corresponding to each of the target qubit strings, wherein the probability to be corrected is a measurement probability obtained after performing multiple state measurements on the qubit circuit again; Correcting the probabilities to be corrected of the plurality of target qubit strings respectively according to the first correction matrix to obtain target probabilities corresponding to each of the target qubit strings.

2. The state measurement method according to claim 1, wherein, The obtaining the probability to be corrected corresponding to each of the target qubit strings includes: After controlling the qubit circuit to shield the deleted first qubits, obtaining the probability to be corrected corresponding to each of the target qubit strings; wherein the probability to be corrected is a measurement probability obtained after performing multiple state measurements on the qubit circuit again after shielding the deleted first qubits in the qubit circuit.

3. The state measurement method according to any one of claims 1 to 2, wherein, The creating a plurality of first initial qubit strings based on the plurality of target qubit strings includes: When the state of any of the first qubits in each of the target qubit strings is a first state, deleting any of the first qubits from the plurality of first qubits, and determining the remaining first qubits as second qubits; Creating a plurality of first initial qubit strings according to the second qubits.

4. The state measurement method according to claim 3, wherein, The creating a plurality of first initial qubit strings based on the plurality of target qubit strings includes: Obtaining a target number of some of the candidate qubit strings; When the target number is greater than a first number threshold, creating a plurality of first initial qubit strings based on the plurality of target qubit strings, wherein the first number threshold is determined by the number of the second qubits.

5. The state measurement method according to claim 4, wherein, The state measurement method further includes: When the target number is less than or equal to the first number threshold, obtaining a second correction matrix corresponding to each of the second qubits, wherein the second correction matrix is obtained by performing error detection based on a plurality of second initial qubit strings, and the second initial qubit strings include the states of a single second qubit; Determining a direct product of the plurality of second correction matrices as a third correction matrix, and correcting the probabilities to be corrected of the plurality of target qubit strings according to the third correction matrix to obtain target probabilities corresponding to each of the target qubit strings.

6. The state measurement method according to any one of claims 4-5, wherein, The obtaining the second correction matrix corresponding to each of the second qubits when the target number is less than or equal to the first number threshold includes: When the target quantity is less than or equal to the first quantity threshold and greater than or equal to the second quantity threshold, obtain the second correction matrices corresponding to the respective second qubits; and / or, When the target quantity is less than or equal to the third quantity threshold, obtain the second correction matrices corresponding to the respective second qubits; wherein the second quantity threshold is less than the first quantity threshold, and the third quantity threshold is less than the second quantity threshold.

7. The state measurement method according to claim 3, wherein The number of the qubit circuits is multiple, and each of the qubit circuits corresponds to its own first correction matrix. The probability to be corrected is obtained by performing multiple state measurements on one of the multiple qubit circuits again. The second qubit in the target qubit circuit is the qubit corresponding to the target virtual qubit after quantum circuit compilation. Before correcting the respective probabilities to be corrected according to the first correction matrix to obtain the target probabilities corresponding to the respective target qubit strings, the state measurement method further includes: Obtain the mapping information corresponding to the target qubit circuit, wherein the mapping information is used to indicate the bit identification mapping relationship between the second qubit and the target virtual qubit; Obtain the first bit identification of each of the target virtual qubits, match the second bit identification of the second qubit according to the first bit identification and the mapping information, and match the corresponding first correction matrix according to the identification string formed by the multiple second bit identifications.

8. The state measurement method according to claim 7, wherein, Before obtaining the mapping information corresponding to the target qubit circuit, the state measurement method further includes: Construct a virtual qubit space corresponding to the qubit hardware, wherein the qubit hardware includes multiple qubit circuits; Obtain target topology information, and determine multiple initial virtual qubits from the virtual qubit space according to the target topology information, wherein the target virtual qubit is one of the initial virtual qubits; Obtain the candidate topology information of each of the qubit circuits, and screen out the candidate qubit circuits whose candidate topology information is the same as the target topology information from the multiple qubit circuits; Obtain the accuracy information of the candidate qubit circuits, and screen out the target qubit circuit from the candidate qubit circuits according to the accuracy information; Construct the mapping information between the initial virtual qubit and the first qubit in the target qubit circuit.

9. The state measurement method according to any one of claims 1 to 8, wherein, The creating multiple first initial qubit strings based on the multiple target qubit strings includes: When each of the first qubits exists in at least one of the target qubit strings in the second state, determine each of the target qubit strings as a first initial qubit string.

10. The state measurement method according to any one of claims 1 to 9, wherein, The obtaining the probabilities to be corrected corresponding to the respective target qubit strings includes: Obtain the second measurement probabilities corresponding to each of the candidate qubit strings, where the second measurement probabilities are obtained by performing multiple state measurements on the qubit circuit again; Take the second measurement probability corresponding to the target qubit string as the probability to be corrected.

11. The state measurement method according to any one of claims 1 to 10, wherein, The obtaining of the first correction matrix obtained by performing error detection based on the multiple first initial qubit strings includes: Obtain the third measurement probabilities corresponding to each of the first initial qubit strings, where the third measurement probabilities are obtained by performing multiple state measurements on the quantum calibration circuit corresponding to the first initial qubit string; Determine the third measurement probabilities corresponding to the same first initial qubit string as column elements, and construct a target matrix based on the multiple column elements; Determine the inverse matrix of the target matrix as the first correction matrix.

12. The state measurement method according to any one of claims 1 to 11, wherein, The correcting the probabilities to be corrected respectively according to the first correction matrix to obtain the target probabilities corresponding to each of the target qubit strings includes: Determine the product of the first correction matrix and the vector of probabilities to be corrected as the target probabilities corresponding to each of the target qubit strings; and / or, Based on the least squares method, fit the inverse matrix of the first correction matrix and the vector of probabilities to be corrected to obtain the target probabilities corresponding to each of the target qubit strings; where the vector of probabilities to be corrected is constructed from the multiple probabilities to be corrected.

13. The state measurement method according to any one of claims 1 to 12, wherein, The deleting of some of the candidate qubit strings from the multiple candidate qubit strings according to the first measurement probability includes: Delete from the multiple candidate qubit strings the candidate qubit strings with the first measurement probability being a preset probability; and / or, Delete from the multiple candidate qubit strings the candidate qubit strings with the first measurement probability less than or equal to a probability threshold.

14. A state measurement device for qubits, comprising: A first processing module configured to obtain the first measurement probabilities respectively corresponding to multiple candidate qubit strings, delete some of the candidate qubit strings from the multiple candidate qubit strings according to the first measurement probabilities, and determine the remaining candidate qubit strings as target qubit strings, where the first measurement probabilities are obtained by performing state measurements on a qubit circuit, the qubit circuit includes multiple first qubits, and the candidate qubit strings include the states of each of the first qubits; A second processing module configured to create multiple first initial qubit strings based on the multiple target qubit strings, and obtain a first correction matrix obtained by performing error detection based on the multiple first initial qubit strings; An obtaining module configured to obtain the probabilities to be corrected corresponding to each of the target qubit strings, where the probabilities to be corrected are measurement probabilities obtained by performing multiple state measurements on the qubit circuit again; A correction module configured to correct the probabilities to be corrected respectively according to the first correction matrix to obtain the target probabilities corresponding to each of the target qubit strings.

15. An electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the method for measuring the state of a qubit according to any one of claims 1 to 13 is implemented.

16. A computer-readable storage medium, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the method for measuring the state of a qubit according to any one of claims 1 to 13 is implemented.

17. A computer program product, comprising a computer program, and when the computer program is executed by a processor, the method for measuring the state of a qubit according to any one of claims 1 to 13 is implemented.

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