Qubit gate calibration method and apparatus, and electronic device and medium

Abstract

Provided in the present disclosure are a qubit gate calibration method and apparatus, and an electronic device and a medium. The qubit gate fidelity calibration method comprises: determining a first qubit gate from among a plurality of qubit gates which are used for processing qubits; acquiring a first fidelity of the first qubit gate; determining, from among a plurality of preset fidelity intervals, a first fidelity interval in which the first fidelity is located; on the basis of the first qubit gate, the first fidelity interval and a pre-stored first mapping relationship set, determining, from among the plurality of qubit gates, a second qubit gate to be calibrated, wherein the first mapping relationship set comprises a first mapping relationship between a plurality of first elements and a plurality of second elements, the first elements comprise a plurality of previously calibrated qubit gates and fidelity intervals in which the fidelities of the previously calibrated qubit gates are located, and the second elements comprise preferred qubit gates to be calibrated; on the basis of the first qubit gate, the first fidelity interval and a pre-stored second mapping relationship set, determining a first calibration means from among a plurality of first candidate calibration means, wherein the second mapping relationship set comprises a second mapping relationship between the plurality of first elements and a plurality of third elements, and the third elements comprise the plurality of calibration means; and using the first calibration means to calibrate said second qubit gate. The embodiments of the present disclosure can improve the efficiency of calibrating the fidelities of qubit gates. The embodiments of the present disclosure can be applied to various scenarios such as quantum computing and quantum communication.

Description

Method, device, electronic device and medium for calibrating quantum bit gates

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 6, 2023, with application number 202311146948.3 and invention name “Method, device, electronic device and medium for calibration of quantum bit gate fidelity”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the field of quantum computing, and in particular to a method, device, electronic device, and medium for calibrating a quantum bit gate. Background Art

[0003] The essence of using qubits to perform computational tasks is to perform gate operations on them. However, the results obtained from gate operations often deviate from the expected results. Therefore, qubit gates must be calibrated before executing a computational task to improve the accuracy of the quantum computation results. The degree of closeness between the actual results obtained from a gate operation and the expected results is the fidelity of the qubit gate, and calibration can improve the fidelity of the qubit gate.

[0004] In related technologies, multiple quantum bit gates need to be adjusted according to a pre-defined calibration path. The calibration process is relatively fixed, resulting in low calibration efficiency of the quantum bit gate fidelity.

[0005] Summary of the Invention

[0006] The embodiments of the present disclosure provide a method, device, electronic device, and medium for calibrating a quantum bit gate, which can improve the calibration efficiency of the quantum bit gate fidelity.

[0007] According to one aspect of the present disclosure, a method for calibrating a quantum bit gate is provided, comprising:

[0008] determining a first qubit gate from a plurality of qubit gates for processing a qubit;

[0009] Obtaining a first fidelity of the first quantum bit gate;

[0010] Determining a first fidelity interval in which the first fidelity lies from a plurality of preset fidelity intervals;

[0011] Determining, according to the first qubit gate and the first fidelity interval, a second qubit gate to be calibrated from the plurality of qubit gates based on a pre-stored first mapping relationship set, the first mapping relationship set comprising first mapping relationships between a plurality of first elements and a plurality of second elements, the first elements comprising a plurality of previously calibrated qubit gates and the fidelity intervals within which their fidelities lie, and the second elements comprising a preferred qubit gate to be calibrated;

[0012] Determining, according to the first qubit gate and the first fidelity interval, a first calibration means from a plurality of first candidate calibration means based on a pre-stored second mapping relationship set, the second mapping relationship set comprising second mapping relationships between a plurality of the first elements and a plurality of third elements, the third elements comprising the plurality of calibration means;

[0013] The second quantum bit gate is calibrated using the first calibration means.

[0014] According to one aspect of the present disclosure, a qubit gate calibration device is provided, comprising:

[0015] A first determining unit, configured to determine a first qubit gate from a plurality of qubit gates for processing qubits;

[0016] A first acquiring unit, configured to acquire a first fidelity of the first quantum bit gate;

[0017] a second determining unit, configured to determine a first fidelity interval in which the first fidelity lies from a plurality of preset fidelity intervals;

[0018] The second determining unit is further configured to determine, from the plurality of qubit gates, a second qubit gate to be calibrated based on a pre-stored first mapping relationship set according to the first qubit gate and the first fidelity interval, the first mapping relationship set comprising first mapping relationships between a plurality of first elements and a plurality of second elements, the first elements comprising a plurality of previously calibrated qubit gates and the fidelity intervals within which their fidelities lie, and the second elements comprising a preferred qubit gate to be calibrated;

[0019] The second determining unit is further configured to determine, according to the first qubit gate and the first fidelity interval, a first calibration means from a plurality of first candidate calibration means based on a pre-stored second mapping relationship set, wherein the second mapping relationship set includes second mapping relationships between a plurality of first elements and a plurality of third elements, and the third elements include the plurality of calibration means;

[0020] A calibration unit is configured to calibrate the second quantum bit gate using the first calibration means.

[0021] Optionally, the second determining unit is specifically configured to:

[0022] Obtaining a second fidelity corresponding to each first candidate calibration means, where the second fidelity is a fidelity obtained by calibrating the second qubit gate based on each first candidate calibration means;

[0023] The first calibration method is determined from the plurality of first candidate calibration methods based on the second fidelity corresponding to each of the first candidate calibration methods.

[0024] Optionally, the second determining unit is specifically configured to:

[0025] Obtaining a third fidelity corresponding to the first qubit gate after calibrating the second qubit gate based on each of the first candidate calibration means;

[0026] The first calibration means is determined from the plurality of first candidate calibration means based on the second fidelity and the third fidelity corresponding to each of the first candidate calibration means.

[0027] Optionally, the calibration means calibrates the fidelity of the qubit gate by adjusting one or more of the amplitude, frequency and phase of the radio frequency signal of the qubit;

[0028] The second determining unit is specifically configured to:

[0029] Calculating the average of the amplitudes corresponding to the plurality of first candidate calibration means to obtain a first amplitude average, calculating the average of the frequencies corresponding to the plurality of first candidate calibration means to obtain a first frequency average, and calculating the average of the phases corresponding to the plurality of first candidate calibration means to obtain a first phase average;

[0030] determining a second candidate calibration means according to the first amplitude mean, the first frequency mean, and the first phase mean;

[0031] The first calibration means is determined from a calibration means set consisting of the plurality of first candidate calibration means and the second candidate calibration means.

[0032] Optionally, the second determining unit is further configured to generate the first mapping relationship set and the second mapping relationship set:

[0033] Generating a plurality of data groups based on a plurality of qubit gates and a plurality of fidelity intervals, wherein the data groups are generated by combining any qubit gate with any fidelity interval;

[0034] For each data group, obtaining first fidelity gains corresponding to qubit gates other than the qubit gates in each data group after calibration, wherein the first fidelity gains refer to fidelity gains of the qubit gates other than the qubit gates in each data group after calibration using the selected calibration method;

[0035] Determining, according to the first fidelity gain, a preferred qubit gate to be calibrated corresponding to each data group and a plurality of first candidate calibration means adopted by the preferred qubit gate to be calibrated;

[0036] Generate the first mapping relationship set according to the corresponding relationship between each data group and the qubit gate preferably to be calibrated;

[0037] A second mapping relationship set is generated according to the correspondence between each data group and a plurality of first candidate calibration means.

[0038] Optionally, the second determining unit is further configured to:

[0039] Obtaining a first sum of the fidelities of the plurality of qubit gates before calibration of a third qubit gate in each data group, wherein the third qubit gate is any qubit gate among the plurality of qubit gates;

[0040] Obtaining a second sum of the fidelities of the plurality of qubit gates after the third qubit gate in each data group is calibrated using a third candidate calibration means;

[0041] A first fidelity gain of a third qubit gate in each data group is determined based on a first sum of the fidelities of the plurality of qubit gates and a second sum of the fidelities of the plurality of qubit gates.

[0042] The second determining unit is further configured to:

[0043] When the first fidelity gain of the third quantum bit gate after calibration using the third candidate calibration means is greater than the gain threshold, the third quantum bit gate is determined to be the preferred quantum bit gate to be calibrated corresponding to the data group, and the third candidate calibration means is determined to be the candidate calibration means corresponding to the data group.

[0044] Optionally, the first qubit gate is a qubit gate calibrated before the second qubit gate, and after the first qubit gate is calibrated, other qubit gates in the multiple qubit gates have not been calibrated.

[0045] Optionally, the qubit gate fidelity calibration device further comprises:

[0046] A cyclic calibration unit is used to determine that the second qubit gate is the current qubit gate and cyclically perform the following steps:

[0047] Performing fidelity testing on the plurality of quantum bit gates;

[0048] When it is detected that the fidelity of a qubit gate among the plurality of qubit gates is less than a predetermined fidelity value, determining a qubit gate to be calibrated and a calibration means for calibrating the qubit gate to be calibrated according to the fidelity of the current qubit gate, calibrating the qubit gate to be calibrated based on the calibration means, and updating the current qubit gate based on the qubit gate to be calibrated;

[0049] When the fidelity of the plurality of quantum bit gates is greater than or equal to a predetermined fidelity value, the loop step is terminated.

[0050] Optionally, the first acquiring unit includes:

[0051] Performing an operation corresponding to the first qubit gate on the qubit and obtaining an actual state of the qubit;

[0052] The first fidelity of the first qubit gate is determined based on a difference between the actual state and a desired state.

[0053] Optionally, the first determining unit includes:

[0054] Obtaining an initial fidelity value of each qubit gate in a plurality of qubit gates of a qubit;

[0055] The qubit gate with the highest initial fidelity value is determined to be the first qubit gate.

[0056] According to one aspect of the present disclosure, an electronic device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the above-mentioned method for calibrating the fidelity of a quantum bit gate when executing the computer program.

[0057] According to one aspect of the present disclosure, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and when the computer program is executed by a processor, the method for calibrating the fidelity of a quantum bit gate as described above is implemented.

[0058] According to one aspect of the present disclosure, a computer program product is provided, which includes a computer program. The computer program is read and executed by a processor of a computer device, so that the computer device performs the method for calibrating the fidelity of a quantum bit gate as described above.

[0059] In the embodiment of the present disclosure, an initial first qubit gate is determined from a plurality of qubit gates of a qubit. The first fidelity of the first qubit gate is obtained, and the second qubit gate to be calibrated next and the first calibration means for calibrating the second qubit gate are determined based on the first fidelity. The second qubit gate is calibrated using the first calibration means. In this way, the qubit gate fidelity calibration method provided in the embodiment of the present disclosure can dynamically determine the next qubit gate to be calibrated and the corresponding calibration means based on the fidelity of the current qubit gate, avoiding the limitations of the fixed order calibration on the qubit gates to be calibrated and the calibration effect in the related art, can flexibly calibrate the fidelity of the qubit gate, and can improve the calibration efficiency of the qubit gate fidelity.

[0060] Other features and advantages of the present disclosure will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present disclosure. The purposes and other advantages of the present disclosure can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings are used to provide a further understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation to the technical solution of the present disclosure.

[0062] FIG1 is a system architecture diagram of a system to which a method for calibrating the fidelity of a quantum bit gate is applied according to an embodiment of the present disclosure;

[0063] FIG2A is a schematic diagram of calibrating multiple qubit gates using a fixed calibration path;

[0064] FIG2B is a schematic diagram of a calibration path for calibrating multiple qubit gates according to a qubit gate fidelity calibration method according to an embodiment of the present disclosure;

[0065] FIG3 is an overall flow chart of a method for calibrating the fidelity of a quantum bit gate according to one embodiment of the present disclosure;

[0066] FIG4 is a schematic diagram of entanglement between a qubit unit and an adjacent qubit unit;

[0067] FIG5 is a specific flow chart of step 310 in FIG3 ;

[0068] FIG6 is a specific flow chart of step 320 in FIG3 ;

[0069] FIG7 is a specific flow chart of step 340 in FIG3 ;

[0070] FIG8 is a specific flow chart of step 350 in FIG3 ;

[0071] FIG9 is another specific flow chart of step 350 in FIG3 ;

[0072] FIG10 is a specific flow chart of step 830 in FIG8 ;

[0073] FIG11 is another specific flow chart of step 1020 in FIG10 ;

[0074] FIG12 is a specific flow chart of step 1120 in FIG11 ;

[0075] FIG13 is a flow chart of determining a first calibration means;

[0076] FIG14 is a specific flow chart of generating a first mapping relationship set and a second mapping relationship set;

[0077] FIG15 is a schematic diagram showing changes in the fidelity of multiple qubit gates after calibration of a qubit gate;

[0078] FIG16 is a specific flow chart of calibrating multiple qubit gates based on FIG3 ;

[0079] FIG17 is a detailed diagram of the overall implementation of the method for calibrating the fidelity of a quantum bit gate according to an embodiment of the present disclosure;

[0080] FIG18 is a block diagram of a device for calibrating the fidelity of a quantum bit gate according to an embodiment of the present disclosure;

[0081] FIG19 shows a computer structure diagram of a method for calibrating the fidelity of a quantum bit gate according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0082] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and are not intended to limit the present disclosure.

[0083] Before further explaining the embodiments of the present disclosure in detail, the nouns and terms involved in the embodiments of the present disclosure are explained. The nouns and terms involved in the embodiments of the present disclosure are subject to the following interpretations:

[0084] Quantum computing: Quantum computing is a computing method designed using the principles of quantum mechanics. Its biggest difference from traditional computing is that it uses quantum bits (qubits) rather than traditional binary bits for calculations. Qubits have different properties from traditional binary bits, the most important of which is that they can exist in multiple states simultaneously. Take the famous "Schrödinger's cat" as an example. A cat is trapped in a sealed container containing a small amount of radium and cyanide. The radium decays with a probability. If the radium decays, a mechanism triggers the cyanide bottle, shattering it and killing the cat. If the radium does not decay, the cat survives. According to quantum mechanics, since the radioactive radium exists in a superposition of decayed and undecayed states, the cat should also be in a superposition of dead and alive states. This cat, both dead and alive, is the so-called "Schrödinger's cat." However, a cat that is both dead and alive cannot exist, so the answer cannot be known until the container is opened. However, precisely because quantum bits can represent two states at the same time and carry more information, more data operations can be completed with the same number of quantum bits than classical computing. Therefore, quantum computing greatly improves computer processing speed.

[0085] Quantum: The quantum in "quantum computing" refers to the smallest discrete unit a system can use to calculate output.

[0086] A qubit is the fundamental unit of information in quantum computing. While the role of a qubit 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 superposition of states |0> and |1>—thus significantly increasing computer processing speed. A single qubit is also called a qubit unit.

[0087] Entanglement: Entanglement is the ability of quantum bits (qubits) to correlate with each other. When qubits are entangled, they form a system and influence each other. By adding and entangling more qubits in quantum computing, quantum computers can compute exponentially more information and solve increasingly complex problems.

[0088] Fidelity of qubit gates: Each qubit can employ a variety of different qubit gate operations. When a qubit unit performs a quantum computing task, the qubit gate operation is generally expected to achieve the desired result. This expected result refers to the theoretical gate operation result, also known as the expected gate operation result. However, qubit gates are affected by the external environment. For various reasons, the actual gate operation result (i.e., the observed result of the qubit state after the gate operation) will generally deviate from the expected gate operation result. The degree of closeness between the actual gate operation result and the expected gate operation result is the fidelity of the qubit gate. The higher the fidelity of the qubit gate, the greater the accuracy with which the qubit gate executes the task.

[0089] System architecture and scenario description of the application of the embodiments of the present disclosure

[0090] 1 is a system architecture diagram of a method for calibrating the fidelity of a quantum bit gate according to an embodiment of the present disclosure, which includes a quantum chip 110, a dilution refrigerator 120, a control device 130, and a computer 140.

[0091] Quantum chip 110 is a circuit that acts on physical qubits, controlling them to perform quantum computing tasks and applying different calibration methods to qubit gates during fidelity calibration. Quantum chip 110 contains a large number of qubit units.

[0092] The dilution refrigerator 120 is used to provide an extremely low temperature environment for the quantum chip 110 , which helps to suppress thermal noise in the quantum chip 110 and improve the performance of the quantum chip.

[0093] Control device 130 is used to control quantum chip 110 in performing quantum computing tasks. Control device 130 can be an electronic control system or a microwave control system, for example. Computer 140 is used to issue control instructions to control device 130. For example, a compiled quantum program is compiled by computer 140 to generate instructions and then sent to control device 130. Control device 130 then converts these instructions into electronic or microwave control signals and transmits them to quantum chip 110, which controls the qubits. Computer 140 can be a classical computer, a quantum computer, or a hybrid execution environment of both classical and quantum computers.

[0094] The embodiments of the present disclosure can be applied in various scenarios, such as a scenario where multiple quantum computing tasks are queued for execution.

[0095] When the computer 140 receives a quantum computing task, it needs to determine the quantum bit that can perform the task among the large number of quantum bits in the quantum chip 110. It can be seen that for different quantum computing tasks, the quantum bits used in the quantum chip 110 may be different. Therefore, before the computer 140 executes each quantum computing task, the fidelity of the multiple quantum bit gates corresponding to the corresponding quantum bits can be calibrated to improve the accuracy of the execution results of the quantum computing task. If the computer 140 receives multiple quantum computing tasks, the fidelity of the multiple quantum bit gates corresponding to the quantum bits used in each quantum computing task can be calibrated in turn. If the fidelity calibration of the quantum bit gate of a quantum computing task takes a long time, it will also delay the execution of other quantum computing tasks, which undoubtedly brings challenges to the calibration efficiency of the quantum bit gate fidelity.

[0096] In the related art, for a quantum computing task, the fidelity calibration process for multiple qubit gates corresponding to the qubits used in the task is pre-set. Specifically, a directed acyclic graph (DAG) can be used to represent the pre-set qubit gate fidelity calibration process, where a node in the DAG represents a qubit gate and a corresponding set fidelity calibration target, and an edge in the DAG represents the dependency relationship between nodes. That is, only when the fidelity calibration of the qubit gate in the previous node reaches the set fidelity calibration target can the fidelity calibration of the qubit gate in the next node be performed. For example, as shown in Figure 2A, there may be four qubit gates that need to be calibrated: Gate I, Gate X, Gate Y, and Gate H. When the fidelity of Gate X reaches 80%, according to the pre-set path, the fidelity of Gate Y is calibrated using calibration method A to bring the fidelity of Gate Y to 85%. After the fidelity of Gate Y reaches 85%, the fidelity of Gate H is calibrated using calibration method B to bring the fidelity of Gate H to 90%. After the fidelity of gate H reaches 90%, calibration method C is used to calibrate the fidelity of gate I to 85%. Similarly, calibration method D is used to increase the fidelity of gate X to 90%, calibration method E is used to increase the fidelity of gate Y to 95%, calibration method F is used to increase the fidelity of gate X to 95%, calibration method G is used to increase the fidelity of gate I to 95%, and calibration method H is used to increase the fidelity of gate H to 95%. Using this fixed calibration path and method prevents the calibration process from exploring other paths with better calibration results. For example, as shown in Figure 2B, when the fidelity of gate X reaches 80%, calibration method M can be used to directly calibrate the fidelity of gate H to 95%; when the fidelity of gate H reaches 95%, calibration method N can be used to calibrate the fidelity of gate X to 95%; when the fidelity of gate X reaches 95%, calibration method G can be used to calibrate the fidelity of gate I to 95%; and when the fidelity of gate I reaches 95%, calibration method P can be used to calibrate the fidelity of gate Y to 95%. The calibration path shown in Figure 2A requires a total of eight calibrations, while the calibration path in Figure 2B only requires four. Clearly, the calibration path in Figure 2B is more efficient, but the related art solutions do not consider this more effective calibration path, resulting in lower calibration efficiency. When multiple quantum computing tasks are queued for execution, it is impossible to quickly calibrate each quantum computing task, affecting the execution efficiency of the quantum computing tasks.Moreover, in the related art method of calibrating the fidelity of quantum bit gates based on DAG, there may also be a situation where the fidelity of the quantum bit gate in the current node cannot be calibrated to reach the fidelity target set in the node. In this case, since the task of the current node has not been completed, the next node that depends on the node cannot perform the corresponding calibration work, resulting in the calibration process being stuck, which greatly reduces the calibration efficiency of the quantum bit gate fidelity.

[0097] The disclosed embodiments can determine the next qubit gate to be calibrated and the calibration method to be used based on the fidelity of the current qubit gate. Referring to the qubit gates in Figures 2A and 2B, if the current qubit gate is gate X with a fidelity of 80%, the one that provides the best calibration effect among gates I, Y, and H is determined as the next qubit gate to be calibrated. The calibration method that can most effectively improve the fidelity of the next qubit gate to be calibrated is then determined from multiple calibration methods. According to the fixed path in Figure 2A, when the fidelity of gate X reaches 80%, calibration method A must be used to calibrate gate Y to bring the fidelity of gate Y to 85%. However, through the disclosed embodiments, it can be found that when the fidelity of gate X reaches 80%, calibrating gate H is more effective, and calibration method M can directly increase the fidelity of gate H to 95%. Therefore, the disclosed embodiments significantly improve the efficiency of qubit gate fidelity calibration. In scenarios where multiple quantum computing tasks are queued for execution, this reduces the calibration time required for each quantum computing task, thereby accelerating the execution of multiple quantum computing tasks.

[0098] General description of the embodiments of the present disclosure

[0099] According to one embodiment of the present disclosure, a method for calibrating the fidelity of a quantum bit gate is provided.

[0100] A qubit gate operates by applying a radio frequency modulation signal to the qubit to control its state. The qubit's state is a superposition of state |0> and state |1>, with a probability α for state |0> and a probability β for state |1>. By applying different radio frequency modulation signals to change the qubit's superposition state, the values ​​of α and β change accordingly. However, regardless of the change, the two satisfy

[0101] α 2 +β 2=1. Using qubits to perform quantum computing tasks is essentially to perform a large number of gate operations on qubits according to the quantum computing tasks. There are many types of qubit gates, such as I, X, Y, and H. Different qubit gates apply different RF modulation signals, and the state of the qubit after the gate operation is also different. For example, the X gate will swap the probabilities of the qubit state |0> and state |1>, that is, the probability corresponding to state |0> becomes β, and the probability corresponding to state |1> becomes α. The H gate will change the probability corresponding to the qubit state |0> to The probability corresponding to state |1> becomes This superposition state of a qubit is the desired state after a gate operation. However, in practice, the state obtained after a qubit gate operation often falls short of the desired state. Therefore, fidelity is used to measure the difference between the actual state and the desired state after a qubit gate operation. A higher fidelity indicates a smaller difference. The calibration process of a qubit gate is the process of improving the fidelity of the qubit gate.

[0102] When calibrating the fidelity of multi-qubit gates, it's important to consider the calibration order and applied calibration methods. In related technologies, the calibration order and applied calibration methods for multi-qubit gates are fixed, and the fidelity improvement after each calibration is also fixed. This prevents the exploration of more effective calibration paths and corresponding calibration methods during the calibration process, reducing calibration efficiency.

[0103] According to one embodiment of the present disclosure, a method for calibrating a quantum bit gate is provided.

[0104] The calibration method of the quantum bit gate in the embodiment of the present disclosure can be executed on a server or on a terminal.

[0105] As shown in FIG3 , the calibration method 300 of a quantum bit gate according to an embodiment of the present disclosure includes:

[0106] Step 310: Determine a first qubit gate from a plurality of qubit gates for processing qubits;

[0107] Step 320: Obtain a first fidelity of the first qubit gate;

[0108] Step 330: Determine a first fidelity interval in which the first fidelity is located from a plurality of preset fidelity intervals;

[0109] Step 340: Determine, based on the first qubit gate and the first fidelity interval, a second qubit gate to be calibrated from the plurality of qubit gates based on a pre-stored first mapping relationship set, the first mapping relationship set comprising first mapping relationships between a plurality of first elements and a plurality of second elements, the first elements comprising a plurality of previously calibrated qubit gates and the fidelity intervals within which their fidelities lie, and the second elements comprising a preferred qubit gate to be calibrated;

[0110] Step 350: Determine a first calibration means from a plurality of first candidate calibration means based on a pre-stored second mapping relationship set according to the first qubit gate and the first fidelity interval, wherein the second mapping relationship set includes second mapping relationships between a plurality of first elements and a plurality of third elements, and the third elements include the at least one calibration means;

[0111] Step 360: Calibrate the second quantum bit gate using the first calibration method.

[0112] Steps 310 to 360 are described in detail below.

[0113] Detailed description of step 310

[0114] For a quantum computing task, it is necessary to select a qubit unit that can perform the quantum computing task from the large number of qubit units in the quantum chip 110. Multiple qubit units form a qubit network by interconnecting two adjacent qubits. Two interconnected qubit units will become entangled and influence each other. When performing quantum computing, it is necessary to utilize each qubit unit in the qubit network to perform operations, and it is also necessary to utilize the entanglement between two interconnected qubit units to perform operations. As shown in Figure 4, qubit unit A is entangled with qubit unit B, and qubit unit B is entangled with qubit unit C. When performing quantum computing, qubit unit A, qubit unit B, qubit unit C, the entanglement of qubit units A and B, and the entanglement of qubit units B and C need to be respectively performed through multiple qubit gates for gate operations. Therefore, it is necessary to calibrate the fidelity of the gate operation for the entanglement between each qubit unit and the qubit unit. Therefore, the qubits in the embodiments of the present disclosure can be qubit units or entanglement between qubit units.

[0115] The multiple qubit gates corresponding to a qubit are multiple qubit gate operations performed on the qubit. The difference between entanglement between qubit units and qubit units is that different qubit gates are applicable to the two. If the qubit is a qubit unit, the above-mentioned gates I, X, Y, and H can be used to perform gate operations on the qubit, so these four gates are the qubit gates to be calibrated for the qubit. If the qubit gate is the entanglement between qubit units, the gate operation needs to consider the states of the two qubit units. Assume that there are two adjacent qubit units A and B, and the probability corresponding to the state of A |0> is α A , the probability corresponding to state |1> is β A , the probability corresponding to the state |0> of B is α B , the probability corresponding to state |0> is β B Assume there are two gate operations, gate M and gate N, gate M will convert α A α B Convert to alpha A β B , change α A β B Convert to beta A α B , β A α B Convert to beta A β B , β A β B Convert to alpha A α B Gate N will convert α A α B Convert to (α A α B +α A β B +β A α B +β A β B ) / 4, and α A β B Convert to (α A α B +α A β B +β A α B +β A β B ) / 4, and β A α B Convert to (α A α B +α A β B +β A α B +βA β B ) / 4, and β A β B Convert to (α A α B +α A β B +β A α B +β A β B ) / 4.

[0116] The first qubit gate can be an initial qubit gate determined from multiple qubit gates. Since the multiple qubit gates of a qubit all require calibration, any qubit gate can serve as the first qubit gate. Therefore, the first qubit gate can be determined from the multiple qubit gates of a qubit by random selection.

[0117] In another embodiment, as shown in FIG5 , step 310 of determining a first qubit gate from a plurality of qubit gates includes:

[0118] Step 510: Obtain an initial fidelity value of each qubit gate in the plurality of qubit gates;

[0119] Step 520: Determine the qubit gate with the highest initial fidelity value as the first qubit gate.

[0120] In this embodiment, the first qubit gate is determined based on the initial fidelity values ​​of multiple qubit gates. The initial fidelity value is the fidelity value of the qubit gate before calibration. The fidelity of a qubit gate is primarily affected by noise interference from the external environment. Therefore, if the external environment is stable, the fidelity value of an uncalibrated qubit gate will not fluctuate significantly. Therefore, the initial fidelity value of the qubit gate can be determined experimentally in a stable environment so that it can be readily retrieved when needed. For example, experimentally, the initial fidelity value of gate X is generally stable at 80%, with slight fluctuations of 1%, while the initial fidelity value of gate Y is generally stable at 85%, with slight fluctuations of 1%. Therefore, 80% can be used as the initial fidelity value for gate X, and 85% can be used as the initial fidelity value for gate Y. This improves the efficiency of obtaining the initial fidelity value for each qubit gate.

[0121] Since the qubit gate fidelity calibration process is a process that causes the fidelity of multiple qubit gates to spiral upward, using the qubit gate with the highest initial fidelity value as the first qubit gate can set a higher baseline for the qubit gate fidelity calibration process, thereby improving the efficiency of qubit gate fidelity calibration. Therefore, in the disclosed embodiments, after obtaining the initial fidelity value of each qubit gate, the qubit gate with the highest initial fidelity value can be set as the first qubit gate, setting a higher baseline for the qubit gate fidelity calibration process, thereby further improving the efficiency of qubit gate fidelity calibration.

[0122] Detailed description of step 320

[0123] In step 320 , a first fidelity of the first qubit gate is obtained.

[0124] In the embodiment of steps 510-520, the initial fidelity value of the qubit gate can be determined experimentally in a stable environment in advance. If the first fidelity of the first qubit gate is obtained based on the embodiment of steps 510-520, the initial fidelity value corresponding to the first qubit gate can be used as the first fidelity directly when the first qubit gate is determined. If the first qubit gate is obtained by random sampling, the initial fidelity value of the first qubit gate stored in advance can also be retrieved as the first fidelity. The advantage of using the initial fidelity of the first qubit gate as the first fidelity is that the first fidelity can be obtained faster and more efficiently.

[0125] However, in subsequent steps, the second qubit gate and the first calibration method need to be determined based on the first fidelity. Therefore, the accuracy of the first fidelity is very important. Therefore, in another embodiment, as shown in FIG6 , step 320 includes:

[0126] Step 610: Execute the operation corresponding to the first qubit gate on the qubit and obtain the actual state of the qubit;

[0127] Step 620: Determine a first fidelity of the first qubit gate based on a difference between the actual state of the qubit and the expected state of the qubit.

[0128] The first fidelity represents the difference between the actual state of the qubit and the expected state after the operation corresponding to the first qubit gate is performed on the qubit. The expected state refers to the state of the qubit after the operation corresponding to the first qubit gate is performed on the qubit in an ideal environment without any noise and interference. For example, the first qubit gate is gate X. Performing gate X on the qubit will swap the probabilities of the two states |0> and |1>, generating a new superposition state. In other words, if the probability of the qubit state |0> is 4 / 5 and the probability of the state |1> is 3 / 5, then after performing the operation corresponding to gate X on the qubit, the expected state of the qubit is state |0> with a probability of 3 / 5 and state |1> with a probability of 4 / 5. However, due to interference in the actual computing environment, the expected state is often not achieved after executing the first qubit gate. For example, after executing gate X, the actual state of the qubit is state |0> with a probability of 3 / 4 and state |1> with a probability of 4 / 5. This shows that there is a difference between the actual state of the quantum bit and the expected state.

[0129] The first fidelity of the first qubit gate is determined based on the difference between the actual state of the qubit and the expected state of the qubit as shown in Formula 1: F(ε,μ)=Tr[ε(|0><1|)μ(|0><1|)] Formula (1).

[0130] In Formula 1, ε is the actual state of the quantum bit after the gate operation of the first quantum bit gate; μ is the expected state; F is the difference between the actual state and the expected state, that is, the fidelity; Tr refers to the trace operation of the actual state and the expected state to obtain the first fidelity of the first quantum bit gate.

[0131] This embodiment obtains the actual state by performing the operation corresponding to the first quantum bit gate on the quantum bit, and then determines the first fidelity based on the difference between the actual state and the expected state, ensuring that the first fidelity can reflect the accuracy of the gate operation performed by the current first quantum bit gate, thereby improving the accuracy of obtaining the first fidelity.

[0132] Detailed description of step 330

[0133] In step 330 , a first fidelity interval in which the first fidelity lies is determined from a plurality of preset fidelity intervals.

[0134] Different fidelity intervals correspond to the second qubit gate to be calibrated and also correspond to the first calibration method. Therefore, it is necessary to determine the first fidelity interval in which the first fidelity lies.

[0135] In this embodiment, the fidelity can be divided into intervals. For example, the first fidelity interval can be divided into 5% increments, including: [0, 5%), [5%, 10%), ..., [90%, 95%), [95%, 100%). If the first fidelity is 81%, then the first fidelity interval is [80%, 85%).

[0136] This application does not limit the step value of the fidelity interval. Those skilled in the art can select a suitable step value based on the accuracy of quantum bit calibration. For example, if the accuracy is high, the step value can be smaller; if the accuracy is low, the step value can be appropriately increased.

[0137] Detailed description of step 340

[0138] In step 340, according to the first qubit gate and the first fidelity interval, based on a pre-stored first mapping relationship set, a second qubit gate to be calibrated is determined from a plurality of qubit gates, the first mapping relationship set including a first mapping relationship between a plurality of first elements and a plurality of second elements, the first element including a plurality of previously calibrated qubit gates and the fidelity intervals in which their fidelities lie, and the second element including the preferred qubit gate to be calibrated.

[0139] Specifically, the pre-stored first mapping relationship set includes first mapping relationships between a plurality of first elements and a plurality of second elements, wherein the first elements include a plurality of previously calibrated qubit gates and the fidelity intervals within which their fidelities lie, and the second elements include a preferred qubit gate to be calibrated. After determining the first qubit gate and the first fidelity interval within which the first qubit gate lies, the first mapping relationship set is searched based on the first qubit gate and the first fidelity interval to obtain the second qubit gate to be calibrated corresponding to the first qubit gate and the first fidelity interval.

[0140] The first mapping relationship set is determined in advance so that the first mapping relationship set can be directly searched according to the first element to find the second element corresponding to the first element, that is, the first mapping relationship set can be searched according to the first quantum bit gate and the first fidelity interval to obtain the second quantum bit gate to be calibrated corresponding to the first quantum bit gate and the first fidelity interval.

[0141] The first mapping relationship set may be stored in various forms such as a mapping relationship table and text.

[0142] In one embodiment, as shown in FIG7 , step 340 includes:

[0143] Step 710: Obtain a first mapping relationship set;

[0144] Step 720: According to the first qubit gate and the first fidelity interval, search and obtain a second qubit gate to be calibrated in the first mapping relationship set.

[0145] It should be understood that the present application does not limit the storage location of the first mapping relationship set. The first mapping relationship set may be stored on a local device, such as the terminal device executing method 300, or on a cloud device, or on another device. Obtaining the first mapping relationship set includes obtaining the first mapping relationship set stored locally or stored on a cloud device.

[0146] In this embodiment, the first mapping relationship set is stored in the form of a mapping relationship table. The first mapping relationship table includes first mapping relationships between multiple first elements and multiple second elements. The first elements include multiple previously calibrated qubit gates and the fidelity intervals within which their fidelities fall. The second elements include the preferred qubit gates to be calibrated. Table 1 shows an example of the first mapping relationship table.

[0147] Table 1 First mapping relationship table

[0148] Based on the first mapping relationship table in Table 1, when the first qubit gate is gate X and the first fidelity interval is [80%, 85%), the qubit gate to be calibrated is gate Y.

[0149] The first mapping relationship table eliminates the need to traverse all qubit gates each time a qubit gate to be calibrated is determined, thereby improving the efficiency of determining the second qubit gate based on the first fidelity interval of the first qubit gate.

[0150] The first qubit gate is a qubit gate that was calibrated before the second qubit gate, and no other qubit gates in the plurality of qubit gates have been calibrated since the first qubit gate was calibrated. The first mapping relationship table is generated by determining the qubit gate to be calibrated that has the best calibration effect based on a combination of qubit gates and fidelity intervals, and generating the first mapping relationship.

[0151] Detailed description of step 350

[0152] In step 350, according to the first quantum bit gate and the first fidelity interval, based on a pre-stored second mapping relationship set, a first calibration means is determined from multiple first candidate calibration means, the second mapping relationship set includes second mapping relationships between multiple first elements and multiple third elements, and the third elements include the at least one calibration means.

[0153] Specifically, the pre-stored second mapping relationship set includes second mapping relationships between a plurality of first elements and a plurality of third elements, wherein the first elements include a plurality of previously calibrated qubit gates and the fidelity intervals within which their fidelities lie, and the third elements include at least one calibration method. After determining the first qubit gate and the first fidelity interval within which the first qubit gate lies, the second mapping relationship set is searched based on the first qubit gate and the first fidelity interval to obtain the at least one calibration method corresponding to the first qubit gate and the first fidelity interval.

[0154] The second mapping relationship set is determined in advance so that the second mapping relationship set can be directly searched according to the first element to find the third element corresponding to the first element, that is, the second mapping relationship set can be searched according to the first quantum bit gate and the first fidelity interval to obtain at least one calibration means corresponding to the first quantum bit gate and the first fidelity interval.

[0155] The second mapping relationship set may be stored in various forms such as a mapping relationship table and text.

[0156] In the second mapping relationship set, the calibration means corresponding to the first fidelity interval of the first qubit gate can be one or more. If there is one, then the calibration means is directly used as the first calibration means. If there are multiple, as shown in Figure 8, step 350 includes:

[0157] Step 810: Obtain a second mapping relationship set;

[0158] Step 820: Search and obtain a plurality of first candidate calibration methods in the second mapping relationship set according to the first qubit gate and the first fidelity interval;

[0159] Step 830: Determine a first calibration method from a plurality of first candidate calibration methods.

[0160] It should be understood that the present application does not limit the storage location of the second mapping relationship set. The second mapping relationship set may be stored on a local device, such as the terminal device executing method 300, or on a cloud device, or on another device. Obtaining the second mapping relationship set includes obtaining the second mapping relationship set stored locally or stored on a cloud device.

[0161] In this embodiment, the second mapping relationship set is stored in the form of a mapping relationship table. The second mapping relationship table includes first mapping relationships between multiple first elements and multiple third elements. The first elements include multiple previously calibrated qubit gates and the fidelity intervals within which their fidelities fall. The third elements include multiple first candidate calibration methods. Table 2 shows an example of the second mapping relationship table.

[0162] Table 2 Second mapping relationship table

[0163] Based on the second mapping relationship table in Table 2, when the first quantum bit gate is gate X and the first fidelity interval is [80%, 85%), the first candidate calibration means include A, E and M.

[0164] Since the calibration method calibrates the fidelity of the qubit gate by adjusting the RF signal of the qubit, the calibration method can be a combination of different properties of the RF signal adjustment method.

[0165] In one embodiment, the qubit gate calibration method further includes: generating multiple calibration means based on a combination of multiple amplitude values, multiple frequency values, and multiple phase values.

[0166] In the disclosed embodiments, since qubit gates are logical operations based on qubits, the fidelity of the multiple qubit gates corresponding to the qubits is a property of the qubits themselves. In the disclosed embodiments, the qubits can specifically be radio frequency signals, which have three main parameters: amplitude, frequency, and phase. Calibrating the fidelity of the qubit gates essentially involves adjusting the properties of the qubits themselves to increase the fidelity of the qubit gates. Adjusting the properties of the qubits in the disclosed embodiments involves adjusting any one or more of the amplitude, frequency, or phase of the radio frequency signal corresponding to the qubits. Therefore, in the disclosed embodiments, the specific operation of the calibration method for calibrating the fidelity of the qubit gates is to adjust any one or more of the amplitude, frequency, or phase of the radio frequency signal corresponding to the qubits. The specific values ​​of these three parameters vary depending on the calibration method. For example, the first calibration method may increase the frequency of the radio frequency signal corresponding to the qubit by x Hz; or the second calibration method may adjust the phase of the radio frequency signal by 20 degrees. Based on the different values ​​and combinations of the above three parameters, multiple calibration methods can be generated. The calibration goal of each calibration method is to approach the fidelity of the corresponding quantum bit gate to 100%.

[0167] In step 820, after obtaining the first mapping relationship table, a plurality of first candidate calibration means are searched in the second mapping relationship table based on the first quantum bit gate and the first fidelity interval.

[0168] Taking the second mapping relationship table in Table 2 as an example, if the first quantum bit gate is gate H and the first fidelity interval is [80%, 85%), then the multiple first candidate calibration means are calibration means C and calibration means N.

[0169] Calibration methods are generated based on different dimensions of the RF signal, such as amplitude, frequency, and phase. Each dimension can have any value, and the calibration methods cannot encompass all possible calibration methods. Therefore, after obtaining a first candidate calibration method, additional calibration methods can be generated based on multiple first candidate calibration methods to increase the number of candidate calibration methods.

[0170] In one embodiment, the calibration means calibrates the fidelity of the qubit gate by adjusting one or more of the amplitude, frequency, and phase of the qubit's radio frequency signal; as shown in FIG9 , after step 820, further comprising:

[0171] Step 921: Calculate the average of the amplitudes corresponding to the plurality of first candidate calibration means to obtain a first amplitude average, calculate the average of the frequencies corresponding to the plurality of first candidate calibration means to obtain a first frequency average, and calculate the average of the phases corresponding to the plurality of first candidate calibration means to obtain a first phase average.

[0172] Step 922: Determine a second candidate calibration method according to the first amplitude mean, the first frequency mean, and the first phase mean;

[0173] Step 930: Determine a first calibration means from a plurality of first candidate calibration means and second candidate calibration means.

[0174] In this embodiment, the calibration means is a combination of one or more of amplitude, frequency and phase. If there is only one, such as frequency, then this calibration means only adjusts the frequency of the RF signal of the quantum bit. If there are multiple, then the parameters of multiple dimensions of the RF signal of the quantum bit are adjusted.

[0175] Since all first candidate calibration methods can produce a good calibration effect on the second qubit gate, the second candidate calibration method generated based on the multiple dimension values ​​of the first candidate calibration method may also produce a good calibration effect on the second qubit gate. The amplitudes of the multiple first candidate calibration methods are averaged to obtain a first amplitude mean, the frequencies are averaged to obtain a first frequency mean, and the phases are averaged to obtain a first phase mean. For example, the second candidate calibration method generated based on the multiple first candidate calibration methods is shown in Table 3.

[0176] Table 3 Example table of generating second candidate calibration means based on multiple first candidate calibration means

[0177] According to calibration means A to calibration means D in Table 3, the amplitude, frequency and phase are averaged in turn, and the second candidate calibration means is to increase the amplitude by 3dB, reduce the frequency by 4MHz, and reduce the phase by 8 degrees.

[0178] Then, the first calibration means may be determined from the calibration means set consisting of the first candidate calibration means and the second candidate calibration means.

[0179] In the aforementioned embodiment, each first candidate calibration method in the second mapping table includes a calibration weight. Therefore, the second candidate calibration method can be determined based on the amplitude, frequency, and phase of the multiple first candidate calibration methods. Alternatively, a weighted average of the amplitudes of the multiple first candidate calibration methods can be calculated to obtain a second amplitude mean value, a weighted average of the frequencies of the multiple first candidate calibration methods can be calculated to obtain a second frequency mean value, and a weighted average of the phases of the multiple first candidate calibration methods can be calculated to obtain a second phase mean value. The second candidate calibration method can then be determined based on the second amplitude mean value, the second frequency mean value, and the second phase mean value.

[0180] Because a higher calibration weight indicates a greater improvement in the fidelity of the second qubit gate by the first candidate calibration method, when generating the second candidate calibration method, the dimension value can be shifted toward the first candidate calibration method with a higher weight. For example, based on the calibration weight, the second candidate calibration method is generated from multiple first candidate calibration methods as shown in Table 4.

[0181] Table 4 Example table of generating second candidate calibration means based on multiple first candidate calibration means

[0182] According to calibration means A to calibration means D in Table 4, based on the calibration weight of each first candidate calibration means, the weighted average values ​​of amplitude, frequency and phase are calculated in turn, and the second calibration means is obtained as follows: the amplitude is increased by 2.86dB, the frequency is reduced by 3.5MHZ, and the phase is reduced by 7.625 degrees.

[0183] The advantage of using weighted average to generate the second candidate calibration means is that the second candidate calibration means can be made closer to the first candidate calibration means, which can bring better calibration effect for the fidelity of the second quantum bit gate, which is beneficial to improving the calibration effect of the second candidate calibration means on the fidelity of the second quantum bit gate.

[0184] In this embodiment, a second candidate calibration means is generated based on multiple first candidate calibration means. Compared with multiple first candidate calibration means, the second candidate calibration means may bring better calibration effects, improve the ability to explore better calibration means, and thus improve the calibration efficiency of multiple quantum bit gate fidelity.

[0185] In step 830, a first calibration method is determined from the plurality of first candidate calibration methods. Based on one of the aforementioned embodiments, the second mapping table records the calibration weight of each first candidate calibration method. Therefore, the first calibration method can be determined directly from the plurality of first candidate calibration methods based on the calibration weight.

[0186] In another embodiment, as shown in FIG10 , step 830 includes:

[0187] Step 1010: Determine a second fidelity corresponding to each first candidate calibration method;

[0188] Step 1020: Determine a first calibration means from a plurality of first candidate calibration means based on the second fidelity corresponding to each first candidate calibration means.

[0189] Optionally, determining the second fidelity corresponding to each first candidate calibration method includes:

[0190] Applying each first candidate calibration means to the qubit, performing a gate operation on the qubit using the second qubit gate, and obtaining an actual gate operation result;

[0191] The second fidelity corresponding to each first candidate calibration means is determined based on the actual gate operation result and the expected gate operation result, wherein the expected gate operation result refers to the theoretical operation result of performing a gate operation on the quantum bit using the second quantum bit gate.

[0192] Optionally, determining the first calibration means from a plurality of first candidate calibration means based on the second fidelity corresponding to each first candidate calibration means includes:

[0193] From the second fidelities corresponding to multiple first candidate calibration means, the first candidate calibration means with the largest second fidelity is selected as the first calibration means.

[0194] In this embodiment, each first candidate calibration means is used to calibrate the second qubit gate of the qubit, and the first candidate calibration means with the best calibration effect is used as the first calibration means, thereby improving the accuracy of determining the first calibration means.

[0195] Since calibrating a qubit gate may affect the fidelity of other qubit gates, based on the embodiment of steps 1010 to 1020, in one embodiment, as shown in FIG11 , after step 1010, the following steps are further included:

[0196] Step 1110: Obtain a third fidelity corresponding to the first qubit gate after calibrating the second qubit gate based on each first candidate calibration means;

[0197] Step 1120: Determine a first calibration means from a plurality of first candidate calibration means based on the second fidelity and the third fidelity corresponding to each first candidate calibration means.

[0198] Optionally, obtaining a third fidelity corresponding to the first qubit gate after calibrating the second qubit gate based on each first candidate calibration means includes:

[0199] After calibrating the second qubit gate using each first candidate calibration means, the first qubit gate can be used to perform gate operations on the qubit to obtain actual gate operation results;

[0200] The third fidelity of the first qubit gate is determined based on the actual gate operation result and the expected gate operation result. The expected gate operation result refers to the theoretical operation result of performing a gate operation on the qubit using the first qubit gate.

[0201] In the embodiment of the present disclosure, after determining the second fidelity corresponding to each calibration means (indicating the calibration effect of the calibration means on the second quantum bit gate), the third fidelity corresponding to each calibration means can be further determined (indicating the impact of the calibration means on the fidelity of the first quantum bit gate when calibrating the second quantum bit gate), and then the optimal candidate calibration means can be further comprehensively evaluated based on the second fidelity and the third fidelity to be used as the first calibration means.

[0202] In one embodiment, as shown in FIG12 , step 1120 includes:

[0203] Step 1210: Determine a third fidelity gain corresponding to each first candidate calibration means based on the fidelity of the second qubit gate before calibration and the second fidelity corresponding to each first candidate calibration means;

[0204] Step 1220: Determine a fourth fidelity gain corresponding to each first candidate calibration means based on the first fidelity of the first qubit gate and the third fidelity corresponding to each first candidate calibration means;

[0205] Step 1230: Determine a first calibration means from a plurality of first candidate calibration means based on the third fidelity gain and the fourth fidelity gain corresponding to each first candidate calibration means.

[0206] In this embodiment, for each first candidate calibration method, the difference in fidelity before and after calibration of the second qubit gate is obtained as the third fidelity gain, and the difference in fidelity before and after calibration of the first qubit gate is obtained as the fourth fidelity gain. For example, before calibration of the second qubit gate, the fidelity of the second qubit gate is 80%, and the first fidelity of the first qubit gate is 83%. After calibration of the second qubit gate using a first candidate calibration method, the second fidelity of the second qubit gate is 92%, and the third fidelity of the first qubit gate is 80%. In this case, the third fidelity gain corresponding to the first candidate calibration method is 92% - 80% = 12%, and the fourth fidelity gain is 80% - 83% = -3%.

[0207] Optionally, determining the first calibration means from a plurality of first candidate calibration means based on the third fidelity gain and the fourth fidelity gain corresponding to each first candidate calibration means includes:

[0208] The third fidelity gain and the fourth fidelity gain corresponding to each first candidate calibration means are directly added together, and the first candidate calibration means with the largest sum is used as the first calibration means.

[0209] For example, the third fidelity gain of calibration means A is 12%, and the fourth fidelity gain is -3%; the third fidelity gain of calibration means B is 8%, and the fourth fidelity gain is 3%; the third fidelity gain of calibration means C is 7%, and the fourth fidelity gain is 1%. The third fidelity gains and fourth fidelity gains of the three calibration means are added together to obtain 9%, 11% and 8%, respectively. The calibration means B corresponding to 11% is used as the first calibration means.

[0210] By directly adding the third fidelity gain and the fourth fidelity gain, their influence on determining the first calibration means is made the same, thereby improving the fairness of determining the first calibration means.

[0211] The first calibration method is determined based on the third and fourth fidelity gains corresponding to each first candidate calibration method. Alternatively, different weights can be assigned to the third and fourth fidelity gains, and a weighted sum is calculated based on the weights. The first candidate calibration method with the largest weighted sum is selected as the first calibration method. The weights are set because, since the first candidate calibration method acts on the second qubit gate, the fidelity of the first qubit gate will be further calibrated later, and the fidelity change of the second qubit gate is more important in determining the first calibration method. Therefore, weights are used to bias the fidelity changes between the first and second qubit gates. For example, if the third fidelity gain has a weight of 0.7 and the fourth fidelity gain has a weight of 0.3, based on the above example, the weighted sum for calibration method A is 7.5%, the weighted sum for calibration method B is 6.5%, and the weighted sum for calibration method C is 5.2%. Therefore, calibration method A is selected as the first calibration method. Different weights can be set for the third fidelity gain and the fourth fidelity gain according to actual application requirements by using a weighted sum method, thereby improving the flexibility of determining the first calibration means.

[0212] In the embodiment of steps 1210 to 1230, the overall impact of each first candidate calibration means on the fidelity of the first quantum bit gate and the second quantum bit gate after calibrating the second quantum bit gate is comprehensively considered, and the first candidate calibration means that is most beneficial to the overall situation is used as the first calibration means, thereby improving the accuracy of determining the first calibration means.

[0213] In another embodiment, determining the first calibration means based on the second fidelity and the third fidelity corresponding to the first candidate calibration means includes:

[0214] sorting the first candidate calibration means based on the order of the second fidelity from high to low;

[0215] Starting with the first candidate calibration method in the ranking, the loop performs the following steps:

[0216] comparing the first fidelity with a third fidelity corresponding to the first candidate calibration means;

[0217] If the third fidelity is greater than or equal to the first fidelity, the loop is terminated and the corresponding first candidate calibration method is used as the first calibration method.

[0218] The specific process of this embodiment is shown in FIG13 , where x represents a calibration method. The first candidate calibration methods are sorted in descending order of second fidelity to obtain [x1, x2, x3, …]; k represents the first candidate calibration method in the current loop step, and the judgment starts with the first candidate calibration method in the sorting (corresponding to the highest second fidelity); F1 represents the first fidelity of the first qubit gate, and k.F3 represents the third fidelity corresponding to the first candidate calibration method represented by k. If the first fidelity is greater than the third fidelity, it means that after calibrating the second qubit gate using the first candidate calibration method represented by k, the fidelity of the first qubit gate is reduced. Even if this first candidate calibration method can achieve a good calibration effect for the fidelity of the second qubit gate, it is not the optimal choice. Therefore, the loop step is continued for the next first candidate calibration method in the sorting; if the first fidelity is less than or equal to the third fidelity, it means that after calibrating the second qubit gate using the first candidate calibration method represented by k, there will be no negative impact on the fidelity of the first qubit gate. Therefore, this first candidate calibration method can be used as the first calibration method.

[0219] For example, the first qubit gate has a first fidelity of 80%. Calibration method A has a second fidelity of 90% and a third fidelity of 78%. Calibration method B has a second fidelity of 86% and a third fidelity of 81%. Calibration method C has a second fidelity of 84% and a third fidelity of 83%. Sorting by second fidelity yields calibration method A, calibration method B, and calibration method C. Calibration method A has a third fidelity lower than the first fidelity, so calibration method B is selected as the first calibration method.

[0220] The advantage of this embodiment is that, under the premise of comprehensively considering the changes in the fidelity of the first qubit gate and the second qubit gate, there is no need to calculate the impact of each calibration means on the fidelity of the first qubit gate and the second qubit gate, which reduces the amount of calculation and improves the efficiency of determining the first calibration means.

[0221] The advantage of the embodiment of Figure 13 is that, when determining the first calibration means, not only the impact of the first candidate calibration means on the second quantum bit gate is considered, but also the impact on the first quantum bit gate is considered, thereby avoiding the problem that the fidelity of one quantum bit gate is improved while the fidelity of another quantum bit gate is reduced, ensuring the overall fidelity calibration effect of multiple quantum bit gates, and improving the efficiency of the overall fidelity calibration.

[0222] In the embodiment of steps 340-350, the second quantum bit gate is determined based on the first mapping relationship, and the first calibration means is determined based on the second mapping relationship. There is no need to traverse multiple quantum bit gates and a large number of calibration means, which improves the efficiency of determining the second quantum bit gate and the first calibration means.

[0223] As can be seen above, both the first and second mapping relationship sets are pre-stored sets. This allows the second qubit gate to be determined based on the first mapping relationship, and the first calibration method to be determined based on the second mapping relationship, eliminating the need to traverse multiple qubit gates and numerous calibration methods. This improves the efficiency of determining the second qubit gate and the first calibration method. The following describes how to determine the first and second mapping relationship sets.

[0224] A qubit gate performs a gate operation on the qubit by applying a radio frequency (RF) modulation signal to the qubit. Calibration of a qubit gate involves adjusting the RF modulation signal to bring the gate operation result close to the desired state. For a qubit, multiple qubit gates are correlated, and the fidelity of one qubit gate may affect the calibration of subsequent qubit gates. For example, calibrating gate H only achieves optimal calibration when the fidelity of gate X reaches 85%. Randomly selecting the qubit gate to be calibrated may result in poor calibration results, or even improve the fidelity of one qubit gate while reducing the fidelity of other qubit gates. Therefore, it is necessary to consider the correlation between qubit gates and determine the second qubit gate to be calibrated based on the fidelity of the first qubit gate.

[0225] The primary calibration method for calibrating the second qubit gate is also related to the primary fidelity of the first qubit gate. This is because calibration of other qubit gates is only effective when the primary fidelity of the first qubit gate reaches a predetermined standard. Randomly selecting a calibration method may result in a decrease in the fidelity of other qubit gates. In other words, the second qubit gate, determined based on the primary fidelity, and the primary calibration method used to calibrate the second qubit gate are both selected based on the primary fidelity to improve the overall qubit gate fidelity, and generally the option that maximizes the overall qubit gate fidelity improvement.

[0226] In some embodiments, determining the second qubit gate and the first calibration method based on the first fidelity can be accomplished by combining qubit gates other than the first qubit gate with multiple calibration methods, calibrating the qubit gates in the combination using the calibration methods in the combination, and obtaining the fidelity increments before and after calibration. The qubit gate in the combination with the largest fidelity increment is used as the second qubit gate, and the calibration method used in the combination is used as the first calibration method. For example, the qubit gates other than the first qubit gate include: gate X and gate Y, and the calibration methods include: calibration method A, calibration method B, and calibration method C. Then, after combining, the following result is obtained: (gate X, calibration method A), (gate X, calibration method B), (gate X, calibration method C), (gate Y, calibration method A), (gate Y, calibration method B), and (gate Y, calibration method C). Using calibration method A to calibrate gate X increases the fidelity from 75% to 90%, with a fidelity increment of 15%. Using calibration method B to calibrate gate X decreases the fidelity from 75% to 70%, with a fidelity increment of -5%, and so on. Obtain the fidelity increment before and after each combination calibration. If the fidelity increment obtained after calibrating gate X using calibration method A is the largest, then the second quantum gate is gate X and the first calibration method is calibration method A.

[0227] Due to the large number of qubit gate operations that must be performed on qubits, a wide variety of calibration methods are required, resulting in a large number of qubit gate and calibration method combinations. Testing each qubit gate individually and selecting the one with the best calibration results during qubit gate calibration is inefficient. Therefore, based on experiments, a first set of mapping relationships and a second set of mapping relationships can be predetermined, and the second qubit gate and the first calibration method can be determined based on the first fidelity.

[0228] In one embodiment, as shown in FIG14 , the first mapping relationship set and the second mapping relationship set are generated in the following manner:

[0229] Step 1410: Generate multiple data groups based on multiple qubit gates and multiple fidelity intervals, where a data group is generated by combining any qubit gate with any fidelity interval.

[0230] Step 1420: For each data group, obtain first fidelity gains corresponding to each of the plurality of qubit gates other than the qubit gate in the data group, where the first fidelity gains refer to fidelity gains after calibration of the plurality of qubit gates using the calibration methods selected by the respective qubit gates.

[0231] Step 1430: Determine, based on the first fidelity gain, a preferred qubit gate to be calibrated corresponding to each data group and a plurality of first candidate calibration methods used by the preferred qubit gate to be calibrated;

[0232] Step 1440: Generate a first mapping relationship set based on the correspondence between each data group and the preferred qubit gate to be calibrated, wherein each data group is a first element and the preferred qubit gate to be calibrated corresponding to each data group is a second element;

[0233] Step 1450: Generate a second mapping relationship set based on the correspondence between each data group and multiple first candidate calibration means, wherein each data group is a first element and multiple first candidate calibration means corresponding to each data group are second elements.

[0234] In step 1410, each of the multiple qubit gates is combined with each fidelity interval to generate multiple data sets. For example, if the qubit gates include Gate X and Gate Y, and the fidelity intervals include [85%, 90%), [90%, 95%), and [95%, 100%), then the generated data sets include (Gate X, [85%, 90%)), (Gate X, [90%, 95%)), (Gate X, [95%, 100%)), (Gate Y, [85%, 90%)), (Gate Y, [90%, 95%)), and (Gate Y, [95%, 100%)).

[0235] In step 1420, for each data group, a first fidelity gain corresponding to each of the plurality of qubit gates other than the qubit gate in the data group is obtained. The first fidelity gain refers to the difference between the sum of the fidelities of the plurality of qubit gates before and after calibration of the corresponding qubit gate. The corresponding qubit gate refers to each of the plurality of qubit gates other than the qubit gate in the data group. For each qubit gate, the difference between the sum of the fidelities of the plurality of qubit gates before and after calibration is obtained as the first fidelity gain.

[0236] Optionally, obtaining first fidelity gains corresponding to calibrated qubit gates other than the qubit gates in each data group includes:

[0237] Obtaining a first sum of the fidelities of the plurality of qubit gates before calibration of a third qubit gate in each data group, wherein the third qubit gate is any qubit gate among the plurality of qubit gates;

[0238] Obtaining a second sum of the fidelities of the plurality of qubit gates after the third qubit gate in each data group is calibrated using a third candidate calibration means;

[0239] A first fidelity gain of a third qubit gate in each data group is determined based on a first sum of the fidelities of the plurality of qubit gates and a second sum of the fidelities of the plurality of qubit gates.

[0240] For example, as shown in Figure 15 , qubit gates include: gate X, gate Y, and gate H. When determining the optimally calibrated qubit gate for a data set (gate X, [85%, 90%)), the first fidelity gains of gates Y and H are obtained. The first fidelity gain of gate Y refers to the difference between the second sum of the fidelities of gates X, Y, and H after calibration using a calibration method and the first sum of their fidelities before calibration. If, before calibration using a calibration method, the fidelities of gates X, Y, and H are 86%, 80%, and 81%, respectively, their sum is the first sum of the fidelities of gates X, Y, and H. After calibration using a calibration method, the fidelities of gates X, Y, and H are 84%, 83%, and 82%, respectively, and their sum is the second sum of the fidelities of gates X, Y, and H. The first fidelity gain of gate Y is then the value obtained by subtracting the first sum from the second sum, i.e., (84% + 83% + 82%) - (86% + 80% + 81%) = 2%. Similarly, the first fidelity gain of gate H is the difference between the second sum of the fidelity values ​​of gates X, Y, and H after calibration using a calibration method and the first sum of the fidelity values ​​before calibration.

[0241] Optionally, obtaining a first sum of the fidelities of the plurality of qubit gates before calibration of the third qubit gate in each data group includes:

[0242] A first sum of the fidelities of the plurality of qubit gates before calibration of the third qubit gate in each data group is calculated based on the weights of the plurality of qubit gates.

[0243] Optionally, obtaining a second sum of the fidelities of the plurality of qubit gates after the third qubit gate in each data group is calibrated using a third candidate calibration means includes:

[0244] A first sum of the fidelities of the plurality of qubit gates and a second sum of the fidelities of the plurality of qubit gates are calculated based on the weights of the plurality of qubit gates.

[0245] For example, as shown in Figure 15, the qubit gates include: gate X, gate Y, and gate H. The weight corresponding to gate X is 0.3, the weight corresponding to gate Y is 0.5, and the weight corresponding to gate H is 0.2. If, before calibration of gate Y using a certain calibration method, the fidelity of gates X, Y, and H is 86%, 80%, and 81%, respectively, the first sum of the fidelity of gates X, Y, and H is the sum of the weight corresponding to each gate multiplied by the fidelity of each gate. For example, 0.3*86%+0.5*80%+0.2*81%=82.9%

[0246] After calibration using a certain calibration method, the fidelities of the three are 84%, 83%, and 82%, respectively. The second sum of the fidelities of gates X, Y, and H is the sum of the weight corresponding to each gate multiplied by the fidelity of each gate. For example, 0.3*84%+0.5*83%+0.2*82%=83.1%.

[0247] When calibrating gates Y and H, multiple different calibration methods can be selected. For example, the calibration methods include calibration method A, calibration method B, calibration method C, and calibration method D. Gate Y can be calibrated using calibration method A, calibration method B, calibration method C, and calibration method D, respectively, to obtain the first fidelity gain of gate Y after calibration using the different calibration methods.

[0248] Then, the gate H is calibrated using calibration means A, calibration means B, calibration means C, and calibration means D respectively to obtain the first fidelity gain of the gate H after calibration using different calibration means.

[0249] Then, based on the first fidelity gain of gate Y after calibration using different calibration means and the first fidelity gain of gate H after calibration using different calibration means, the preferred calibrated quantum bit gate corresponding to the data group (gate X, [85%, 90%)) and the first candidate calibration means for calibrating the preferred calibrated quantum bit gate are determined.

[0250] Taking FIG15 as an example, when determining the optimal calibrated qubit gate for the data set (gate X, [85%, 90%)), the specific operations are as follows:

[0251] Before using a calibration method to calibrate other qubit gates, the fidelity of gates X, Y, and H were 86%, 80%, and 81%, respectively.

[0252] After calibration method A is used to calibrate gate Y, the fidelity of the three is 84%, 83%, and 82%, respectively. Therefore, the first fidelity gain of gate Y using calibration method A is (84% + 83% + 82%) - (86% + 80% + 81%) = 2%;

[0253] After calibration method B is used to calibrate gate Y, the fidelity of the three is 85%, 84%, and 81%, respectively. Therefore, the first fidelity gain of gate Y using calibration method A is (85% + 84% + 81%) - (86% + 80% + 81%) = 3%;

[0254] After calibration of gate H using calibration method A, the fidelity of the three gates is 83%, 82%, and 82%, respectively. Then the first fidelity gain of gate Y using calibration method A is (83% + 82% + 82%) - (86% + 80% + 81%) = 0%;

[0255] After calibration of gate H using calibration method B, the fidelity of the three gates is 82%, 84%, and 82%, respectively. Then the first fidelity gain of gate Y using calibration method A is (82%+84%+82%)-(86%+80%+81%)=1%.

[0256] It can be seen that after using calibration means B to calibrate gate Y, the first fidelity gain is the largest. Therefore, the quantum bit gate Y with the largest first fidelity gain is selected as the preferred calibrated quantum bit gate corresponding to the data group (gate X, [85%, 90%)), and calibration means B is selected as the first candidate calibration means.

[0257] Calibrating the fidelity of one qubit gate affects the fidelity of other qubit gates. Even if the fidelity of the calibrated qubit gate increases significantly before and after calibration, the fidelity of other qubit gates may decrease. Therefore, by taking the difference between the sum of the fidelities of multiple qubit gates before and after calibration as the first fidelity gain, we can find the optimal calibrated qubit gate from among multiple qubit gates for the best overall calibration effect.

[0258] After obtaining the first fidelity gain corresponding to each qubit gate other than the qubit gates in the data set, the preferred qubit gate to be calibrated for the data set is determined based on the first fidelity gains of the multiple qubit gates. The higher the first fidelity gain corresponding to the qubit gate, the greater the overall fidelity improvement effect will be achieved by calibrating this qubit gate based on the data set. Therefore, the qubit gate with the highest first fidelity gain can be used as the preferred qubit gate to be calibrated for the data set, generating a first mapping relationship between the data set and the preferred qubit gate to be calibrated. The calibration method with the highest first fidelity gain is used as the calibration method for calibrating the preferred qubit gate to be calibrated for the data set, generating a first mapping relationship between the data set and the first candidate calibration method.

[0259] In step 1430, based on the first fidelity gain, determining a preferred qubit gate to be calibrated corresponding to each data group and a plurality of first candidate calibration methods used by the preferred qubit gate to be calibrated, including:

[0260] When the first fidelity gain of the third quantum bit gate after calibration using the third candidate calibration means is greater than the gain threshold, the third quantum bit gate is determined to be the preferred quantum bit gate to be calibrated corresponding to the data group, and the third candidate calibration means is determined to be the candidate calibration means corresponding to the data group.

[0261] Specifically, determining the preferred qubit gate to be calibrated and the candidate calibration method from among multiple qubit gates and multiple calibration methods can be done by setting a gain threshold. If the first fidelity gain after calibrating a qubit gate using a certain calibration method is greater than or equal to the gain threshold, the qubit gate is selected as the preferred qubit gate to be calibrated, and the calibration method is selected as a candidate calibration method. For example, if the gain threshold is 2%, then based on the above example, calibration methods A and B calibrate gate Y to achieve first fidelity gains of 3% and 2%, respectively, which meet the gain threshold. Calibration methods A and B calibrate gate H to achieve first fidelity gains of 0% and 1%, respectively, which do not meet the gain threshold. Therefore, gate Y is determined to be the preferred qubit gate to be calibrated for the data set (gate X, [85%, 90%)), and calibration methods A and B can be selected as candidate calibration methods for the data set (gate X, [85%, 90%)). By using the gain threshold to determine the preferred qubit gate to be calibrated and the candidate calibration means, it can be ensured that each candidate calibration means can bring a relatively good calibration effect for the qubit gate to be calibrated corresponding to the data group.

[0262] In another embodiment, when determining a preferred qubit gate to be calibrated and a candidate calibration means from among multiple qubit gates and multiple calibration means, the number of candidate calibration means can be set, and the multiple candidate calibration means can be sorted according to the first fidelity gain, with the top candidate calibration means being selected as the candidate calibration means. For example, if the number of candidate calibration means is 2, then according to the above example, calibration means A and calibration means B can be selected as candidate calibration means for the data set (gate X, [85%, 90%)). Through this embodiment, if the first fidelity gain corresponding to many calibration means exceeds the gain threshold, a small number of calibration means with higher first fidelity gain can be selected from them, so that the first calibration means can be determined from the small number of calibration means with higher first fidelity gain, which helps to improve the efficiency of determining the first calibration means.

[0263] When generating the second mapping relationship between the data group and the candidate calibration means, the data group and the candidate calibration means may be directly generated in correspondence, such as the generation result shown in Table 5.

[0264] Table 5 Second mapping relationship between data groups and candidate calibration methods

[0265] In some embodiments, the calibration weight of each candidate calibration means can also be determined based on the first fidelity gain of the candidate calibration means, and a second mapping relationship is generated by corresponding the data group to the calibration weight of the candidate calibration means. The calibration weight indicates the calibration amplitude of the candidate calibration means for the quantum bit gate to be calibrated corresponding to the data group. Here, the calibration amplitude can be specifically understood as the fidelity gain obtained by calibration. The larger the calibration amplitude, the larger the calibration weight value. For example, the first fidelity gain of calibration means B is 7%, and the first fidelity gain of calibration means D is 12%. Then the calibration weight of calibration means B is 7% / (7%+12%)=0.37, and the calibration weight of calibration means D is 12% / (7%+12%)=0.63. At this time, the result of generating the second mapping relationship between the candidate calibration means and the candidate calibration means is shown in Table 6.

[0266] Table 6 Second mapping relationship between data groups and candidate calibration methods

[0267] An advantage of recording the calibration weight in the second mapping relationship is that when determining the first calibration means, it can be determined directly according to the weight, thereby improving the efficiency of determining the first calibration means.

[0268] The process of generating the first and second mapping relationship sets in steps 1410-1450 involves determining the qubit gates for each data group and candidate calibration methods for each data group based on the calibration effect of the overall multi-qubit gates, and generating a first mapping relationship set between the data group and the preferred calibrated qubit gates, and a second mapping relationship set between the data group and the candidate calibration methods. This ensures that after the second qubit gate is obtained based on the first mapping relationship set and the first calibration method is obtained based on the first mapping relationship set, the calibration process for the fidelity of the second qubit gate is beneficial to the fidelity of the overall multi-qubit gates.

[0269] Detailed description of step 360

[0270] In step 360, the second qubit gate is calibrated using the first calibration means, which essentially uses the first calibration means to adjust the radio frequency signal of the qubit so that the gate operation based on the second qubit gate on the qubit can make the state of the qubit as close to the desired state as possible.

[0271] The embodiment of steps 310-360 only details the process of calibrating one of the multiple qubit gates of a qubit. In practice, multiple qubit gates can be calibrated. Therefore, the embodiment of steps 310-360 can be used as the starting process for calibrating multiple qubit gates. In one embodiment, as shown in FIG16 , after step 360, the following is further included:

[0272] Step 1610: Determine the second qubit gate as the current qubit gate, and loop through the following steps:

[0273] Step 1620: Perform fidelity testing on multiple qubit gates.

[0274] Step 1630: When it is detected that the fidelity of a qubit gate among the multiple qubit gates is less than a predetermined fidelity value, determine the qubit gate to be calibrated and a calibration method for calibrating the qubit gate to be calibrated based on the fidelity of the current qubit gate, calibrate the qubit gate to be calibrated based on the calibration method, and update the current qubit gate based on the qubit gate to be calibrated.

[0275] Step 1640: When the fidelity of the plurality of quantum bit gates is greater than or equal to the predetermined fidelity value, the loop step is terminated.

[0276] In this embodiment, after the second qubit gate is calibrated, the second qubit gate is used as the current qubit gate, and a loop step is entered: fidelity detection is performed on multiple qubit gates; if there is a qubit gate among the multiple qubit gates whose fidelity is less than a predetermined fidelity value, then the qubit gate to be calibrated and the calibration means for calibrating the qubit gate to be calibrated are determined according to the fidelity of the current qubit gate. The specific process is the same as determining the second qubit gate and the first calibration means according to the first fidelity in steps 340 and 350, and will not be repeated here; the qubit gate to be calibrated is calibrated based on the calibration means, and the qubit gate to be calibrated is used as the current qubit gate, and the loop step is executed again; if the fidelity of multiple qubit gates is greater than the predetermined fidelity value, it means that multiple qubit gates have met the calibration requirements, and the loop step is terminated.

[0277] The predetermined fidelity value is the threshold at which the fidelity of the quantum bit gate reaches the calibration requirements. When the fidelity of the quantum bit gate is greater than or equal to the predetermined fidelity value, the quantum bit can be used to perform quantum computing tasks.

[0278] The process of calibrating multiple qubit gates of a qubit is exemplarily described below with reference to FIG. 17 .

[0279] For example, the quantum bit gates corresponding to the quantum bit include: Gate I, Gate X, Gate Y and Gate M, with initial fidelity of 75%, 77%, 81% and 78% respectively.

[0280] In step 1710, the initial quantum bit gate with the highest fidelity is used as the first quantum bit gate, so the first quantum bit gate is gate Y.

[0281] In step 1711, a gate operation of gate Y is performed on the quantum bit, and the first fidelity of the first quantum bit gate is determined to be 81% based on the difference between the actual result of the operation and the expected result.

[0282] In step 1712, it is determined that the first fidelity range in which the first fidelity is located is [80%, 85%).

[0283] In step 1713, a first mapping relationship table is obtained, and according to the first qubit gate and the first fidelity interval, the second qubit gate to be calibrated is searched in the first mapping relationship table as gate X.

[0284] In step 1714, a second mapping relationship table is obtained, and according to the first quantum bit gate and the first fidelity interval, multiple first candidate calibration means are found in the second mapping relationship table, namely, calibration means D, calibration means F, and calibration means G.

[0285] In step 1715, the second fidelity corresponding to each first candidate calibration means is obtained. The second fidelity corresponding to calibration means D is 86%, the second fidelity corresponding to calibration means F is 97%, and the second fidelity corresponding to calibration means G is 95%.

[0286] In step 1716, after the second quantum bit gate is calibrated based on each first candidate calibration means, the third fidelity corresponding to the first quantum bit gate is: the third fidelity corresponding to calibration means D is 81%, the third fidelity corresponding to calibration means F is 80%; the third fidelity corresponding to calibration means G is 82%.

[0287] In step 1717, based on the second fidelity and the third fidelity corresponding to each first candidate calibration means, a first calibration means is determined from the plurality of first candidate calibration means, and the first calibration means is calibration means G;

[0288] In step 1718, the gate X is calibrated using calibration means G.

[0289] In step 1719, gate X is determined to be the current qubit gate.

[0290] Enter step 1720 for the first time and perform fidelity detection on all qubit gates. The fidelities of gates I, X, Y, and M are 75%, 95%, 81%, and 78%, respectively. The predetermined fidelity value is 95%. If there is a qubit gate with a fidelity less than the predetermined fidelity value, enter step 1721.

[0291] In step 17621, based on the fidelity of gate X (95%), the qubit gate to be calibrated is determined to be gate I, the calibration method applied is calibration method C, gate I is calibrated using calibration method C, and gate I is used as the current qubit gate, and step 1720 is entered.

[0292] Enter step 1720 for the second time and perform fidelity detection on all qubit gates. The fidelities of gates I, X, Y, and M are 96%, 95%, 81%, and 78%, respectively. If there is a qubit gate with a fidelity less than the predetermined fidelity value, enter step 1721.

[0293] In step 1721, based on the fidelity of gate I (96%), it is determined that the quantum bit gate to be calibrated is gate M, the calibration means applied is calibration means K, and gate M is calibrated using calibration means K. Gate M is used as the current quantum bit gate, and step 1720 is entered.

[0294] Enter step 1720 for the third time and perform fidelity detection on all qubit gates. The fidelities of gates I, X, Y, and M are 96%, 95%, 81%, and 95%, respectively. If there is a qubit gate with a fidelity less than the predetermined fidelity value, enter step 1721.

[0295] In step 1721, based on the fidelity of gate M (95%), the quantum bit gate to be calibrated is determined to be gate Y, the calibration means applied is calibration means S, gate Y is calibrated using calibration means S, and gate Y is used as the current quantum bit gate, and step 1720 is entered.

[0296] Enter step 1720 for the fourth time, and perform fidelity detection on all qubit gates. The fidelity corresponding to gate I, gate X, gate Y and gate M are 96%, 95%, 97% and 95% respectively. There is no qubit gate with a fidelity less than the predetermined fidelity value, so enter step 1722.

[0297] In step 1722, the loop step is terminated to complete the calibration of multiple quantum bit gates of the quantum bit.

[0298] Description of the apparatus and device of the present disclosure

[0299] 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 an object, such as object attribute information or attribute information sets, the permission or consent of the object will be obtained first, and the collection, use and processing of such data will comply with the relevant laws, regulations and standards of the relevant countries and regions. In addition, when the embodiment of the present application needs to obtain object attribute information, the object's separate permission or separate consent will be obtained through a pop-up window or by jumping to a confirmation page. After clearly obtaining the object's separate permission or separate consent, the necessary object-related data for the normal operation of the embodiment of the present application will be obtained.

[0300] 18 , which is a schematic diagram of a structure of a qubit gate fidelity calibration device 2000 according to an embodiment of the present disclosure. The qubit gate fidelity calibration device 2000 includes:

[0301] A first determining unit 2010 is configured to determine a first qubit gate from a plurality of qubit gates for processing qubits;

[0302] A first obtaining unit 2020 is configured to obtain a first fidelity of a first qubit gate;

[0303] A second determining unit 2030 is configured to determine a first fidelity interval in which the first fidelity is located from a plurality of preset fidelity intervals;

[0304] The second determining unit 2030 is further configured to determine, from the plurality of qubit gates, a second qubit gate to be calibrated based on the first qubit gate and the first fidelity interval and based on a pre-stored first mapping relationship set, wherein the first mapping relationship set includes first mapping relationships between a plurality of first elements and a plurality of second elements, the first elements including a plurality of previously calibrated qubit gates and the fidelity intervals within which their fidelities lie, and the second elements including a preferred qubit gate to be calibrated;

[0305] The second determining unit 2030 is further configured to determine, according to the first qubit gate and the first fidelity interval, a first calibration means from a plurality of first candidate calibration means based on a pre-stored second mapping relationship set, the second mapping relationship set comprising second mapping relationships between a plurality of first elements and a plurality of third elements, the third elements comprising the plurality of calibration means;

[0306] The calibration unit 2040 is configured to calibrate the second quantum bit gate based on the first calibration method.

[0307] Optionally, the second determining unit 2030 is specifically configured to:

[0308] Obtaining a second fidelity corresponding to each first candidate calibration means, where the second fidelity is a fidelity obtained by calibrating the second qubit gate based on each first candidate calibration means;

[0309] A first calibration method is determined from a plurality of first candidate calibration methods based on the second fidelity corresponding to each first candidate calibration method.

[0310] Optionally, the second determining unit 2030 is specifically configured to:

[0311] Obtaining a third fidelity corresponding to the first qubit gate after calibrating the second qubit gate based on each first candidate calibration means;

[0312] A first calibration method is determined from a plurality of first candidate calibration methods based on the second fidelity and the third fidelity corresponding to each first candidate calibration method.

[0313] Optionally, the calibration means calibrates the fidelity of the qubit gate by adjusting one or more of the amplitude, frequency and phase of the qubit's radio frequency signal;

[0314] The second determining unit 2030 is specifically configured to:

[0315] Calculating the average of the amplitudes corresponding to the plurality of first candidate calibration means to obtain a first amplitude average, calculating the average of the frequencies corresponding to the plurality of first candidate calibration means to obtain a first frequency average, and calculating the average of the phases corresponding to the plurality of first candidate calibration means to obtain a first phase average;

[0316] determining a second candidate calibration means according to the first amplitude mean, the first frequency mean, and the first phase mean;

[0317] A first calibration means is determined from a calibration means set consisting of a plurality of first candidate calibration means and a second candidate calibration means.

[0318] Optionally, the second determining unit 2030 is further configured to:

[0319] Generate the first mapping relationship set and the second mapping relationship set:

[0320] Generating a plurality of data groups based on a plurality of qubit gates and a plurality of fidelity intervals, wherein the data groups are generated by combining any qubit gate with any fidelity interval;

[0321] For each data group, obtaining first fidelity gains corresponding to qubit gates other than the qubit gates in each data group after calibration, wherein the first fidelity gains refer to fidelity gains of the qubit gates other than the qubit gates in each data group after calibration using the selected calibration method;

[0322] Determining, according to the first fidelity gain, a preferred qubit gate to be calibrated corresponding to each data group and a plurality of first candidate calibration means adopted by the preferred qubit gate to be calibrated;

[0323] Generate the first mapping relationship set according to the corresponding relationship between each data group and the qubit gate preferably to be calibrated;

[0324] A second mapping relationship set is generated according to the correspondence between each data group and a plurality of first candidate calibration means.

[0325] Optionally, the second determining unit 2030 is further configured to:

[0326] Obtaining a first sum of the fidelities of the plurality of qubit gates before calibration of a third qubit gate in each data group, wherein the third qubit gate is any qubit gate among the plurality of qubit gates;

[0327] Obtaining a second sum of the fidelities of the plurality of qubit gates after the third qubit gate in each data group is calibrated using a third candidate calibration means;

[0328] A first fidelity gain of a third qubit gate in each data group is determined based on a first sum of the fidelities of the plurality of qubit gates and a second sum of the fidelities of the plurality of qubit gates.

[0329] Optionally, the second determining unit 2030 is further configured to:

[0330] When the first fidelity gain of the third quantum bit gate after calibration using the third candidate calibration means is greater than the gain threshold, the third quantum bit gate is determined to be the preferred quantum bit gate to be calibrated corresponding to the data group, and the third candidate calibration means is determined to be the candidate calibration means corresponding to the data group.

[0331] Optionally, the first qubit gate is a qubit gate that has been calibrated before the second qubit gate, and after the first qubit gate is calibrated, no other qubit gates in the multiple qubit gates have been calibrated.

[0332] Optionally, the qubit gate fidelity calibration device 2000 further includes:

[0333] A cyclic calibration unit (not shown) is used to determine that the second qubit gate is the current qubit gate and cyclically perform the following steps:

[0334] Fidelity testing of multiple qubit gates;

[0335] When it is detected that the fidelity of a qubit gate among the multiple qubit gates is less than a predetermined fidelity value, determining a qubit gate to be calibrated and a calibration means for calibrating the qubit gate to be calibrated according to the fidelity of the current qubit gate, calibrating the qubit gate to be calibrated based on the calibration means, and updating the current qubit gate based on the qubit gate to be calibrated;

[0336] When the fidelity of the plurality of quantum bit gates is greater than or equal to a predetermined fidelity value, the loop step is terminated.

[0337] Optionally, the first acquiring unit 2020 includes:

[0338] Performing the operation corresponding to the first qubit gate on the qubit and obtaining the actual state of the qubit;

[0339] A first fidelity of the first qubit gate is determined based on a difference between the actual state and the desired state.

[0340] Optionally, the first determining unit 2010 includes:

[0341] Obtaining an initial fidelity value of each qubit gate in a plurality of qubit gates of a qubit;

[0342] The qubit gate with the highest initial fidelity value is determined to be the first qubit gate.

[0343] FIG19 is a block diagram of a portion of a computer 140 that implements the qubit gate fidelity calibration method according to an embodiment of the present disclosure. Computer 140 may vary significantly due to configuration or performance differences and may include one or more central processing units (CPUs) 2122 (e.g., one or more processors) and memory 2132, and one or more storage media 2130 (e.g., one or more mass storage devices) storing application programs 2142 or data 2144. The memory 2132 and storage media 2130 may be either transient or persistent storage. The program stored in storage media 2130 may include one or more modules (not shown), each of which may include a series of instruction operations on computer 140. Furthermore, CPU 2122 may be configured to communicate with storage media 2130, executing the series of instruction operations on storage media 2130 on computer 140.

[0344] The computer 140 may also include one or more power supplies 2126, one or more wired or wireless network interfaces 2150, one or more input and output interfaces 2158, and / or one or more operating systems 2141, such as Windows Server™, Mac OS X™, Unix™, Linux™, FreeBSD™, etc.

[0345] The processor in the computer 140 can be used to execute the qubit gate fidelity calibration method of the embodiment of the present disclosure.

[0346] The embodiments of the present disclosure also provide a computer-readable storage medium, which is used to store program code, and the program code is used to execute the quantum bit gate fidelity calibration method of each of the aforementioned embodiments.

[0347] The present disclosure also provides a computer program product, which includes a computer program. A processor of a computer device reads and executes the computer program, so that the computer device implements the above-mentioned method for calibrating the fidelity of a quantum bit gate.

[0348] The terms "first," "second," "third," "fourth," and the like (if any) in the specification of the present disclosure and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present disclosure described herein, for example, can be implemented in orders other than those illustrated or described herein. In addition, the terms "comprises" and "comprising," and any variations thereof, are intended to cover non-exclusive inclusions, e.g., a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus.

[0349] It should be understood that in the present disclosure, "at least one (item)" refers to one or more, and "plurality" refers to 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.

[0350] It should be understood that in the description of the embodiments of the present disclosure, the meaning of multiple (or multiple items) is 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.

[0351] In the several embodiments provided in the present disclosure, 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 interfaces, devices or units, which can be electrical, mechanical or other forms.

[0352] 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.

[0353] In addition, the functional units in the various embodiments of the present disclosure 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 hardware or software functional units.

[0354] 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 disclosure is essentially 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, and the computer software product is stored in a storage medium, including a number of 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 disclosure. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program code.

[0355] It should also be understood that the various implementations provided in the embodiments of the present disclosure can be combined arbitrarily to achieve different technical effects.

[0356] The above is a specific description of the implementation methods of the present disclosure, but the present disclosure is not limited to the above implementation methods. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present disclosure. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present disclosure.

Claims

1. A method for calibrating a quantum bit gate, characterized in that: include: determining a first qubit gate from a plurality of qubit gates for processing a qubit; Obtaining a first fidelity of the first quantum bit gate; Determining a first fidelity interval in which the first fidelity is located from a plurality of preset fidelity intervals; According to the first qubit gate and the first fidelity interval, a second qubit gate to be calibrated is determined from the plurality of qubit gates based on a pre-stored first mapping relationship set, wherein the first mapping relationship set includes a first mapping relationship between a plurality of first elements and a plurality of second elements, the first elements include a plurality of previously calibrated qubit gates and the fidelity intervals in which their fidelities are located, and the second elements include a qubit gate preferably to be calibrated; Determining a first calibration means from a plurality of first candidate calibration means based on a pre-stored second mapping relationship set according to the first qubit gate and the first fidelity interval, the second mapping relationship set comprising second mapping relationships between a plurality of the first elements and a plurality of third elements, the third element comprising the plurality of calibration means; The second quantum bit gate is calibrated using the first calibration means.

2. The calibration method according to claim 1, characterized in that: The step of determining the first calibration means from a plurality of first candidate calibration means comprises: Obtaining a second fidelity corresponding to the second qubit gate after the second qubit gate is calibrated by each of the first candidate calibration means; The first calibration approach is determined from among the plurality of first candidate calibration approaches based on the plurality of the second fidelities.

3. The calibration method according to claim 2, characterized in that: After obtaining the second fidelity corresponding to each of the first candidate calibration means, the method further includes: Obtaining a third fidelity corresponding to the first qubit gate after calibrating the second qubit gate based on each of the first candidate calibration means; The determining the first calibration means from the plurality of first candidate calibration means based on the plurality of second fidelities comprises: The first calibration means is determined from among the plurality of first candidate calibration means based on the plurality of second fidelities and the plurality of third fidelities.

4. The calibration method according to claim 1, characterized in that: The calibration means calibrates the fidelity of the quantum bit gate by adjusting one or more of the amplitude, frequency and phase of the radio frequency signal of the quantum bit; After searching and obtaining a plurality of first candidate calibration means in the second mapping relationship table based on the first quantum bit gate and the first fidelity interval, the method further includes: The determining, according to the first qubit gate and the first fidelity interval, a first calibration means from a plurality of first candidate calibration means based on a pre-stored second mapping relationship set, comprises: Determine a plurality of first candidate calibration means according to the first qubit gate and the first fidelity interval and based on a pre-stored second mapping relationship set; Calculating the average values ​​of the amplitudes corresponding to the plurality of first candidate calibration means to obtain a first amplitude average value, calculating the average values ​​of the frequencies corresponding to the plurality of first candidate calibration means to obtain a first frequency average value, and calculating the average values ​​of the phases corresponding to the plurality of first candidate calibration means to obtain a first phase average value; Determine a second candidate calibration means according to the first amplitude mean, the first frequency mean, and the first phase mean; The first calibration means is determined from a calibration means set consisting of the plurality of first candidate calibration means and the second candidate calibration means.

5. The calibration method according to any one of claims 1 to 4, characterized in that: The first mapping relationship set and the second mapping relationship set are generated in the following manner: Generate multiple data groups based on multiple quantum bit gates and multiple fidelity intervals, wherein the data groups are generated by combining any quantum bit gate with any fidelity interval; For each data group, obtaining first fidelity gains corresponding to qubit gates other than the qubit gates in each data group after calibration, wherein the first fidelity gain refers to the fidelity gain of the qubit gates other than the qubit gates in each data group after calibration using the calibration means selected by the qubit gates; Determining, according to the first fidelity gain, a preferred qubit gate to be calibrated corresponding to each data group and a plurality of first candidate calibration means adopted by the preferred qubit gate to be calibrated; Generate the first mapping relationship set according to the corresponding relationship between each data group and the quantum bit gate preferably to be calibrated; A second mapping relationship set is generated according to the correspondence between each data group and a plurality of first candidate calibration means.

6. The method according to claim 5, characterized in that The obtaining of first fidelity gains corresponding to the calibrated qubit gates other than the qubit gates in each data group includes: Obtaining a first sum of the fidelity of the plurality of qubit gates before calibration of a third qubit gate in each data group, wherein the third qubit gate is any qubit gate among the plurality of qubit gates; Obtaining a second sum of the fidelities of the plurality of qubit gates after the third qubit gate in each data group is calibrated using a third candidate calibration means; A first fidelity gain of a third qubit gate in each of the data groups is determined based on a first sum of the fidelities of the plurality of qubit gates and a second sum of the fidelities of the plurality of qubit gates.

7. The method according to claim 6, characterized in that Determining, according to the first fidelity gain, a preferred qubit gate to be calibrated corresponding to each data group and a plurality of candidate calibration means adopted by the preferred qubit gate to be calibrated, comprising: When the first fidelity gain of the third qubit gate calibrated by the third candidate calibration means is greater than the gain threshold, the third qubit gate is determined to be the preferred qubit gate to be calibrated corresponding to the data group. An accurate quantum bit gate is used to determine the third candidate calibration means as the candidate calibration means corresponding to the data group.

8. The method according to any one of claims 1 to 7, characterized in that The first qubit gate is a qubit gate that has been calibrated before the second qubit gate, and after the first qubit gate has been calibrated, other qubit gates among the multiple qubit gates have not been calibrated.

9. The calibration method according to any one of claims 1 to 8, characterized in that: After the first calibration means is used to calibrate the second quantum bit gate, the method further includes: Determine that the second qubit gate is the current qubit gate, and loop through the following steps: Performing fidelity testing on the plurality of quantum bit gates; When it is detected that the fidelity of a qubit gate among the multiple qubit gates is less than a predetermined fidelity value, determining a qubit gate to be calibrated and a calibration means for calibrating the qubit gate to be calibrated according to the fidelity of the current qubit gate, calibrating the qubit gate to be calibrated based on the calibration means, and updating the current qubit gate based on the qubit gate to be calibrated; When the fidelity of the plurality of quantum bit gates is greater than or equal to a predetermined fidelity value, the loop step is terminated.

10. The calibration method according to any one of claims 1 to 9, characterized in that: Obtaining a first fidelity of the first quantum bit gate includes: Performing an operation corresponding to the first quantum bit gate on the quantum bit, and obtaining an actual state of the quantum bit; The first fidelity of the first qubit gate is determined based on a difference between the actual state and the expected state.

11. The calibration method according to any one of claims 1 to 10, characterized in that: The step of determining a first qubit gate from a plurality of qubit gates corresponding to the qubit includes: Obtaining an initial fidelity value of each qubit gate in a plurality of qubit gates of the qubit; The quantum bit gate with the highest initial fidelity value is determined to be the first quantum bit gate.

12. A device for calibrating the fidelity of a quantum bit gate, characterized in that: include: A first determining unit, configured to determine a first qubit gate from a plurality of qubit gates for processing qubits; A first acquisition unit, configured to acquire a first fidelity of the first quantum bit gate; a second determining unit, configured to determine a first fidelity interval in which the first fidelity is located from a plurality of preset fidelity intervals; The second determination unit is further used to determine a second qubit gate to be calibrated from the plurality of qubit gates based on a pre-stored first mapping relationship set according to the first qubit gate and the first fidelity interval, the first mapping relationship set comprising a first mapping relationship between a plurality of first elements and a plurality of second elements, the first element comprising a plurality of previously calibrated qubit gates and the fidelity intervals in which their fidelities are located, and the second element comprising a qubit gate preferably to be calibrated; The second determination unit is further configured to determine a first calibration means from a plurality of first candidate calibration means based on a pre-stored second mapping relationship set according to the first qubit gate and the first fidelity interval, the second mapping relationship set comprising second mapping relationships between a plurality of the first elements and a plurality of third elements, the third element comprising the plurality of calibration means; A calibration unit is used to calibrate the second quantum bit gate using the first calibration means.

13. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the method for calibrating the fidelity of the quantum bit gate described in any one of claims 1 to 11 is implemented.

14. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for calibrating the fidelity of a quantum bit gate as described in any one of claims 1 to 11 is implemented.

15. A computer program product, comprising a computer program, wherein the computer program is read and executed by a processor of a computer device, so that the computer device executes the method for calibrating the fidelity of a quantum bit gate as described in any one of claims 1 to 11.

Images