Quantum chip control method and device and quantum computer

Abstract

The invention discloses a quantum chip control method and device, and a quantum computer, the working frequency of a second adjustable coupler is adjusted in a first preset range, and the frequency of a second quantum bit is affected when the working frequency of the second adjustable coupler is adjusted, so that the quantum chip is controlled. It can be understood that the frequency of the second quantum bit can be corrected by adjusting the working frequency of the second adjustable coupler, so that the quantum state leakage phenomenon is inhibited. According to the scheme, the problem of quantum state leakage of a quantum chip in the prior art is effectively solved, and the accuracy of execution results of a quantum computer is improved to a certain extent.

Description

Technical Field

[0001] The present invention relates to the field of quantum computing technology, and in particular to a control method and device for a quantum chip and a quantum computer. Background Art

[0002] Quantum computing and quantum information is an interdisciplinary subject based on the principles of quantum mechanics to achieve computing and information processing tasks. It has a very close connection with quantum physics, computer science, informatics and other disciplines, and has developed rapidly in the past two decades. Quantum algorithms based on quantum computers in scenarios such as factorization and unstructured search have shown performance far beyond the existing algorithms based on classical computers, and this direction has also been expected to exceed existing computing capabilities. Since quantum computing has the potential to far exceed the performance of classical computers in solving specific problems, in order to realize a quantum computer, it is necessary to obtain a quantum chip that contains a sufficient number and quality of quantum bits, and can perform quantum logic gate operations and read quantum bits with extremely high fidelity.

[0003] The quantum chip is to the quantum computer what the CPU is to the traditional computer. The quantum chip is the core component of the quantum computer. The quantum chip is the processor that performs quantum computing. The quantum chip integrates multiple one-to-one and mutually coupled quantum bits and reading cavities. Each quantum chip needs to be tested and characterized before it is officially put into use. The quantum computer also includes a measurement and control system that provides a measurement and control environment for the quantum chip. The measurement and control system mainly includes hardware equipment located in the room temperature layer and low-temperature devices and signal transmission lines located in the dilution refrigerator. After the quantum chip is packaged, it is fixed in the extremely low temperature layer of the bottom layer of the dilution refrigerator, and is finally connected to the hardware equipment at room temperature through the coaxial line between the layers. In this measurement and control system, when regulating the quantum state of the quantum bit, two types of lines are mainly used, one is the first type of transmission line (also known as the quantum state control line) used to drive the quantum state of the quantum bit, and the other is the second type of transmission line (also known as the frequency control line) used to regulate the frequency of the quantum bit.

[0004] In the quantum bit expansion architecture based on adjustable couplers, two quantum bits can be coupled through a fixed capacitive coupling and an adjustable coupler with adjustable coupling coefficient. The structure of the adjustable coupler is similar to that of the quantum bit, except that the adjustable coupler does not have a quantum state control line and a resonant cavity that can directly read information. In order to avoid problems such as resonance caused by the small frequency difference between adjacent quantum bits and adjustable couplers, the frequency of the adjustable coupler is generally set higher when allocating the operating frequencies of the quantum bits and adjustable couplers to reduce the frequency difference between the two. Figure 1 Take the quantum chip shown in as an example, where Q0, Q1, Q2, Q3, Q5, Q6 are quantum bits, C01 , C 12 , C 23 , C 03 , C 15 , C 56 , C 26 The operating frequency of the adjustable coupler can be set within the range of 6-8GHz, and the operating frequency of the quantum bit can be set within the range of 4-5GHz. In addition, the frequency between two adjacent quantum bits also presents high and low frequency changes. For example, if quantum bit Q0 is set as a high-frequency bit, then quantum bit Q1 is set as a low-frequency bit, and quantum bits Q2 and quantum bits Q5 need to be set as high-frequency bits, where the operating frequency of the high-frequency bit is higher than that of the low-frequency bit. The design advantage of this quantum chip structural parameter is that it avoids the resonance effect between adjacent quantum bits, but it will cause another problem in practical application. Figure 1 For example, since both qubit Q0 and qubit Q2 are high-frequency bits, when one of the qubits (assuming it is qubit Q0) is excited to an excited state, since the operating frequencies of the two qubits may be assigned very close, the quantum state of qubit Q0 will leak into qubit Q2, that is, the quantum state of qubit Q0 changes from an excited state to a ground state, and qubit Q2 changes to an excited state without receiving any quantum state control signal. This situation is called quantum state leakage. Once quantum state leakage occurs, serious errors will occur in quantum computing tasks.

[0005] Therefore, proposing a solution that can avoid quantum state leakage has become an urgent issue in this field.

[0006] It should be noted that the information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a quantum chip control method, device and quantum computer, which are used to solve the problem of quantum state leakage in quantum chips in the prior art.

[0008] In order to solve the above technical problems, the present invention proposes a control method for a quantum chip, comprising:

[0009] A quantum chip is provided, the quantum chip comprising a quantum bit to be measured, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the quantum bit to be measured is coupled to the first quantum bit through the first adjustable coupler, and the first quantum bit is coupled to the second quantum bit through the second adjustable coupler;

[0010] The operating frequency of the second adjustable coupler is adjusted within a first preset range to reduce the quantum state of the second quantum bit from leaking to the quantum bit to be measured.

[0011] Optionally, the method further comprises:

[0012] Obtaining an equivalent coupling strength between the quantum bit to be measured and the second quantum bit;

[0013] If the equivalent coupling strength is greater than a preset threshold, the step of adjusting the operating frequency of the second adjustable coupler within a first preset range is performed.

[0014] Optionally, the equivalent coupling strength between the quantum bit to be measured and the second quantum bit is obtained by the following formula:

[0015]

[0016] Among them, g q0,q2 is the equivalent coupling strength between the quantum bit to be measured and the second quantum bit, ω q0 is the frequency of the sub-bit to be measured, ω q1 is the frequency of the first qubit, ω q2 is the frequency of the second qubit, ω c01 is the frequency of the first adjustable coupler, ω c12 is the frequency of the second tunable coupler, g q0,c01 is the coupling strength between the subbit to be measured and the first adjustable coupler, g q1,c01 is the coupling strength between the first quantum bit and the first adjustable coupler, g q1,c12 is the coupling strength between the first quantum bit and the second adjustable coupler, g q2,c12 is the coupling strength between the second qubit and the second adjustable coupler, g q0,q1 is the coupling strength between the quantum bit to be measured and the first quantum bit, g q1,q2 is the coupling strength between the first quantum bit and the second quantum bit.

[0017] Optionally, the preset threshold of the equivalent coupling strength is determined according to the length of the quantum circuit currently executed on the quantum bit to be measured.

[0018] Optionally, the size of the preset threshold is inversely correlated with the length of the quantum circuit currently executed on the quantum bit to be measured.

[0019] Optionally, adjusting the operating frequency of the second adjustable coupler within a first preset range includes:

[0020] Adjusting the operating frequency of the second adjustable coupler within the first preset range to obtain a first change in the frequency difference between the second quantum bit and the quantum bit to be measured as a function of the adjustment amount of the operating frequency of the second adjustable coupler;

[0021] An adjustment amount of the operating frequency of the second adjustable coupler corresponding to a maximum point of the frequency difference between the second quantum bit and the quantum bit to be measured is obtained based on the first change as a first adjustment amount;

[0022] The frequency of the second adjustable coupler is adjusted using the first adjustment amount.

[0023] Optionally, adjusting the operating frequency of the second adjustable coupler within a first preset range includes:

[0024] Obtaining a second variation of the probability that the second quantum bit is in the |1> state as a function of the adjustment amount of the operating frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0025] An adjustment amount of the operating frequency of the second adjustable coupler corresponding to the minimum point of the probability that the second quantum bit is in the |1> state is obtained based on the second change as a second adjustment amount;

[0026] The frequency of the second adjustable coupler is adjusted using the second adjustment amount.

[0027] Optionally, adjusting the operating frequency of the second adjustable coupler within a first preset range includes:

[0028] Obtaining a third variation of the probability that the second quantum bit is in the |0> state as a function of the adjustment amount of the operating frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0029] An adjustment amount of the operating frequency of the second adjustable coupler corresponding to a maximum point of the probability that the second quantum bit is in the |0> state is obtained based on the third change situation as a third adjustment amount;

[0030] The frequency of the second adjustable coupler is adjusted using the third adjustment amount.

[0031] Optionally, the first preset range is determined according to the frequencies of the first quantum bit and the second quantum bit.

[0032] Based on the same inventive concept, the present invention also proposes a control device for a quantum chip, comprising:

[0033] A quantum chip providing unit, configured to provide a quantum chip, wherein the quantum chip comprises a quantum bit to be measured, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the quantum bit to be measured is coupled to the first quantum bit through the first adjustable coupler, and the first quantum bit is coupled to the second quantum bit through the second adjustable coupler;

[0034] An operating frequency adjustment unit is used to adjust the operating frequency of the second adjustable coupler within a first preset range to reduce the quantum state of the second quantum bit from leaking to the quantum bit to be measured.

[0035] Based on the same inventive concept, the present invention also proposes a quantum control system, using the control method of the quantum chip described in any one of the above-mentioned feature descriptions, or a control device including the quantum chip described in the above-mentioned feature descriptions.

[0036] Based on the same inventive concept, the present invention also proposes a quantum computer, including the quantum control system described in the above feature description.

[0037] Based on the same inventive concept, the present invention also proposes a readable storage medium on which a computer program is stored. When the computer program is executed by a processor, it can implement the control method of the quantum chip described in any one of the above-mentioned feature descriptions.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The control method of the quantum chip proposed in the present invention adjusts the operating frequency of the second adjustable coupler within a first preset range. Since the frequency of the second quantum bit is affected when the operating frequency of the second adjustable coupler is adjusted, it can be understood that adjusting the operating frequency of the second adjustable coupler will correct the frequency of the second quantum bit, thereby suppressing the occurrence of quantum state leakage. The solution of the present application effectively solves the problem of quantum state leakage in quantum chips in the prior art, and improves the accuracy of the execution results of quantum computers to a certain extent.

[0040] The control device, quantum control system, quantum computer and readable storage medium of the quantum chip proposed in the present invention belong to the same inventive concept as the control method of the quantum chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the structure of a quantum chip;

[0042] Figure 2 A schematic diagram of a flow chart of a method for controlling a quantum chip according to an embodiment of the present invention;

[0043] Figure 3 Schematic diagram of the change of the probability of the |1> state of the second quantum bit over time when quantum state leakage suppression is not performed;

[0044] Figure 4 is a schematic diagram of the variation of the probability of the |1> state of the subbit to be measured over time when quantum state leakage suppression is not performed;

[0045] Figure 5 A schematic diagram showing how the probability of the |1> state of the second quantum bit changes over time after quantum state leakage is suppressed using the solution of the present application;

[0046] Figure 6 A schematic diagram showing how the probability of the |1> state of the quantum bit to be measured changes over time after quantum state leakage is suppressed using the solution of the present application;

[0047] Figure 7 This is a simplified schematic diagram of the structure of a quantum chip control device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0048] The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

[0049] In the description of the present invention, it is necessary to understand that the terms "center", "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0050] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0051] Please refer to Figure 2 , an embodiment of the present invention provides a control method for a quantum chip, comprising:

[0052] S100: providing a quantum chip, the quantum chip comprising a quantum bit to be measured, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the quantum bit to be measured is coupled to the first quantum bit through the first adjustable coupler, and the first quantum bit is coupled to the second quantum bit through the second adjustable coupler;

[0053] S200: Adjusting the operating frequency of the second adjustable coupler within a first preset range to reduce the quantum state of the second quantum bit from leaking to the quantum bit to be measured.

[0054] The difference from the prior art is that the control method of the quantum chip proposed in this embodiment adjusts the operating frequency of the second adjustable coupler within a first preset range. Since the frequency of the second quantum bit is affected when the operating frequency of the second adjustable coupler is adjusted, it can be understood that adjusting the operating frequency of the second adjustable coupler will correct the frequency of the second quantum bit, thereby suppressing the occurrence of quantum state leakage. The solution of this application effectively solves the problem of quantum state leakage in quantum chips in the prior art, and improves the accuracy of the execution results of quantum computers to a certain extent.

[0055] From the description in the previous background technology section, it can be seen that although the quantum chip structure with high-frequency bits and low-frequency bits spaced apart can effectively avoid the resonance effect between two adjacent quantum bits, thereby avoiding the quantum state leakage phenomenon, it may cause quantum state leakage between sub-adjacent quantum bits. The occurrence of such leakage will cause serious errors in quantum computers when performing certain quantum computing tasks or quantum algorithms. In this embodiment, sub-adjacent quantum bits refer to two quantum bits in the quantum chip that have a common adjacent quantum bit, for example, Figure 1 In the quantum chip design, there are two schemes: the frequency of the quantum bit is adjustable (also known as the variable frequency bit) and the frequency of the quantum bit is not adjustable (also known as the fixed frequency bit). For the quantum chip with variable frequency bits, the quantum state leakage phenomenon can be solved well. We only need to adjust the frequency of the quantum bit where the quantum state leakage occurs. However, for the quantum chip with fixed frequency bits, since the frequency of each quantum bit has been fixed at the beginning of the quantum chip design, we cannot directly adjust the frequency of the quantum bit. At this time, we need to use the solution of this application to solve the quantum state leakage problem.

[0056] In order to improve the utilization rate of quantum chips, not every quantum bit in the quantum chip needs to suppress quantum state leakage. The applicant proposes to determine whether quantum state leakage needs to be suppressed by the equivalent coupling strength between the quantum bit to be measured and the second quantum bit. Specifically, in this embodiment, the method further includes:

[0057] Obtaining an equivalent coupling strength between the quantum bit to be measured and the second quantum bit;

[0058] If the equivalent coupling strength is greater than a preset threshold, the step of adjusting the operating frequency of the second adjustable coupler within a first preset range is performed.

[0059] Since the two qubits are not adjacent qubits, we cannot directly obtain the coupling strength through the frequencies of the two qubits. We use the following scheme to obtain the equivalent coupling strength of the two qubits. Specifically, in this embodiment, the equivalent coupling strength between the qubit to be measured and the second qubit is obtained by the following formula:

[0060]

[0061] Among them, g q0,q2 is the equivalent coupling strength between the quantum bit to be measured and the second quantum bit, ω q0 is the frequency of the sub-bit to be measured, ω q1 is the frequency of the first qubit, ω q2 is the frequency of the second qubit, ω c01 is the frequency of the first adjustable coupler, ω c12 is the frequency of the second tunable coupler, g q0,c01 is the coupling strength between the subbit to be measured and the first adjustable coupler, g q1,c01 is the coupling strength between the first quantum bit and the first adjustable coupler, g q1,c12 is the coupling strength between the first quantum bit and the second adjustable coupler, g q2,c12 is the coupling strength between the second qubit and the second adjustable coupler, g q0,q1 is the coupling strength between the quantum bit to be measured and the first quantum bit, g q1,q2 is the coupling strength between the first quantum bit and the second quantum bit. It can be understood by those skilled in the art that, in this embodiment, the g q0,c01 , g q1,c01 , g q1,c12 , g q2,c12 , g q0,q1 , g q1,q2Both can be obtained through the respective frequencies of the two devices involved in the coupling, which will not be elaborated here.

[0062] Specifically, in this embodiment, the preset threshold of the equivalent coupling strength is determined according to the length of the quantum circuit currently executed on the quantum bit to be measured.

[0063] It can be understood by those skilled in the art that the so-called quantum circuit is essentially an execution sequence of quantum logic gates, which are executed from left to right. Quantum circuits, also known as quantum logic circuits, are the most commonly used general quantum computing model, representing circuits for operating quantum bits in an abstract concept. The components include quantum bits, circuits (timelines), and various quantum logic gates. Finally, quantum measurements are often required to read out the results. Unlike traditional circuits that are connected by metal wires to transmit voltage or current signals, in quantum circuits, the circuits are connected by time, that is, the state of the quantum bit evolves naturally over time, and the process is in accordance with the instructions of the Hamiltonian operator until it encounters a quantum logic gate and is operated. Since each quantum logic gate that makes up the quantum circuit is a unitary operator, the entire quantum circuit as a whole is also a large unitary operator.

[0064] Optionally, the size of the preset threshold is inversely correlated with the length of the quantum circuit currently executed on the quantum bit to be measured. It should be noted that the length of the quantum circuit is the time required to execute the entire quantum circuit.

[0065] In order to effectively suppress the quantum state leakage phenomenon between the subbit to be measured and the second qubit, this embodiment proposes three optional examples. The first is to select the optimal adjustment amount of the operating frequency of the second adjustable coupler by obtaining the first change of the frequency difference between the second qubit and the subbit to be measured with the adjustment amount of the operating frequency of the second adjustable coupler. Specifically, in this embodiment, adjusting the operating frequency of the second adjustable coupler within the first preset range may include:

[0066] Adjusting the operating frequency of the second adjustable coupler within the first preset range to obtain a first change in the frequency difference between the second quantum bit and the quantum bit to be measured as a function of the adjustment amount of the operating frequency of the second adjustable coupler;

[0067] An adjustment amount of the operating frequency of the second adjustable coupler corresponding to a maximum point of the frequency difference between the second quantum bit and the quantum bit to be measured is obtained based on the first change as a first adjustment amount;

[0068] The frequency of the second adjustable coupler is adjusted using the first adjustment amount.

[0069] The second method is to select the optimal adjustment amount of the operating frequency of the second adjustable coupler by obtaining the second change of the probability of the second quantum bit being in the |1> state with the adjustment amount of the operating frequency of the second adjustable coupler. Specifically, in this embodiment, adjusting the operating frequency of the second adjustable coupler within the first preset range includes:

[0070] Obtaining a second variation of the probability that the second quantum bit is in the |1> state as a function of the adjustment amount of the operating frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0071] An adjustment amount of the operating frequency of the second adjustable coupler corresponding to the minimum point of the probability that the second quantum bit is in the |1> state is obtained based on the second change as a second adjustment amount;

[0072] The frequency of the second adjustable coupler is adjusted using the second adjustment amount.

[0073] The third method is to select the optimal adjustment amount of the operating frequency of the second adjustable coupler by obtaining the third change of the probability of the second quantum bit being in the |0> state with the adjustment amount of the operating frequency of the second adjustable coupler. Specifically, in this embodiment, adjusting the operating frequency of the second adjustable coupler within the first preset range includes:

[0074] Obtaining a third variation of the probability that the second quantum bit is in the |0> state as a function of the adjustment amount of the operating frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0075] An adjustment amount of the operating frequency of the second adjustable coupler corresponding to a maximum point of the probability that the second quantum bit is in the |0> state is obtained based on the third change situation as a third adjustment amount;

[0076] The frequency of the second adjustable coupler is adjusted using the third adjustment amount.

[0077] In this embodiment, the second adjustable coupler is used to couple and connect the first quantum bit and the second quantum bit. The frequency of the second adjustable coupler will be higher than the frequencies of the first quantum bit and the second quantum bit. When we suppress quantum state leakage by adjusting the operating frequency of the second adjustable coupler, we generally choose to lower the operating frequency of the second adjustable coupler, but we cannot lower the operating frequency of the second adjustable coupler to a frequency close to that of either the first quantum bit or the second quantum bit. For example, the first preset range can be set according to the frequencies of the two quantum bits, and the lower limit of the operating frequency of the second adjustable coupler is the frequency of the high-frequency bit in the two quantum bits plus 500MHz. In other embodiments, other preset ranges can also be selected, which are not limited here. Specifically, in this embodiment, the first preset range is determined according to the frequencies of the first quantum bit and the second quantum bit.

[0078] To verify the effectiveness of this application solution, please refer to Figures 3 to 6 ,in Figure 3 is the change of the probability of the |1> state of the second quantum bit over time when quantum state leakage suppression is not performed, Figure 4 When quantum state leakage suppression is not performed, the probability of the |1> state of the sub-bit to be measured changes with time. It can be clearly seen that as time goes on, the |1> state of the second quantum bit will leak to the sub-bit to be measured with a high probability, and the probability of quantum state leakage is close to 0.97. Figure 5 After quantum state leakage is suppressed by the solution of the present application, the probability of the |1> state of the second quantum bit changes with time, Figure 6 After quantum state leakage is suppressed by the solution of the present application, the probability of the |1> state of the quantum bit to be measured changes with time. It can be seen that the probability of quantum state leakage has been greatly reduced, and the highest probability is less than 0.06.

[0079] Please refer to Figure 7 Based on the same inventive concept, the present invention also proposes a control device for a quantum chip, comprising:

[0080] The quantum chip providing unit 100 is used to provide a quantum chip, wherein the quantum chip includes a quantum bit to be measured, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the quantum bit to be measured is coupled to the first quantum bit through the first adjustable coupler, and the first quantum bit is coupled to the second quantum bit through the second adjustable coupler;

[0081] The operating frequency adjustment unit 200 is used to adjust the operating frequency of the second adjustable coupler within a first preset range to reduce the quantum state of the second quantum bit from leaking to the quantum bit to be measured.

[0082] It is understood that the quantum chip providing unit 100 and the operating frequency adjustment unit 200 can be combined in one device, or any one of the modules can be split into multiple sub-modules, or at least part of the functions of one or more modules in the quantum chip providing unit 100 and the operating frequency adjustment unit 200 can be combined with at least part of the functions of other modules and implemented in one functional module. According to an embodiment of the present invention, at least one of the quantum chip providing unit 100 and the operating frequency adjustment unit 200 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented in hardware or firmware in any other reasonable way of integrating or packaging the circuit, or in a proper combination of software, hardware and firmware. Alternatively, at least one of the quantum chip providing unit 100 and the operating frequency adjustment unit 200 can be at least partially implemented as a computer program module, and when the program is run by a computer, the function of the corresponding module can be executed.

[0083] Based on the same inventive concept, the present invention also proposes a quantum control system, using the control method of the quantum chip described in any one of the above-mentioned feature descriptions, or a control device including the quantum chip described in the above-mentioned feature descriptions.

[0084] Based on the same inventive concept, the present invention also proposes a quantum computer, including the quantum control system described in the above feature description.

[0085] Based on the same inventive concept, the present invention also proposes a readable storage medium on which a computer program is stored. When the computer program is executed by a processor, it can implement the control method of the quantum chip described in any one of the above-mentioned feature descriptions.

[0086] The readable storage medium can be a tangible device that can keep and store the instructions used by the instruction execution device, such as but not limited to an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device or any suitable combination of the above. The more specific example (non-exhaustive list) of the readable storage medium includes: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a convex structure in a groove on which instructions are stored, and any suitable combination of the above. The computer program described here can be downloaded from the readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device through a network, such as the Internet, a local area network, a wide area network and / or a wireless network. The network can include copper transmission cables, optical fiber transmission, wireless transmission, routers, firewalls, switches, gateway computers and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer program from the network and forwards the computer program for storage in a readable storage medium in each computing / processing device. The computer program for performing the operation of the present invention may be an assembly instruction, an instruction set architecture (ISA) instruction, a machine instruction, a machine-dependent instruction, a microcode, a firmware instruction, a state setting data, or a source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as "C" language or similar programming languages. The computer program may be executed entirely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect through the Internet). In some embodiments, by utilizing the state information of a computer program to personalize an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), the electronic circuit can execute computer-readable program instructions to implement various aspects of the present invention.

[0087] Here, various aspects of the present invention are described with reference to the flowchart and / or block diagram of the method, system and computer program product according to the embodiment of the present invention. It should be understood that each square frame of the flowchart and / or block diagram and the combination of the square frames in the flowchart and / or block diagram can be realized by a computer program. These computer programs can be provided to the processor of a general-purpose computer, a special-purpose computer or other programmable data processing device, so as to produce a machine, so that these programs, when executed by the processor of a computer or other programmable data processing device, produce a device for realizing the function / action specified in one or more square frames in the flowchart and / or block diagram. These computer programs can also be stored in a readable storage medium, and these computer programs make the computer, programmable data processing device and / or other equipment work in a specific way, so that the readable storage medium storing the computer program includes a manufactured product, which includes instructions for realizing various aspects of the function / action specified in one or more square frames in the flowchart and / or block diagram.

[0088] The computer program may also be loaded onto a computer, other programmable data processing apparatus, or other device so that a series of operational steps are executed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the computer program executed on the computer, other programmable data processing apparatus, or other device to implement the functions / actions specified in one or more boxes in the flowchart and / or block diagram.

[0089] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example" or "specific example" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0090] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A method for controlling a quantum chip, characterized in that: include: A quantum chip is provided, the quantum chip comprising a quantum bit to be measured, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the quantum bit to be measured is coupled to the first quantum bit through the first adjustable coupler, and the first quantum bit is coupled to the second quantum bit through the second adjustable coupler; The operating frequency of the second adjustable coupler is adjusted within a first preset range to reduce the quantum state of the second quantum bit from leaking to the quantum bit to be measured.

2. The method according to claim 1, characterized in that The method further comprises: Obtaining an equivalent coupling strength between the quantum bit to be measured and the second quantum bit; If the equivalent coupling strength is greater than a preset threshold, the step of adjusting the operating frequency of the second adjustable coupler within a first preset range is performed.

3. The method according to claim 2, characterized in that The equivalent coupling strength between the quantum bit to be measured and the second quantum bit is obtained by the following formula: Among them, g q0,q2 is the equivalent coupling strength between the quantum bit to be measured and the second quantum bit, ω q0 is the frequency of the sub-bit to be measured, ω q1 is the frequency of the first qubit, ω q2 is the frequency of the second qubit, ω c01 is the frequency of the first adjustable coupler, ω c12 is the frequency of the second tunable coupler, g q0,c01 is the coupling strength between the subbit to be measured and the first adjustable coupler, g q1,c01 is the coupling strength between the first quantum bit and the first adjustable coupler, g q1,c12 is the coupling strength between the first quantum bit and the second adjustable coupler, g q2,c12 is the coupling strength between the second qubit and the second adjustable coupler, g q0,q1 is the coupling strength between the quantum bit to be measured and the first quantum bit, g q1,q2 is the coupling strength between the first quantum bit and the second quantum bit.

4. The method according to claim 2, characterized in that The preset threshold of the equivalent coupling strength is determined according to the length of the quantum circuit currently executed on the quantum bit to be measured.

5. The method according to claim 4, characterized in that The size of the preset threshold is inversely correlated with the length of the quantum circuit currently executed on the quantum bit to be measured.

6. The method according to claim 1, characterized in that The step of adjusting the operating frequency of the second adjustable coupler within the first preset range comprises: Adjusting the operating frequency of the second adjustable coupler within the first preset range to obtain a first change in the frequency difference between the second quantum bit and the quantum bit to be measured as a function of the adjustment amount of the operating frequency of the second adjustable coupler; An adjustment amount of the operating frequency of the second adjustable coupler corresponding to a maximum point of the frequency difference between the second quantum bit and the quantum bit to be measured is obtained based on the first change as a first adjustment amount; The frequency of the second adjustable coupler is adjusted using the first adjustment amount.

7. The method according to claim 1, characterized in that The step of adjusting the operating frequency of the second adjustable coupler within the first preset range comprises: Obtaining a second variation of the probability of the second quantum bit being in the |1> state as a function of the adjustment amount of the operating frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state; An adjustment amount of the operating frequency of the second adjustable coupler corresponding to the minimum point of the probability that the second quantum bit is in the |1> state is obtained based on the second change as a second adjustment amount; The frequency of the second adjustable coupler is adjusted using the second adjustment amount.

8. The method according to claim 1, characterized in that The step of adjusting the operating frequency of the second adjustable coupler within the first preset range comprises: Obtaining a third variation of the probability that the second quantum bit is in the |0> state as a function of the adjustment amount of the operating frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state; An adjustment amount of the operating frequency of the second adjustable coupler corresponding to a maximum point of the probability that the second quantum bit is in the |0> state is obtained based on the third change situation as a third adjustment amount; The frequency of the second adjustable coupler is adjusted using the third adjustment amount.

9. The method according to claim 1, characterized in that The first preset range is determined according to the frequencies of the first quantum bit and the second quantum bit.

10. A control device for a quantum chip, characterized in that: include: A quantum chip providing unit, configured to provide a quantum chip, wherein the quantum chip comprises a quantum bit to be measured, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the quantum bit to be measured is coupled to the first quantum bit through the first adjustable coupler, and the first quantum bit is coupled to the second quantum bit through the second adjustable coupler; An operating frequency adjustment unit is used to adjust the operating frequency of the second adjustable coupler within a first preset range to reduce the quantum state of the second quantum bit from leaking to the quantum bit to be measured.

11. A quantum control system, characterized in that: A control method using the quantum chip as described in any one of claims 1 to 9, or a control device comprising the quantum chip as described in claim 10.

12. A quantum computer, characterized in that: Comprising the quantum control system as claimed in claim 11.

13. A readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, it can implement the control method of the quantum chip according to any one of claims 1 to 9.

Images