Method and apparatus for controlling quantum chip, and quantum computer

Abstract

The application discloses a quantum chip control method and device and a quantum computer. The working frequency of the second adjustable coupler is adjusted in a first preset range. Since the working frequency of the second adjustable coupler is adjusted, the frequency of the second quantum bit is affected, that is, the working frequency of the second adjustable coupler is adjusted to correct the frequency of the second quantum bit, thereby inhibiting the occurrence of quantum state leakage. The scheme of the application effectively solves the quantum state leakage problem of the quantum chip in the prior art, and improves the accuracy of the execution result of the quantum computer to a certain extent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum computing, and in particular to a quantum chip control method and device and a quantum computer. BACKGROUND

[0002] Quantum computing and quantum information is a cross-discipline based on the principles of quantum mechanics to achieve computing and information processing tasks, which has a very close relationship with quantum physics, computer science, information science and other disciplines, and has developed rapidly in the past two decades. Quantum algorithms based on quantum computers for factorization and unstructured search scenarios have shown performance far superior to existing algorithms based on classical computers, and have also been expected to exceed existing computing capabilities. Since quantum computing has the potential to far exceed the performance of classical computers in solving certain problems, in order to implement a quantum computer, a quantum chip containing a sufficient number and quality of quantum bits is needed, and quantum logic gate operations and reading with high fidelity on quantum bits are required.

[0003] A quantum chip is equivalent to a CPU for a traditional computer, and is the core component of a quantum computer. The quantum chip is a processor that performs quantum computing, and integrates a plurality of quantum bits and reading cavities that are one-to-one corresponding and coupled to each other. Each quantum chip needs to be tested and characterized before being formally 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 devices located at room temperature and low-temperature devices and signal transmission lines located inside a dilution refrigerator. After the quantum chip is packaged, it is fixed to the extremely low-temperature layer at the bottom of the dilution refrigerator and finally connected to the hardware devices at room temperature through coaxial lines between layers. In the measurement and control system, two types of lines are mainly used when regulating the quantum state of the quantum bit. One is the first type of transmission line (i.e., the quantum state control line) for driving the quantum state of the quantum bit, and the other is the second type of transmission line (i.e., the frequency control line) for regulating the frequency of the quantum bit.

[0004] In the quantum bit expansion architecture based on an adjustable coupler, two quantum bits can be coupled through a fixed capacitive coupling and an adjustable coupler with adjustable coupling coefficient. The adjustable coupler is similar in structure to 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 between adjacent quantum bits and adjustable couplers due to too small a frequency difference, when assigning the working frequencies of the quantum bits and the adjustable couplers, the frequency of the adjustable coupler is generally set higher, so that the frequency of the quantum bit is lower than that of the adjustable coupler. Figure 1 For example, the quantum chip shown in the figure has Q0, Q1, Q2, Q3, Q5, and Q6 as quantum bits, C0, C1, C2, C3, C5, and C6 as adjustable couplers, and C0, C1, C2, C3, C5, and C6 as adjustable couplers.01 , C 12 , C 23 , C 03 , C 15 , C 56 , C 26 The adjustable coupler can set the working frequency in the range of 6-8GHz, the working frequency of the quantum bit can be set in the range of 4-5GHz, and the frequency between the adjacent two quantum bits also presents high and low frequency changes, for example, if the quantum bit Q0 is set as a high frequency bit, then the quantum bit Q1 is set as a low frequency bit, and the quantum bits Q2 and Q5 need to be set as high frequency bits, wherein the working frequency of the high frequency bit is higher than that of the low frequency bit. The design advantage of such quantum chip structure parameters is to avoid the resonance influence between adjacent quantum bits, but another problem will be caused in actual application, still taking Figure 1 as an example, since the quantum bit Q0 and the quantum bit Q2 are both high frequency bits, when one of the quantum bits (assuming it is the quantum bit Q0) is excited to the excited state, since the working frequencies of the two quantum bits can be allocated very close to each other, the quantum state of the quantum bit Q0 will leak into the quantum bit Q2, that is, the quantum state of the quantum bit Q0 changes from the excited state to the ground state, and the quantum bit Q2 becomes the excited state without receiving any quantum state control signal, which is called quantum state leakage. Once quantum state leakage occurs, it will cause serious errors in quantum computing tasks.

[0005] Therefore, a scheme that can avoid quantum state leakage is proposed, which is an urgent problem in the field.

[0006] It should be noted that the information disclosed in the background section of the present application is only intended to deepen the understanding of the general background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. SUMMARY

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

[0008] In order to solve the above technical problems, the present application provides a quantum chip control method, which comprises:

[0009] A quantum chip is provided, which 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 and the first quantum bit are coupled and connected through the first adjustable coupler, and the first quantum bit and the second quantum bit are coupled and connected through the second adjustable coupler.

[0010] adjusting a working frequency of the second tunable coupler within a first preset range to reduce quantum state leakage of the second qubit onto the to-be-measured qubit.

[0011] Optionally, the method further comprises:

[0012] obtaining an equivalent coupling strength between the to-be-measured qubit and the second qubit;

[0013] if the equivalent coupling strength is greater than a preset threshold, performing the adjusting the working frequency of the second tunable coupler within the first preset range.

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

[0015]

[0016] wherein, g q0,q2 is the equivalent coupling strength between the to-be-measured qubit and the second qubit, ω q0 is a frequency of the to-be-measured qubit, ω q1 is a frequency of the first qubit, ω q2 is a frequency of the second qubit, ω c01 is a frequency of the first tunable coupler, ω c12 is a frequency of the second tunable coupler, g q0,c01 is a coupling strength between the to-be-measured qubit and the first tunable coupler, g q1,c01 is a coupling strength between the first qubit and the first tunable coupler, g q1,c12 is a coupling strength between the first qubit and the second tunable coupler, g q2,c12 is a coupling strength between the second qubit and the second tunable coupler, g q0,q1 is a coupling strength between the to-be-measured qubit and the first qubit, g q1,q2 is a coupling strength between the first qubit and the second qubit.

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

[0018] Optionally, the preset threshold is inversely related to the length of the quantum circuit currently executed on the to-be-measured qubit.

[0019] Optionally, the adjusting the working frequency of the second tunable coupler within the first preset range comprises:

[0020] adjusting the working frequency of the second adjustable coupler within the first preset range, to obtain a first change condition of the frequency difference between the second quantum bit and the to-be-measured quantum bit with respect to the adjustment amount of the working frequency of the second adjustable coupler;

[0021] obtaining, based on the first change condition, a first adjustment amount of the working frequency of the second adjustable coupler corresponding to a maximum point of the frequency difference between the second quantum bit and the to-be-measured quantum bit;

[0022] adjusting the frequency of the second adjustable coupler by using the first adjustment amount.

[0023] Optionally, the adjusting the working frequency of the second adjustable coupler within the first preset range comprises:

[0024] obtaining a second change condition of the probability of the second quantum bit being in the |1> state with respect to the adjustment amount of the working frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0025] obtaining, based on the second change condition, a second adjustment amount of the working frequency of the second adjustable coupler corresponding to a minimum point of the probability of the second quantum bit being in the |1> state;

[0026] adjusting the frequency of the second adjustable coupler by using the second adjustment amount.

[0027] Optionally, the adjusting the working frequency of the second adjustable coupler within the first preset range comprises:

[0028] obtaining a third change condition of the probability of the second quantum bit being in the |0> state with respect to the adjustment amount of the working frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0029] obtaining, based on the third change condition, a third adjustment amount of the working frequency of the second adjustable coupler corresponding to a maximum point of the probability of the second quantum bit being in the |0> state;

[0030] adjusting the frequency of the second adjustable coupler by 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 application further provides a control device of a quantum chip, comprising:

[0033] The quantum chip providing unit is configured to provide a quantum chip, which 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] The working frequency adjusting unit is configured to adjust the working frequency of the second adjustable coupler within a first preset range, so as to reduce quantum state leakage of the second quantum bit to the quantum bit to be measured.

[0035] Based on the same inventive concept, the present application further provides a quantum control system, which utilizes the control method of the quantum chip according to any one of the above features or the control device of the quantum chip according to the above features.

[0036] Based on the same inventive concept, the present application further provides a quantum computer, which comprises the quantum control system according to the above features.

[0037] Based on the same inventive concept, the present application further provides a readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the control method of the quantum chip according to any one of the above features.

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

[0039] The control method of the quantum chip adjusts the working frequency of the second adjustable coupler within a first preset range. When the working frequency of the second adjustable coupler is adjusted, the frequency of the second quantum bit is affected, which can be understood as that adjusting the working frequency of the second adjustable coupler corrects the frequency of the second quantum bit, thereby inhibiting the occurrence of quantum state leakage. The scheme of the present application effectively solves the problem of quantum state leakage of the quantum chip in the prior art, and improves the accuracy of the execution result of the quantum computer to a certain extent.

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

[0041] Figure 1 FIG. 1 is a structural schematic diagram of a quantum chip;

[0042] Figure 2 FIG. 4 is a flowchart of the control method of the quantum chip according to an embodiment of the present application;

[0043] Figure 3 Fig. 2 is a schematic diagram of the |1> state probability of the second qubit over time without quantum state leakage suppression;

[0044] Figure 4 Fig. 3 is a schematic diagram of the |1> state probability of the to-be-measured qubit over time without quantum state leakage suppression;

[0045] Figure 5 Fig. 4 is a schematic diagram of the |1> state probability of the second qubit over time after quantum state leakage suppression by the scheme of the present application;

[0046] Figure 6 Fig. 5 is a schematic diagram of the |1> state probability of the to-be-measured qubit over time after quantum state leakage suppression by the scheme of the present application;

[0047] Figure 7 Fig. 6 is a schematic diagram of the structure of the control device of the quantum chip according to another embodiment of the present application. DETAILED DESCRIPTION

[0048] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. The advantages and features of the present application will be more apparent from the following description and claims. It should be noted that the drawings are very simplified and use non-precise proportions, only to facilitate, clarify the purpose of assisting the description of the embodiments of the present application.

[0049] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "left", "right" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0050] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0051] Please refer to Figure 2 The embodiment of the present application proposes a control method of 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, a second adjustable coupler, wherein the quantum bit to be measured and the first quantum bit are coupled by the first adjustable coupler, and the first quantum bit and the second quantum bit are coupled by the second adjustable coupler;

[0053] S200: adjusting the working frequency of the second adjustable coupler within a first preset range to reduce quantum state leakage of the second quantum bit to the quantum bit to be measured.

[0054] The difference from the prior art is that the control method of the quantum chip adjusts the working frequency of the second adjustable coupler within a first preset range. Since adjusting the working frequency of the second adjustable coupler will affect the frequency of the second quantum bit, it can be understood that adjusting the working frequency of the second adjustable coupler will correct the frequency of the second quantum bit, thereby suppressing the occurrence of quantum state leakage. The scheme of the present application effectively solves the problem of quantum state leakage in the quantum chip in the prior art, and to some extent improves the accuracy of the execution result of the quantum computer.

[0055] From the description in the background section, it can be seen that although the quantum chip structure with high-frequency bits and low-frequency bits arranged in intervals can effectively avoid the resonance influence between two adjacent quantum bits, thereby avoiding the occurrence of quantum state leakage, it may cause quantum state leakage between the next adjacent quantum bits. The occurrence of such leakage will cause serious errors in the execution of certain quantum computing tasks or quantum algorithms by the quantum computer. In the present embodiment, the next adjacent quantum bits refer to two quantum bits in the quantum chip that have a common adjacent quantum bit, for example, Figure 1 quantum bit Q0 and quantum bit Q2 in FIG. 1, quantum bit Q0 and quantum bit Q5, and the like. In the design of the quantum chip, there are two schemes including frequency-adjustable quantum bits (i.e., variable-frequency bits) and frequency-unadjustable quantum bits (i.e., fixed-frequency bits). For the quantum chip with variable-frequency bits, the quantum state leakage phenomenon can be well solved by adjusting 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 fixedly designed at the beginning of the design of the quantum chip, the frequency of the quantum bit cannot be directly adjusted. At this time, the scheme of the present application is needed to solve the quantum state leakage problem.

[0056] In order to improve the utilization rate of the quantum chip, not every quantum bit in the quantum chip needs to be subjected to quantum state leakage suppression, and the applicant proposes to determine whether the quantum state leakage suppression needs to be performed through the equivalent coupling strength between the to-be-measured quantum bit and the second quantum bit. Specifically, in the embodiment, the method further comprises:

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

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

[0059] Since the two quantum bits are not adjacent two quantum bits, we cannot directly obtain the coupling strength through the frequencies of the two quantum bits, and we obtain the equivalent coupling strength of the two quantum bits by using the following scheme. Specifically, in the embodiment, the equivalent coupling strength between the to-be-measured quantum bit and the second quantum bit is obtained by the following formula:

[0060]

[0061] wherein g q0,q2 is the equivalent coupling strength between the to-be-measured quantum bit and the second quantum bit, ω q0 is the frequency of the to-be-measured quantum bit, ω q1 is the frequency of the first quantum bit, ω q2 is the frequency of the second quantum bit, ω c01 is the frequency of the first adjustable coupler, ω c12 is the frequency of the second adjustable coupler, g q0,c01 is the coupling strength between the to-be-measured quantum bit 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 quantum bit and the second adjustable coupler, g q0,q1 is the coupling strength between the to-be-measured quantum bit 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 the embodiment, the g q0,c01 , g q1,c01 , g q1,c12 , g q2,c12 , g q0,q1 , g q1,q2Both can be obtained by participating in the frequency of the two devices coupled to each other, hereinafter.

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

[0063] As can be understood by those skilled in the art, a quantum circuit is essentially a sequence of quantum logic gates, which is executed from left to right. Quantum circuit, also known as quantum logic circuit, is the most commonly used general quantum computing model, which represents the line of operations on quantum bits in an abstract concept. The composition includes quantum bits, lines (time lines), and various quantum logic gates. Finally, quantum measurement is often needed to read the results. Unlike traditional circuits, which are connected by metal wires to transmit voltage signals or current signals, in quantum circuits, the lines are connected by time, that is, the state of the quantum bit naturally evolves over time, following the instructions of the Hamiltonian operator, until it encounters a quantum logic gate and is operated. Since each quantum logic gate that constitutes a 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 related to the length of the quantum circuit currently executed on the to-be-measured quantum bit. 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 to-be-measured quantum bit and the second quantum bit, the present embodiment proposes three alternative examples, the first of which is to select the optimal adjustment amount of the working frequency of the second adjustable coupler by obtaining the first change of the frequency difference between the second quantum bit and the to-be-measured quantum bit with the adjustment amount of the working frequency of the second adjustable coupler. Specifically, in the present embodiment, the adjustment of the working frequency of the second adjustable coupler within the first preset range can include:

[0066] Adjusting the working frequency of the second adjustable coupler within the first preset range, obtaining the first change of the frequency difference between the second quantum bit and the to-be-measured quantum bit with the adjustment amount of the working frequency of the second adjustable coupler;

[0067] Based on the first change, the adjustment amount of the working frequency of the second adjustable coupler corresponding to the maximum point of the frequency difference between the second quantum bit and the to-be-measured quantum bit is the first adjustment amount;

[0068] Adjusting the frequency of the second adjustable coupler using the first adjustment amount.

[0069] The second is to select the optimal adjustment amount of the working frequency of the second adjustable coupler by acquiring a second variation of a probability of the second quantum bit being in the |1> state with respect to an adjustment amount of the working frequency of the second adjustable coupler. Specifically, in the embodiment, the adjusting the working frequency of the second adjustable coupler in the first preset range comprises:

[0070] acquiring a second variation of a probability of the second quantum bit being in the |1> state with respect to an adjustment amount of the working frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0071] acquiring, based on the second variation, a second adjustment amount of the working frequency of the second adjustable coupler corresponding to a minimum point of the probability of the second quantum bit being in the |1> state;

[0072] adjusting the frequency of the second adjustable coupler by using the second adjustment amount.

[0073] The third is to select the optimal adjustment amount of the working frequency of the second adjustable coupler by acquiring a third variation of a probability of the second quantum bit being in the |0> state with respect to an adjustment amount of the working frequency of the second adjustable coupler. Specifically, in the embodiment, the adjusting the working frequency of the second adjustable coupler in the first preset range comprises:

[0074] acquiring a third variation of a probability of the second quantum bit being in the |0> state with respect to an adjustment amount of the working frequency of the second adjustable coupler, wherein the initial state of the second quantum bit is the |0> state;

[0075] acquiring, based on the third variation, a third adjustment amount of the working frequency of the second adjustable coupler corresponding to a maximum point of the probability of the second quantum bit being in the |0> state;

[0076] adjusting the frequency of the second adjustable coupler by using the third adjustment amount.

[0077] In the embodiment, the second adjustable coupler is used to couple the first quantum bit and the second quantum bit, and the frequency of the second adjustable coupler is higher than the frequencies of the first quantum bit and the second quantum bit. When the quantum state leakage is suppressed by adjusting the working frequency of the second adjustable coupler, the working frequency of the second adjustable coupler is generally lowered, but the working frequency of the second adjustable coupler cannot be lowered to a frequency close to the frequency of any one of the first quantum bit and the second quantum bit. For example, the first preset range can be set according to the frequencies of the first quantum bit and the second quantum bit, and the lower limit of the working frequency of the second adjustable coupler is the frequency of the high-frequency bit of the two quantum bits plus 500 MHz. In other embodiments, other preset ranges can also be selected, which are not limited herein. Specifically, in the 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 effect of the scheme, refer to Figures 3 to 6 , wherein Figure 3 is the probability of the |1> state of the second quantum bit over time when the quantum state leakage is not suppressed, Figure 4 is the probability of the |1> state of the to-be-measured quantum bit over time when the quantum state leakage is not suppressed. It can be obviously seen that, as time goes on, the |1> state of the second quantum bit leaks to the to-be-measured quantum bit, and the probability is high, and the probability of quantum state leakage is close to 0.97. Figure 5 is the probability of the |1> state of the second quantum bit over time after the quantum state leakage is suppressed by using the scheme, Figure 6 is the probability of the |1> state of the to-be-measured quantum bit over time after the quantum state leakage is suppressed by using the scheme. 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 application further provides a control device of a quantum chip, comprising:

[0080] The quantum chip providing unit 100 is configured to provide a quantum chip, and the quantum chip comprises a to-be-measured quantum bit, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler. The to-be-measured quantum bit and the first quantum bit are coupled by the first adjustable coupler, and the first quantum bit and the second quantum bit are coupled by the second adjustable coupler.

[0081] The working frequency adjusting unit 200 is configured to adjust the working frequency of the second adjustable coupler within a first preset range, so as to reduce quantum state leakage of the second quantum bit to the quantum bit to be measured.

[0082] It can be understood that the quantum chip providing unit 100 and the working frequency adjusting 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 of the quantum chip providing unit 100 and the working frequency adjusting 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 application, at least one of the quantum chip providing unit 100 and the working frequency adjusting 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 chip, a system on substrate, a system on package, an application specific integrated circuit (ASIC), or any other reasonable way of integrating or packaging circuits, etc. hardware or firmware, or a suitable combination of software, hardware and firmware. Alternatively, at least one of the quantum chip providing unit 100 and the working frequency adjusting unit 200 can be at least partially implemented as a computer program module that can perform the functions of the corresponding module when the program is run by a computer.

[0083] Based on the same inventive concept, the present application further provides a quantum control system using the quantum chip control method described in any one of the above feature descriptions or the quantum chip control device described in the above feature descriptions.

[0084] Based on the same inventive concept, the present application further provides a quantum computer comprising the quantum control system described in the above feature descriptions.

[0085] Based on the same inventive concept, the present application further provides a readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the quantum chip control method described in any one of the above feature descriptions.

[0086] The readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The readable storage medium can be, for example but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the readable storage medium include the following: a portable computer diskette, 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 disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or punched tape, a holographic storage medium, or any suitable combination of the foregoing. A computer program product, such as the computer program 1120, can be downloaded to the respective computing / processing device from a readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network, and / or a wireless network. The network can comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives computer program product from the network and forwards the computer program product for storage in a readable storage medium in the respective computing / processing device. The computer program 1120 for carrying out operations of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer program 1120 can execute entirely on the user's computing / processing device, partly on the user's computing / processing device, as a stand-alone software package, partly on the user's computing / processing device and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computing / processing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate array (FPGA), or programmable logic array (PLA) can execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present application.

[0087] The computer program can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the computer program running on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0088] The computer program can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the computer program running on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0089] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments. In addition, those skilled in the art can combine and integrate different embodiments or examples described in the specification.

[0090] The above are only preferred embodiments of the present application, and do not have any limiting effect on the present application. Any person skilled in the art can make any form of equivalent replacement or modification, etc. to the technical solutions and technical contents disclosed in the present application without departing from the scope of the technical solutions of the present application, which still belongs to the protection scope of the present application.

Claims

1. A method of controlling a quantum chip, characterized by, The method comprises: providing a quantum chip, the quantum chip comprising a to-be-measured quantum bit, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the to-be-measured quantum bit 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; adjusting a working frequency of the second adjustable coupler within a first preset range to reduce quantum state leakage of the second quantum bit to the to-be-measured quantum bit; The method further comprises: obtaining an equivalent coupling strength between the to-be-measured quantum bit and the second quantum bit; if the equivalent coupling strength is greater than a preset threshold, performing the adjusting of the working frequency of the second adjustable coupler within the first preset range; wherein the preset threshold is determined according to a length of a quantum circuit currently executed on the to-be-measured quantum bit.

2. The method of claim 1, wherein, The equivalent coupling strength between the to-be-measured quantum bit and the second quantum bit is obtained by the following formula: wherein g q0,q2 is the effective coupling strength between the to-be-measured qubit and the second qubit, ω q0 is the frequency of the to-be-measured qubit, 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 adjustable coupler, g q0,c01 is the coupling strength between the to-be-measured qubit and the first adjustable coupler, g q1,c01 is the coupling strength between the first qubit and the first adjustable coupler, g q1,c12 is the coupling strength between the first qubit 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 to-be-measured qubit and the first qubit, g q1,q2 is the coupling strength between the first qubit and the second qubit.

3. The method of claim 1, wherein, The size of the preset threshold is inversely related to the length of the quantum circuit currently executed on the to-be-measured quantum bit.

4. The method of claim 1, wherein, The adjusting of the working frequency of the second adjustable coupler within the first preset range comprises: adjusting the working frequency of the second adjustable coupler within the first preset range to obtain a first change of a frequency difference between the second quantum bit and the to-be-measured quantum bit with respect to an adjustment amount of the working frequency of the second adjustable coupler; obtaining, based on the first change, a first adjustment amount of the working frequency of the second adjustable coupler corresponding to a maximum point of the frequency difference between the second quantum bit and the to-be-measured quantum bit; adjusting the frequency of the second adjustable coupler by using the first adjustment amount.

5. The method of claim 1, wherein, The adjusting of the working frequency of the second adjustable coupler within the first preset range comprises: obtaining a second change of a probability of the second quantum bit being in a |1> state with respect to an adjustment amount of the working frequency of the second adjustable coupler, wherein an initial state of the second quantum bit is a |0> state; obtaining, based on the second change, a second adjustment amount of the working frequency of the second adjustable coupler corresponding to a minimum point of the probability of the second quantum bit being in the |1> state; adjusting the frequency of the second adjustable coupler by using the second adjustment amount.

6. The method of claim 1, wherein, The adjusting of the working frequency of the second adjustable coupler within the first preset range comprises: obtaining a third change of a probability of the second quantum bit being in a |0> state with respect to an adjustment amount of the working frequency of the second adjustable coupler, wherein an initial state of the second quantum bit is the |0> state; obtaining, based on the third change, a third adjustment amount of the working frequency of the second adjustable coupler corresponding to a maximum point of the probability of the second quantum bit being in the |0> state; adjusting the frequency of the second adjustable coupler by using the third adjustment amount.

7. The method of claim 1, wherein, The first preset range is determined according to frequencies of the first quantum bit and the second quantum bit.

8. A control device of a quantum chip, characterized by, The method comprises: The quantum chip providing unit is configured to provide a quantum chip, the quantum chip comprising a to-be-measured quantum bit, a first quantum bit, a second quantum bit, a first adjustable coupler, and a second adjustable coupler, wherein the to-be-measured quantum bit and the first quantum bit are coupled to each other through the first adjustable coupler, and the first quantum bit and the second quantum bit are coupled to each other through the second adjustable coupler. The working frequency adjusting unit is configured to adjust a working frequency of the second adjustable coupler within a first preset range, so as to reduce quantum state leakage of the second quantum bit to the to-be-measured quantum bit. The device further comprises: The equivalent coupling strength obtaining unit is configured to obtain an equivalent coupling strength between the to-be-measured quantum bit and the second quantum bit. The calling unit is configured to call the working frequency adjusting unit to perform the adjusting of the working frequency of the second adjustable coupler within the first preset range, if the equivalent coupling strength is greater than a preset threshold value, wherein the preset threshold value is determined according to a length of a quantum circuit currently executed on the to-be-measured quantum bit.

9. A quantum control system, characterized by, The control method of the quantum chip according to any one of claims 1-7 or the control device comprising the quantum chip according to claim 8.

10. A quantum computer, characterized by, The quantum control system according to claim 9.

11. A readable storage medium, having stored thereon a computer program, characterized in that, The computer program is executed by a processor to implement the control method of the quantum chip according to any one of claims 1-7. The computer program is executed by a processor to implement the control method of the quantum chip according to any one of claims 1-7.

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