Method, device, equipment, medium and product for regulating double quantum bit gate

Abstract

The application provides a method, device, equipment, medium and product for regulating a two-qubit gate. The method comprises: determining a quantum drive frequency of a quantum drive signal applied to a quantum coupler to couple a first qubit and a second qubit to each other, in a case where the first qubit and the second qubit are coupled via the quantum coupler located between the first qubit and the second qubit; frequency doubling the quantum drive frequency to obtain a frequency-doubled value; determining a target resonance frequency for the quantum coupler based on the frequency-doubled value, a first intrinsic frequency of the first qubit and a second intrinsic frequency of the second qubit; and controlling the quantum coupler to operate at the target resonance frequency to regulate a coupling strength between the first qubit and the second qubit.

Description

Technical Field

[0001] This application relates to the field of quantum computing technology, specifically to a method, device, equipment, medium, and product for controlling a two-qubit gate. Background Technology

[0002] Superconducting quantum chips are a highly feasible mainstream physical platform in the field of quantum computing, and the precision of their control is one of the key technologies restricting the precision of quantum manipulation. In superconducting qubit systems with integrated quantum couplers, due to the complexity of the energy level structure and the nonlinear mapping relationship between the change in magnetic flux of the quantum coupler and the coupling strength between qubits, multiple stray frequency components are generated outside the driving frequency when a driving signal is applied to the quantum coupler, causing frequency collision problems and thus reducing the control fidelity of the qubits. Summary of the Invention

[0003] In view of the above problems, embodiments of this application provide a method, apparatus, device, medium and product for controlling a two-qubit gate.

[0004] According to a first aspect of the embodiments of this application, a method, apparatus, device, medium, and product for controlling a two-qubit gate are provided. The control method includes: determining a quantum drive frequency of a quantum drive signal applied to the quantum coupler to couple the first and second qubits together, wherein the first qubit and the second qubit are coupled via a quantum coupler located between the first and second qubits; multiplying the quantum drive frequency to obtain a frequency multiplication value; determining a target resonant frequency for the quantum coupler based on the frequency multiplication value, a first eigenfrequency of the first qubit, and a second eigenfrequency of the second qubit; and controlling the quantum coupler to operate at the target resonant frequency to control the coupling strength between the first and second qubits.

[0005] According to an embodiment of this application, determining a target resonant frequency for a quantum coupler based on the doubling value, the first intrinsic frequency of the first qubit, and the second intrinsic frequency of the second qubit includes: determining a resonant frequency value for the quantum coupler to generate an energy level transition based on the doubling value, the first intrinsic frequency, and the second intrinsic frequency; and determining a target resonant frequency for the quantum coupler within a preset interval in response to the current resonant frequency of the quantum coupler being equal to the resonant frequency value.

[0006] According to embodiments of this application, the resonant frequency value is one of the following: the difference between the harmonic value and the first intrinsic frequency, the sum of the harmonic value and the first intrinsic frequency, the difference between the harmonic value and the second intrinsic frequency, or the sum of the harmonic value and the second intrinsic frequency.

[0007] According to an embodiment of this application, in response to the current resonant frequency of the quantum coupler being equal to the resonant frequency value, a target resonant frequency for the quantum coupler is determined within a preset interval, including: determining multiple fitted resonant frequencies of the quantum coupler within a preset interval according to a preset step size; when a quantum driving signal is applied to the quantum coupler and the quantum coupler is controlled to operate sequentially at multiple fitted resonant frequencies, acquiring the actual excitation value of the quantum coupler corresponding to each fitted resonant frequency that causes an energy level transition; and determining the target resonant frequency from the multiple fitted resonant frequencies based on the actual excitation value corresponding to each fitted resonant frequency.

[0008] According to an embodiment of this application, when the quantum coupler operates at any two resonant frequencies within a preset range, the absolute value of the difference in coupling strength between the first quantum bit and the second quantum bit is less than or equal to a preset threshold.

[0009] According to an embodiment of this application, determining the target resonant frequency for a quantum coupler based on the doubling value, the first eigenfrequency of the first qubit, and the second eigenfrequency of the second qubit further includes: determining the current resonant frequency as the target resonant frequency in response to the current resonant frequency of the quantum coupler not being equal to the resonant frequency value.

[0010] According to a second aspect of the embodiments of this application, a control device for a two-qubit gate is provided. The control device includes a first determining module, a frequency doubling module, a second determining module, and a control module. The first determining module is used to determine the quantum driving frequency of a quantum driving signal applied to the quantum coupler to couple the first and second qubits to each other, when the first qubit and the second qubit are coupled via a quantum coupler located between the first and second qubits. The frequency doubling module is used to multiply the quantum driving frequency to obtain a frequency doubling value. The second determining module is used to determine a target resonant frequency for the quantum coupler based on the frequency doubling value, a first eigenfrequency of the first qubit, and a second eigenfrequency of the second qubit. The control module is used to control the quantum coupler to operate at the target resonant frequency to regulate the coupling strength between the first and second qubits.

[0011] According to a third aspect of the embodiments of this application, an electronic device is provided. The electronic device includes one or more processors and a memory. The memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the above-described control method.

[0012] According to a fourth aspect of the embodiments of this application, a computer-readable storage medium is provided, on which executable instructions are stored, which, when executed by a processor, cause the processor to implement the above-described control method.

[0013] According to a fifth aspect of the embodiments of this application, a computer program product is provided. The product includes a computer program that, when executed by a processor, implements the aforementioned control method.

[0014] According to embodiments of this application, a method, apparatus, device, medium, and product for controlling a two-qubit gate are provided. In this method, when a first qubit and a second qubit are coupled via a quantum coupler located between the first and second qubits, the target resonant frequency of the quantum coupler is determined based on the frequency doubling term of the quantum driving frequency, the first eigenfrequency of the first qubit, and the second eigenfrequency of the second qubit. This avoids frequency components that cause frequency conflicts derived from the quantum driving frequency, alleviates the real excitation problem of the quantum coupler, and thereby improves the control fidelity of the two-qubit gate. Attached Figure Description

[0015] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, which will be explained below in conjunction with the drawings:

[0016] Figure 1 A schematic diagram illustrating the system energy level structure of two qubits and a quantum coupler according to an embodiment of this application is shown.

[0017] Figure 2 The diagram illustrates the distribution of the control error rate of a two-qubit gate in a related technology.

[0018] Figure 3 The diagram schematically illustrates the architecture of a control method for a two-qubit gate according to an embodiment of this application;

[0019] Figure 4 A flowchart illustrating a method for controlling a two-qubit gate according to an embodiment of this application is shown schematically.

[0020] Figure 5 The waveform of the quantum drive signal according to an embodiment of this application is illustrated schematically;

[0021] Figure 6 The diagram illustrates the distribution of the modulation error rate of a two-qubit gate in an embodiment of this application as a function of the resonant frequency of the quantum coupler.

[0022] Figure 7 The diagram illustrates the characteristic curves of the coupling strength of the two-qubit gate versus the resonant frequency of the quantum coupler in an embodiment of this application.

[0023] Figure 8 A schematic diagram of the structure of a control device for a two-qubit gate according to an embodiment of this application is shown.

[0024] Figure 9 A block diagram of an electronic device suitable for implementing a control method for a two-qubit gate according to an embodiment of this application is shown schematically. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0026] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this application.

[0027] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0028] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0029] In the description of this application, it should be understood that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] Similarly, to simplify this application and aid in understanding one or more of the various disclosed aspects, in the above description of exemplary embodiments of this application, various features of this application are sometimes grouped together into a single embodiment, figure, or description thereof. The use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0031] Superconducting quantum chips are a highly feasible mainstream physical platform in the field of quantum computing, and the precision of their control is one of the key technologies restricting the precision of quantum manipulation. In superconducting qubit systems with integrated quantum couplers, due to the complexity of the energy level structure and the nonlinear mapping relationship between the change in magnetic flux of the quantum coupler and the coupling strength between qubits, multiple stray frequency components are generated outside the driving frequency when a driving signal is applied to the quantum coupler, causing frequency collision problems and thus reducing the control fidelity of the qubits.

[0032] Figure 1 A schematic diagram illustrating the system energy level structure of two qubits and a quantum coupler according to an embodiment of this application is provided. It should be noted that... Figure 1 |ψ q1 ψ c ψ q2 >Characterizes the quantum states of two qubits and a quantum coupler, where ψ q1 Let ψ be the quantum state of the first qubit. c Let ψ be the quantum state of the quantum coupler. q2 This represents the quantum state of the second qubit.

[0033] like Figure 1As shown, |000> can be characterized as the ground state of the system's energy level structure, where the first qubit, quantum coupler, and second qubit are all in the ground state, serving as the initial reference state for two-qubit gate control; |100> can be characterized as the first qubit being in the first excited state, with both the quantum coupler and second qubit in the ground state; |200> can be characterized as the first qubit being in the second excited state, with both the quantum coupler and second qubit in the ground state; |001> can be characterized as the second qubit being in the first excited state, with both the first qubit and quantum coupler in the ground state; |010> can be characterized as the quantum coupler being in the first excited state, with both the first and second qubits in the ground state; |101> can be characterized as the first and second qubits being in the first excited state, with the quantum coupler in the ground state. Similarly, Figure 1 |ψ q1 ψ c ψ q2 The quantum states of the system's energy level structure were characterized respectively.

[0034] Continue to refer to Figure 1 The solid lines represent the intrinsic energy levels of the system's energy level structure, while the dashed lines represent leakage energy levels that may be excited by energy level transitions. Where ω... target The quantum driving frequency, representing the quantum driving signal that couples the first and second qubits, can correspond to the transition frequencies of |200> and |101>; ω lc1 The first-kind resonance frequency representing the energy level transitions of a quantum coupler can correspond to the transition frequencies between |100> and |010>, and between |101> and |011>. ω lc2 The second type of resonance frequency representing the energy level transition of a quantum coupler can correspond to the transition frequencies between |010> and |001>, and between |110> and |101>; ω leak The leakage transition frequency, corresponding to the transition frequencies of |101> and |002>, is the core harmful path causing miscontrol of two-qubit gates. It allows the qubit population to escape the preset computational subspace, reducing the control fidelity of the two-qubit gate. Δ can represent the tunable offset of the quantum coupler resonant frequency.

[0035] Figure 2 The diagram illustrates the distribution of the control error rate of a two-qubit gate in a related technology. It should be noted that... Figure 2 The horizontal axis represents the difference in intrinsic frequencies between the first and second qubits, in GHz, and the vertical axis represents the control error rate of the two-qubit gate. Δlc1 and Δlc2 represent the corresponding frequencies at which the energy level transitions of the quantum coupler form resonance.

[0036] like Figure 2As shown, when the intrinsic frequency difference is far from the positions Δlc1 and Δlc2, the modulation error rate of the two-qubit gate remains at 10. －4 ~10 －3 Within the lower order of magnitude, this indicates relatively good control fidelity. When the intrinsic frequency difference is at or near the positions of Δlc1 and Δlc2, the control error rate of the two-qubit gate increases sharply, even exceeding 10^- ... －2 The magnitude of the difference in intrinsic frequencies leads to high error spikes. When the harmonic value of the difference in intrinsic frequencies matches the frequency at which the quantum coupler resonates, it triggers unnecessary energy level transitions in the quantum coupler, i.e., it triggers real excitation effects, increasing the control error rate of the two-qubit gate.

[0037] In view of this, embodiments of this application provide a method, apparatus, device, medium, and product for controlling a two-qubit gate, which can greatly alleviate the real excitation problem of quantum couplers, thereby reducing the control error rate of the two-qubit gate and having better robustness.

[0038] Figure 3 A schematic diagram illustrates the architecture of a control method for a two-qubit gate according to an embodiment of this application.

[0039] like Figure 3 As shown, ω q1 The first eigenfrequency of the first qubit, denoted as ω, characterizes the transition frequency of the first qubit from its ground state to its first excited state; q2 ω is represented as the second eigenfrequency of the second qubit, which characterizes the transition frequency of the second qubit from its ground state to its first excited state. drive The quantum drive frequency, denoted as ω, is the quantum drive signal applied to the quantum coupler. target The double-headed arrow on one side represents the range of energy level transitions covered by the quantum driving signal. n can be represented as the order of the energy level transition. lc1 and ω lc2 This represents the coupling transition frequency between the quantum coupler and the first and second qubits, respectively. Figure 2 The resonant frequency at which the quantum coupler generates a real excitation effect. ω c The resonant frequency of the quantum coupler is represented by the double-headed arrow on one side, indicating that the resonant frequency is continuously tunable. Tuning of the quantum coupler's resonant frequency can be achieved by applying a DC bias signal to the quantum coupler. By changing the resonant frequency of the quantum coupler, ω can be shifted. lc1 ω lc2 The value of is used to alleviate the real excitation problem of quantum couplers.

[0040] The following will be based on Figure 3 The described scene, through Figures 4-9 A method for controlling a two-qubit gate according to embodiments of this application will be described in detail.

[0041] Figure 4 A flowchart illustrating a method for controlling a two-qubit gate according to an embodiment of this application is shown.

[0042] like Figure 4 As shown, the control method of this embodiment may include operations S410 to S440.

[0043] In operation S410, when the first qubit and the second qubit are coupled via a quantum coupler located between the first qubit and the second qubit, the quantum drive frequency of the quantum drive signal applied to the quantum coupler to couple the first qubit and the second qubit to each other is determined.

[0044] Figure 5 A waveform diagram of a quantum drive signal according to an embodiment of this application is illustrated schematically.

[0045] like Figure 5 As shown, the horizontal axis represents the driving time of the quantum driving signal in ns; the vertical axis represents the amplitude of the magnetic flux generated by the quantum driving signal in Φ0. The quantum driving signal driving the first and second qubits to couple with each other can be an AC driving signal containing multiple cycles. In some embodiments, envelope shaping can be performed on the edge positions (start edge and end edge) of the quantum driving signal to suppress high-frequency spurious components and reduce additional transition excitations. The quantum driving frequency can be the center frequency of the quantum driving signal driving the energy level transitions of the qubits.

[0046] By operating S420, the quantum drive frequency is multiplied to obtain the multiplied value.

[0047] During the application of the quantum driving signal, due to the nonlinear mapping relationship between the change in magnetic flux of the quantum coupler and the coupling strength between the qubits, the quantum driving signal will generate a quantum driving frequency ω. target Other frequency components, such as the harmonic value nω of the quantum drive frequency. target n is a positive integer greater than 1. (Continue to refer to...) Figure 2 and Figure 3 The frequency harmonic value nω of the quantum drive frequency target The coupling transition frequency ω between the quantum coupler and the first qubit lc1 Or the coupling transition frequency ω between the quantum coupler and the second quantum bit lc2 When they match, the problem of real excitation of quantum couplers arises.

[0048] In operation S430, the target resonant frequency for the quantum coupler is determined based on the frequency doubling value, the first eigenfrequency of the first qubit, and the second eigenfrequency of the second qubit.

[0049] The first eigenfrequency ω of the first quantum bit q1 ω can be the transition frequency of the first qubit from its ground state to its first excited state, and ω can be the second eigenfrequency of the second qubit. q2 It can be the transition frequency of the second quantum bit from the ground state to the first excited state.

[0050] Based on the harmonic value nω target The first eigenfrequency ω of the first quantum bit q1 The second eigenfrequency ω of the second quantum bit q2 The target resonant frequency ω for the quantum coupler can be determined. ct .

[0051] In operation of S440, the quantum coupler is controlled to operate at the target resonant frequency in order to regulate the coupling strength between the first and second qubits.

[0052] According to an embodiment of this application, when the first qubit and the second qubit are coupled via a quantum coupler located between the first qubit and the second qubit, the method determines the target resonant frequency of the quantum coupler based on the frequency doubling term of the quantum driving frequency, the first eigenfrequency of the first qubit, and the second eigenfrequency of the second qubit. This can avoid frequency components that cause frequency conflicts derived from the quantum driving frequency, alleviate the real excitation problem of the quantum coupler, and thereby improve the control fidelity of the two-qubit gate.

[0053] In some embodiments, the resonant frequency value at which the quantum coupler generates energy level transitions can be determined based on the harmonic value, the first eigenfrequency, and the second eigenfrequency.

[0054] Continue to refer to Figure 2 and Figure 3 The conditions for triggering the real excitation problem of a quantum coupler need to satisfy either formula (1) or formula (2).

[0055] nω target =|ω c -ω q1 | (1);

[0056] nω target =|ω c -ω q2 | (2);

[0057] Where, nω target ω represents the harmonic value of the quantum drive frequency. targetω represents the quantum drive frequency. c ω represents the resonant frequency of the quantum coupler. q1 ω q2 These represent the first eigenfrequency of the first qubit and the second eigenfrequency of the second qubit, respectively.

[0058] According to formulas (1) and (2), the resonant frequency ω of the energy level transition caused by the real excitation problem in the quantum coupler is... cl It can be expressed as formula (3) or formula (4).

[0059] ω cl =ω q1 ±nω target (3);

[0060] ω cl =ω q2 ±nω target (4);

[0061] Based on this, the resonant frequency value of a quantum coupler can be one of the following: the difference between the harmonic value and the first intrinsic frequency, the sum of the harmonic value and the first intrinsic frequency, the difference between the harmonic value and the second intrinsic frequency, or the sum of the harmonic value and the second intrinsic frequency.

[0062] When the current resonant frequency of the quantum coupler is equal to the resonant frequency value, the target resonant frequency for the quantum coupler can be determined within a preset range, so that the target resonant frequency of the quantum coupler avoids the resonant frequency value that triggers the real excitation problem.

[0063] According to embodiments of this application, by determining the resonant frequency value of the quantum coupler that causes the real excitation problem, and adjusting the resonant frequency of the quantum coupler to the target resonant frequency within a preset range, the waveform of the quantum driving signal can be changed. The value of the coupling transition frequency can be shifted simply by adjusting the resonant frequency of the quantum coupler to the target resonant frequency within a preset range, thereby alleviating the real excitation problem of the quantum coupler.

[0064] In some embodiments, when the current resonant frequency of the quantum coupler is not equal to the resonant frequency value, the current resonant frequency of the quantum coupler can be determined as the target resonant frequency.

[0065] In some embodiments, when the quantum coupler operates at any two resonant frequencies within a preset range, the absolute value of the difference in coupling strength between the first qubit and the second qubit can be less than or equal to a preset threshold. The preset threshold can be set according to the specific application, ensuring that the variation in coupling strength between the first and second qubits is small, and the residual coupling strength remains within an acceptable range for the specific application. In this embodiment, the preset range can be on the order of hundreds of megahertz.

[0066] According to embodiments of this application, adjusting the resonant frequency of the quantum coupler within a preset range can alleviate the real excitation problem of the quantum coupler with minimal impact on the coupling characteristics between the first and second qubits, thereby improving the control fidelity.

[0067] In some embodiments, the target resonant frequency of the quantum coupler can be determined by a continuous traversal scanning method with a single parameter. For example, multiple fitted resonant frequencies of the quantum coupler can be determined within a preset interval according to a preset step size; while applying a quantum driving signal to the quantum coupler and controlling the quantum coupler to operate sequentially at multiple fitted resonant frequencies, the real excitation value of the quantum coupler corresponding to the energy level transition at each fitted resonant frequency is collected; based on the real excitation value corresponding to each fitted resonant frequency, the target resonant frequency is determined from the multiple fitted resonant frequencies. In this embodiment, the quantum driving signal is fixed during the scanning process.

[0068] According to the embodiments of this application, the method can determine the target resonant frequency of the quantum coupler through a relatively simple single-dimensional scanning method, which is suitable for the measurement and control requirements of large-scale superconducting quantum chips and has a wide range of experimental applications.

[0069] Figure 6 The diagram illustrates the distribution of the modulation error rate of a two-qubit gate in an embodiment of this application as a function of the resonant frequency of the quantum coupler. Figure 7 The diagram illustrates the characteristic curves of the coupling strength of a two-qubit gate versus the resonant frequency of the quantum coupler in an embodiment of this application.

[0070] like Figure 6 As shown, the horizontal axis is ω c / 2π, in GHz, ω c The ordinate represents the resonant frequency of the quantum coupler, and the vertical axis represents the modulation error rate of the two-qubit gate. When the resonant frequency of the quantum coupler is around 2π × 8.2 GHz, the modulation error rate is around 10. －3 The magnitude; as the resonant frequency approaches 2π×8.5GHz, the modulation error rate gradually decreases, reaching 10. －4 On the order of magnitude; as the resonant frequency continues to shift towards 2π×8.7GHz, the modulation error rate gradually reaches 10. －2 Magnitude. Based on Figure 6 A resonant frequency of 2π×8.5GHz can be selected to alleviate the real excitation problem of the quantum coupler.

[0071] like Figure 7 As shown, the horizontal axis is ω c / 2π, in GHz, ω c The resonant frequency of the quantum coupler is represented by the left vertical axis, which is g. xx / 2π, unit: MHz, gxx The x-axis represents the coupling strength between two qubits along the x-axis, i.e., the XX-type coupling strength; the right vertical axis represents g. zz / 2π, unit: MHz, g zz The coupling strength between two qubits along the Z-axis is called the ZZ-type coupling strength. XX-type coupling is the core coupling type controlling the interaction between qubits, while ZZ-type coupling is a parasitic coupling type controlling the interaction between qubits. Both XX-type and ZZ-type coupling strengths gradually increase with the resonant frequency of the quantum coupler. The increase in XX-type coupling strength is close to linear, while the increase in ZZ-type coupling strength is non-linear, and the ZZ-type coupling strength is 1-2 orders of magnitude lower than the XX-type coupling strength. Figure 7 The resonant frequency of the quantum coupler can be adjusted within a preset range to control the XX-type coupling strength and ZZ-type coupling strength.

[0072] Figure 8 A schematic block diagram of a control device for a two-qubit gate according to an embodiment of this application is shown.

[0073] like Figure 8 As shown, the control device 800 may include a first determining module 810, a frequency doubling module 820, a second determining module 830, and a control module 840.

[0074] The first determining module 810 is used to determine, when the first qubit and the second qubit are coupled via a quantum coupler located between the first qubit and the second qubit, the quantum driving frequency of the quantum driving signal applied to the quantum coupler to couple the first qubit and the second qubit to each other. In one embodiment, the first determining module 810 may be used to perform the operation S410 described above, which will not be repeated here.

[0075] The frequency multiplication module 820 is used to multiply the quantum drive frequency to obtain a frequency multiplication value. In one embodiment, the frequency multiplication module 820 can be used to perform the operation S420 described above, which will not be repeated here.

[0076] The second determining module 830 is used to determine the target resonant frequency for the quantum coupler based on the frequency doubling value, the first eigenfrequency of the first qubit, and the second eigenfrequency of the second qubit. In one embodiment, the second determining module 830 may be used to perform the operation S430 described above, which will not be repeated here.

[0077] The control module 840 is used to control the quantum coupler to operate at a target resonant frequency, thereby regulating the coupling strength between the first and second qubits. In one embodiment, the control module 840 may be used to perform the operation S440 described above, which will not be repeated here.

[0078] According to embodiments of this application, any plurality of modules among the first determining module 810, frequency multiplier module 820, second determining module 830, and control module 840 can be combined into one module. Alternatively, any one of these modules can be split into multiple modules. Or, at least part of the functionality of one or more of these modules can be combined with at least part of the functionality of other modules and implemented in one module. According to embodiments of this application, at least one of the first determining module 810, frequency multiplier module 820, second determining module 830, and control module 840 can be at least partially implemented as hardware circuitry, 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-package, an application-specific integrated circuit (ASIC), or implemented in hardware or firmware by any other reasonable means of integrating or packaging the circuitry, or implemented in any one of the three implementation methods of software, hardware, and firmware, or in a suitable combination of any of these. Alternatively, at least one of the first determining module 810, the frequency multiplication module 820, the second determining module 830, and the control module 840 may be at least partially implemented as a computer program module, which can perform corresponding functions when the computer program module is run.

[0079] Figure 9 A block diagram of an electronic device suitable for implementing a control method for a two-qubit gate according to an embodiment of this application is shown schematically.

[0080] like Figure 9 As shown, a charging device 900 according to an embodiment of this application includes a processor 901, which can perform various appropriate actions and processes according to a program stored in a ROM 902 or a program loaded from a storage portion 908 into a RAM 903. The ROM is a read-only memory, and the RAM is a random access memory. The processor 901 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor, and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)). The processor 901 may also include onboard memory for caching purposes. The processor 901 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of this application.

[0081] RAM 903 stores various programs and data required for the operation of the charging device 900. Processor 901, ROM 902, and RAM 903 are interconnected via bus 904. Processor 901 executes various operations of the method flow according to embodiments of this application by executing programs in ROM 902 and / or RAM 903. It should be noted that the programs may also be stored in one or more memories other than ROM 902 and RAM 903. Processor 901 may also execute various operations of the method flow according to embodiments of this application by executing programs stored in said one or more memories.

[0082] According to embodiments of this application, the charging device 900 may further include an input / output (I / O) interface 905, which is also connected to a bus 904. The charging device 900 may also include one or more of the following components connected to the input / output (I / O) interface 905: an input section 906 including a keyboard, mouse, etc.; an output section 907 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 908 including a hard disk, etc.; and a communication section 909 including a network interface card such as a LAN card, modem, etc. The communication section 909 performs communication processing via a network such as the Internet. A driver 910 is also connected to the input / output (I / O) interface 905 as needed. A removable medium 911, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the driver 910 as needed so that computer programs read from it can be installed into the storage section 908 as needed.

[0083] This application also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0084] According to embodiments of this application, the computer-readable storage medium can be a non-volatile computer-readable storage medium. Examples include, but are not limited to: portable computer disks, hard disks, RAM, ROM, erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of this application, the computer-readable storage medium may include ROM 902 and / or RAM 903 and / or one or more memories other than ROM 902 and RAM 903 described above.

[0085] Embodiments of this application also include a computer program product, which includes a computer program containing program code for performing the methods provided in the embodiments of this application. When the computer program product is run in a computer system, the program code is used to enable the computer system to implement the battery charging control method for trains provided in the embodiments of this application.

[0086] When the computer program is executed by the processor 901, it performs the functions defined in the system / apparatus of this application embodiment. According to the embodiments of this application, the systems, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0087] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and may be downloaded and installed via the communication section 909, and / or installed from a removable medium 911. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0088] In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 909, and / or installed from the removable medium 911. When the computer program is executed by the processor 901, it performs the functions defined in the system of this application embodiment. According to the embodiments of this application, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0089] According to embodiments of this application, program code for executing the computer programs provided in the embodiments of this application can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C", or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0090] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0091] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

[0092] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A method for controlling a two-qubit gate, characterized in that, include: In the case where the first qubit and the second qubit are coupled via a quantum coupler located between the first qubit and the second qubit, the quantum driving frequency of the quantum driving signal applied to the quantum coupler to couple the first qubit and the second qubit to each other is determined. The quantum driving frequency is multiplied by two to obtain the multiplied frequency value; Based on the frequency doubling value, the first eigenfrequency of the first qubit and the second eigenfrequency of the second qubit, the target resonant frequency for the quantum coupler is determined. The quantum coupler is controlled to operate at the target resonant frequency to modulate the coupling strength between the first qubit and the second qubit.

2. The control method according to claim 1, characterized in that, Determining the target resonant frequency for the quantum coupler based on the frequency doubling value, the first eigenfrequency of the first qubit, and the second eigenfrequency of the second qubit includes: Based on the harmonic value, the first eigenfrequency, and the second eigenfrequency, the resonant frequency value at which the quantum coupler generates energy level transitions is determined; In response to the current resonant frequency of the quantum coupler being equal to the resonant frequency value, the target resonant frequency for the quantum coupler is determined within a preset range.

3. The control method according to claim 2, characterized in that, The resonant frequency value is one of the following: the difference between the harmonic value and the first intrinsic frequency, the sum of the harmonic value and the first intrinsic frequency, the difference between the harmonic value and the second intrinsic frequency, or the sum of the harmonic value and the second intrinsic frequency.

4. The control method according to claim 2, characterized in that, The step of determining the target resonant frequency for the quantum coupler within a preset interval in response to the current resonant frequency of the quantum coupler being equal to the resonant frequency value includes: The quantum coupler is determined within the preset interval according to a preset step size; When the quantum driving signal is applied to the quantum coupler and the quantum coupler is controlled to operate sequentially at multiple fitted resonant frequencies, the real excitation value of the quantum coupler that causes energy level transitions at each fitted resonant frequency is collected; The target resonant frequency is determined from a plurality of fitted resonant frequencies based on the actual excitation value corresponding to each fitted resonant frequency.

5. The control method according to any one of claims 2 to 4, characterized in that, When the quantum coupler operates at any two resonant frequencies within the preset range, the absolute value of the difference in coupling strength between the first quantum bit and the second quantum bit is less than or equal to a preset threshold.

6. The control method according to claim 2, characterized in that, Determining the target resonant frequency for the quantum coupler based on the frequency doubling value, the first eigenfrequency of the first qubit, and the second eigenfrequency of the second qubit further includes: In response to the fact that the current resonant frequency of the quantum coupler is not equal to the resonant frequency value, the current resonant frequency is determined as the target resonant frequency.

7. A control device for a two-qubit gate, characterized in that, include: The first determining module is configured to determine, in the case where the first qubit and the second qubit are coupled via a quantum coupler located between the first qubit and the second qubit, the quantum driving frequency of a quantum driving signal applied to the quantum coupler to couple the first qubit and the second qubit to each other; The frequency doubling module is used to multiply the quantum driving frequency to obtain a frequency doubling value; The second determining module is used to determine the target resonant frequency for the quantum coupler based on the frequency doubling value, the first eigenfrequency of the first qubit and the second eigenfrequency of the second qubit. A control module is used to control the quantum coupler to operate at the target resonant frequency in order to regulate the coupling strength between the first quantum bit and the second quantum bit.

8. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs. Wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the method of any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, It stores executable instructions that, when executed by a processor, cause the processor to implement the method of any one of claims 1 to 6.

10. A computer program product, characterized in that, It includes a computer program that, when executed by a processor, implements the method according to any one of claims 1 to 6.

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