State adjustment method, device, electronic device and storage medium based on single quantum bit gate

Abstract

This application discloses a state adjustment method, device, electronic device, and storage medium based on a single-qubit gate, relating to qubit gate state control technology. The method includes: performing charge drive and flux drive on a superconducting qubit Fluxonium equivalent circuit; adjusting the amplitudes of an AC voltage source and an AC current source respectively to equalize the Rabi oscillation frequency of the flux drive and the charge drive; adjusting the drive frequency and the qubit frequency to meet resonance conditions; adjusting the dimensionless envelope function and the phases of the charge drive and flux drive to rotate about a rotation axis located in a first coordinate plane; and adjusting the rotation axis to different rotation angles to represent different states of the qubit. This application enables superconducting qubits to have both a low leakage error rate and fast single-quantum gate operation.

Description

Technical Field

[0001] The present application relates to quantum bit gate state control technology, and in particular to a state adjustment method, device, electronic device and storage medium based on a single quantum bit gate. Background Art

[0002] Currently, the most widely used superconducting qubit is the Transmon, which features a high qubit frequency, a fast bit gate operation rate, and a relatively simple structure, facilitating the design and integration of quantum circuits. A highly precise single-qubit gate typically requires a qubit frequency significantly greater than the frequency of the Rabi oscillation. This is because the theory of single-qubit gate operations employs the rotational wave approximation, which holds true only if the qubit frequency is significantly greater than the Rabi oscillation frequency. Transmon superconducting qubits have a relatively high qubit frequency. Driven by charge generated by capacitive coupling with a voltage source, Transmon superconducting qubits can precisely implement single-qubit gate operations using the rotational wave approximation. Summary of the Invention

[0003] The present application provides a state adjustment method, device, electronic device and storage medium based on a single-qubit gate to at least solve the above technical problems existing in the prior art.

[0004] According to a first aspect of the present application, a state adjustment method based on a single-qubit gate is provided, comprising:

[0005] The superconducting quantum bit Fluxonium equivalent circuit is charged and flux driven, where the charge drive is achieved through a capacitively coupled AC voltage source, and the flux drive is achieved through the induction of an AC current source;

[0006] The amplitudes of the AC voltage source and the AC current source are respectively adjusted to make the Rabi oscillation frequency of the flux drive equal to the Rabi oscillation frequency of the charge drive; the phase difference between the charge drive and the flux drive is set to a first set value, and the drive frequency and the quantum bit frequency are adjusted to meet the resonance condition; the dimensionless envelope function and the phase of the charge drive and the flux drive are adjusted to rotate about the rotation axis located in the first coordinate plane;

[0007] By adjusting the rotation axis of the first coordinate plane to different rotation angles, different states of the quantum bit can be represented.

[0008] In some optional embodiments, the dimensionless reduction operator includes:

[0009] Reduced momentum operator ;Reduced flux operator ,in, is the basic charge, is the charge operator, which is the charge of the Cooper pair, represents the magnetic flux quantum, which is a constant;

[0010] And, the fixed flux Transformed into reduced fixed flux ,for: ; The time-dependent magnetic flux Transformed into reduced time-dependent magnetic flux ,for: ;

[0011] The Hamiltonian operator is:

[0012]

[0013] in, is the capacitance energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the external voltage, is the inductance energy of the equivalent circuit, is the superconducting loop inductance, is the Josephson energy of the equivalent circuit.

[0014] In some optional embodiments, the method further comprises:

[0015] The Hamiltonian operator is adaptively transformed, that is, the quadratic term of the Hamiltonian operator is expanded and the non-operator term is omitted, as follows:

[0016]

[0017] Where, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0018]

[0019] For charge drive, It is driven by magnetic flux;

[0020] Apply the Hamiltonian operator of the undriven Fluxonium to the ground state and the first excited state On the Hilbert space of the quantum bit expanded by the basis vector, its form is:

[0021]

[0022] Among them, the Pauli matrix ; is the qubit frequency, Equal to the energy difference between the first excited state and the ground state;

[0023] reduced flux operator In the Hilbert space of quantum bits, it is proportional to , the reduced momentum operator Proportional to ;

[0024] The Hamiltonian operator on the Hilbert space of quantum bits is of the form:

[0025]

[0026] in, is the charge-driven Rabi oscillation frequency, is the flux-driven Rabi oscillation frequency, are the frequencies of charge drive and flux drive, is the phase of the charge drive, is the phase difference between charge drive and flux drive; is a dimensionless envelope function.

[0027] In some optional embodiments, the rotation angle of the rotation axis is determined by the following integral relationship:

[0028]

[0029] represents the angle variable that changes with time, is the Rabi frequency, is a dimensionless envelope function, and the polar coordinates of the rotation axis in the first coordinate plane are (cosφ, -sinφ).

[0030] In some optional embodiments, adjusting the rotation axis of the first coordinate plane to different rotation angles to represent different states of the quantum bit includes:

[0031] Based on quantum gates , adjust the rotation angle of the rotating axis by using the arbitrary waveform generator, and change the initial base state Conversion to the first excited state ,as follows ：

[0032] And adjust the drive phase to 0;

[0033] Based on quantum gates , adjust the rotation angle of the rotating axis through the arbitrary waveform generator, state into superposition state ,as follows:

[0034]

[0035] And adjust the drive phase to .

[0036] According to a second aspect of the present application, a state adjustment device based on a single-qubit gate is provided, comprising:

[0037] A driving unit, used to perform charge driving and flux driving on the superconducting quantum bit Fluxonium equivalent circuit, wherein the charge driving is achieved by a capacitively coupled AC voltage source, and the flux driving is achieved by induction of an AC current source;

[0038] an adjustment unit for adjusting the amplitudes of the AC voltage source and the AC current source, respectively, so that the Rabi oscillation frequency of the flux drive is equal to the Rabi oscillation frequency of the charge drive; setting the phase difference between the charge drive and the flux drive to a first set value, adjusting the drive frequency and the qubit frequency to meet the resonance condition; and adjusting the dimensionless envelope function and the phases of the charge drive and the flux drive to rotate about the rotation axis located in the first coordinate plane;

[0039] The state characterization unit is used to characterize different states of the quantum bit by adjusting the rotation axis of the first coordinate plane to different rotation angles.

[0040] In some optional embodiments, the dimensionless reduction operator includes:

[0041] Reduced momentum operator ;Reduced flux operator ,in, is the basic charge, is the charge operator, which is the charge of the Cooper pair, represents the magnetic flux quantum, which is a constant;

[0042] And, the fixed flux Transformed into reduced fixed flux ,for: ; The time-dependent magnetic flux Transformed into reduced time-dependent magnetic flux ,for: ;

[0043] The Hamiltonian operator is:

[0044]

[0045] in, is the capacitance energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the external voltage, is the inductance energy of the equivalent circuit, is the superconducting loop inductance, is the Josephson energy of the equivalent circuit.

[0046] In some optional embodiments, the device further comprises:

[0047] The transformation unit is used to adaptively transform the Hamiltonian operator, that is, to expand the quadratic terms of the Hamiltonian operator and omit the non-operator terms, as follows:

[0048]

[0049] Where, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0050]

[0051] For charge drive, It is driven by magnetic flux;

[0052] Apply the Hamiltonian operator of the undriven Fluxonium to the ground state and the first excited state On the Hilbert space of the quantum bit expanded by the basis vector, its form is:

[0053]

[0054] Among them, the Pauli matrix ; is the qubit frequency, Equal to the energy difference between the first excited state and the ground state;

[0055] reduced flux operator In the Hilbert space of quantum bits, it is proportional to , the reduced momentum operator Proportional to ;

[0056] The Hamiltonian operator on the Hilbert space of quantum bits is of the form:

[0057]

[0058] in, is the charge-driven Rabi oscillation frequency, is the flux-driven Rabi oscillation frequency, are the frequencies of charge drive and flux drive, is the phase of the charge drive, is the phase difference between charge drive and flux drive; is a dimensionless envelope function.

[0059] In some optional embodiments, the rotation angle of the rotation axis is determined by the following integral relationship:

[0060]

[0061] represents the angle variable that changes with time, is the Rabi frequency, is a dimensionless envelope function, and the polar coordinates of the rotation axis in the first coordinate plane are (cosφ, -sinφ).

[0062] In some optional implementations, the state representation unit is further configured to:

[0063] Based on quantum gates , adjust the rotation angle of the rotating axis by using the arbitrary waveform generator, and change the initial base state Conversion to the first excited state ,as follows ：

[0064] And adjust the drive phase to 0;

[0065] Based on quantum gates , adjust the rotation angle of the rotating axis through the arbitrary waveform generator, state into superposition state ,as follows:

[0066]

[0067] And adjust the drive phase to .

[0068] According to a third aspect of the present application, an electronic device is provided, including:

[0069] at least one processor; and

[0070] a memory communicatively connected to the at least one processor; wherein,

[0071] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the steps of the state adjustment method based on the single-qubit gate described in the present application.

[0072] According to a fourth aspect of the present application, a non-transitory computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to enable the computer to execute the steps of the state adjustment method based on a single quantum bit gate described in the present application.

[0073] The state adjustment method, apparatus, device, and storage medium based on a single-qubit gate in this application adjust the state of the single-qubit gate by controlling the rotation axis within the first coordinate plane of the Fluxonium equivalent circuit, thereby representing different quantum information indications. This prevents errors caused by the failure of the rotational wave approximation, even at high speeds. The technical solution of this application has the advantage of high anharmonicity, enabling superconducting qubits to achieve both low leakage error rates and fast single-quantum gate operations.

[0074] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] The above and other objects, features and advantages of the exemplary embodiments of the present application will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present application are shown in an illustrative and non-limiting manner, in which:

[0076] In the drawings, the same or corresponding reference numerals denote the same or corresponding parts.

[0077] Figure 1 The equivalent circuit diagram of Fluxonium according to an embodiment of the present application is shown;

[0078] Figure 2 A schematic diagram of a flow chart of a state adjustment method based on a single-qubit gate according to an embodiment of the present application is shown;

[0079] Figure 3 The equivalent circuit of Fluxonium in the embodiment of the present application is shown as a Fluxonium driving schematic diagram;

[0080] Figure 4 A schematic diagram of the structure of a state adjustment device based on a single-qubit gate according to an embodiment of the present application is shown;

[0081] Figure 5 A schematic diagram of the structure of an electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0082] In order to make the purpose, features, and advantages of this application more obvious and easy to understand, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0083] Quantum computing is a computing paradigm based on the principles of quantum mechanics. Unlike the classical bits 0 and 1 of classical computing, quantum computing uses quantum bits State and state. State and The states are two mutually orthogonal vectors, which are expanded into a two-dimensional Hilbert space. The quantum bit can be in any vector in this space, such as the superposition state. In physical implementation, two energy eigenstates of a physical system with different energies are generally used to represent State and state.

[0084] Superconducting quantum computing is a mainstream technical route for realizing quantum computing, which uses superconducting materials and quantum circuits to realize quantum bits. The most important physical device is the superconducting Josephson junction, which can make the superconducting circuit produce anharmonic energy level structure, which is different from the equidistant energy level structure formed by the simple harmonic oscillation of the oscillation (LC) circuit. The main advantages of superconducting quantum circuits are strong scalability and fast quantum bit gate operations. Fast quantum bit gate operations are very important because a large number of quantum gate operations are required for large-scale quantum computing, and fast quantum gate responses can greatly shorten the time of quantum computing. Superconducting quantum bits State and The states usually correspond to the ground state and the first excited state, and the energy level difference corresponds to the quantum bit frequency. The implementation of a single quantum bit gate usually requires applying a microwave pulse to the quantum bit to achieve State and The higher the frequency of the Rabi oscillation, the faster the quantum bit gate.

[0085] The embodiment of the present application uses a superconducting quantum bit Fluxonium single quantum bit gate to control the different states of the quantum bit. Figure 1 The equivalent circuit diagram of Fluxonium of the embodiment of the present application is shown as follows: Figure 1 As shown in Figure 1, a Fluxonium superconducting quantum bit is composed of a superconducting Josephson junction and a superconducting inductor in parallel. The superconducting inductor is composed of many superconducting Josephson junctions in series, and its equivalent circuit element is an inductor. Figure 1 As shown, the equivalent circuit of Fluxonium consists of capacitors , Josephson junction (Josephson energy ), inductor L is connected in parallel and one end is grounded. Fixed magnetic flux This fixed magnetic flux is induced by a DC current source across the Josephson junction and the inductor loop. This flux is set to , called the "sweet spot", this setting makes the quantum bit least sensitive to flux noise. The dynamic variable of the circuit is the node flux .

[0086] Figure 2 FIG. 4 shows a flow chart of a state adjustment method based on a single quantum bit gate according to an embodiment of the present application. Figure 2 As shown, the state adjustment method based on the single-qubit gate in the embodiment of the present application includes the following processing steps:

[0087] Step 201: Charge drive and flux drive are performed on the superconducting quantum bit Fluxonium equivalent circuit.

[0088] In the embodiment of the present application, the charge drive is realized by a capacitively coupled AC voltage source, and the flux drive is realized by induction of an AC current source. Specifically, the charge drive and flux drive can be applied to the Fluxonium equivalent circuit, such as Figure 3 As shown, the Fluxonium superconducting qubit is driven by a charge through a capacitively coupled alternating voltage source and a magnetic flux through an alternating current source. Specifically, the qubit is connected to a capacitor via a Connect an AC voltage source V(t) and a fixed magnetic flux through the Josephson junction and the inductor loop. becomes .in, is the time-dependent magnetic flux, induced by an AC current source.

[0089] According to classical circuit theory, the Lagrangian of the Fluxonium equivalent circuit of the embodiment of the present application is:

[0090]

[0091] Josephson junction flux The conjugate momentum of is:

[0092]

[0093] The Legendre transformation is converted to the classical mechanics Hamiltonian:

[0094]

[0095] In the embodiment of the present application, it is necessary to transform the classical mechanical variables into quantum mechanical operators through canonical quantization to achieve the characterization of the quantum bit state. Based on the transformation rule, the node flux of the Josephson junction becomes the flux operator , conjugate momentum becomes the momentum operator , and they satisfy the canonical quantum commutation formula:

[0096]

[0097] For superconducting quantum circuits, dimensionless reduction operators are generally used. The reduction operators include: reduced momentum operator ;Reduced flux operator The embodiment of the present application also needs to transform the physical quantity that is not an operator into the corresponding reduced physical quantity, specifically: transform the fixed magnetic flux into the reduced fixed magnetic flux ; Convert the time-dependent magnetic flux into the reduced time-dependent magnetic flux .

[0098] The Hamiltonian operator of the Fluxonium equivalent circuit of the embodiment of the present application is as follows:

[0099]

[0100] in, is the capacitance energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the external voltage, is the inductance energy of the equivalent circuit, is the superconducting loop inductance, is the Josephson energy of the equivalent circuit.

[0101] Expand the quadratic terms in the system's Hamiltonian operator and omit the non-operator terms:

[0102]

[0103] Where, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0104]

[0105] For charge drive, It is flux driven.

[0106] Fluxonium qubits have good anharmonicity, and their ground state and the first excited state The Hamiltonian operator of the undriven Fluxonium acts on the ground state and the first excited state On the Hilbert space of the quantum bit expanded by the basis vector, its form is:

[0107]

[0108] Among them, the Pauli matrix . is the qubit frequency, Equal to the energy difference between the first excited state and the ground state. The value needs to be calibrated through measurement in the experiment.

[0109] reduced flux operator In the Hilbert space of quantum bits, it is proportional to , the reduced momentum operator Proportional to .

[0110] The Hamiltonian operator on the Hilbert space of quantum bits is of the form:

[0111]

[0112] in, is the charge-driven Rabi oscillation frequency, and its magnitude is adjusted by The specific value is calibrated through measurement in the experiment. is the Rabi oscillation frequency driven by magnetic flux, and its magnitude is adjusted by adjusting the amplitude of the AC current source. The specific value is calibrated through measurement in the experiment. is the frequency of charge drive and flux drive. is the phase of the charge drive, is the phase difference between charge drive and flux drive. is a dimensionless envelope function.

[0113] Step 202, respectively adjust the amplitudes of the AC voltage source and the AC current source so that the Rabi oscillation frequency of the flux drive is equal to the Rabi oscillation frequency of the charge drive; set the phase difference between the charge drive and the flux drive to a first set value, adjust the drive frequency and the quantum bit frequency to meet the resonance condition; adjust the dimensionless envelope function and the phase of the charge drive and the flux drive to rotate about the rotation axis located in the first coordinate plane.

[0114] In the embodiment of the present application, by adjusting the AC voltage source The amplitude of and the amplitude of the AC current source make the Rabi oscillation frequency driven by the flux equal to the Rabi oscillation frequency driven by the charge, that is, . Make the phase difference between charge drive and flux drive , the driving frequency is equal to the quantum bit frequency, that is, . Transform the coordinate system into a rotating coordinate system, and the transformation operator is .

[0115] After completing the above settings, in the rotating coordinate system, the system Hamiltonian operator is in the form of:

[0116]

[0117] In the embodiment of the present application, the operator for obtaining this Hamiltonian does not use the rotating wave approximation. The conditions for the establishment of the rotating wave approximation are , this condition is easy to achieve in transmon superconducting qubits. But in Fluxonium superconducting qubits, the qubit frequency Small, if you want to achieve a fast rate of single-qubit gate requires Rabi frequency The error of the rotating wave approximation is significant. This embodiment of the present application does not use this approximation.

[0118] Dimensionless envelope function can be adjusted via arbitrary waveform generator and the phase of the drive The rotation operation on any rotation axis in the xy plane on the quantum bit Bloch sphere can be realized, and the rotation angle is:

[0119]

[0120] represents the angle variable that changes with time, is a dimensionless envelope function, and the polar coordinates of the rotation axis in the xy plane are .

[0121] When the initial state of the quantum bit is states, quantum gates The initial ground state Conversion to the first excited state The realization method is to adjust the rotation angle to ， as follows ：

[0122] And adjust the driving phase to 0, that is .

[0123] When the initial state of the quantum bit is states, quantum gates You can state into superposition state The realization method is to adjust the rotation angle to :

[0124]

[0125] And adjust the drive phase to ,Right now .

[0126] Step 203: Adjust the rotation axis of the first coordinate plane to different rotation angles to represent different states of the quantum bit.

[0127] The technical solutions of the embodiments of this application address the issue of low quantum gate operation speeds in fluxonium qubits. By designing a circuit structure for single-qubit gates that does not utilize rotating wave approximation, even high-speed single-qubit gates are protected from errors caused by the failure of the rotating wave approximation. Due to the high anharmonicity of fluxonium, the qubit gate state control methods of the embodiments of this application enable superconducting qubits to achieve both low leakage error rates and fast single-qubit gate operations.

[0128] Figure 4 FIG. 1 shows a schematic diagram of the structure of a state adjustment device based on a single quantum bit gate according to an embodiment of the present application. Figure 4 As shown, the state adjustment device based on a single quantum bit gate in an embodiment of the present application includes:

[0129] A driving unit 40 is used to perform charge driving and flux driving on the superconducting quantum bit Fluxonium equivalent circuit, wherein the charge driving is achieved by a capacitively coupled AC voltage source, and the flux driving is achieved by induction of an AC current source;

[0130] an adjustment unit 41 for adjusting the amplitudes of the AC voltage source and the AC current source, respectively, so that the Rabi oscillation frequency of the flux drive is equal to the Rabi oscillation frequency of the charge drive; setting the phase difference between the charge drive and the flux drive to a first set value, adjusting the drive frequency and the qubit frequency to meet the resonance condition; and adjusting the dimensionless envelope function and the phases of the charge drive and the flux drive to rotate about the rotation axis located in the first coordinate plane;

[0131] The state characterization unit 42 is configured to characterize different states of the quantum bit by adjusting the rotation axis of the first coordinate plane to different rotation angles.

[0132] The dimensionless reduction operators in the embodiments of the present application include:

[0133] Reduced momentum operator ;Reduced flux operator ;

[0134] And, the fixed flux is transformed into the reduced fixed flux, which is: ; Convert the time-dependent magnetic flux into the reduced time-dependent magnetic flux, which is: ;

[0135] The Hamiltonian operator is:

[0136]

[0137] in, is the capacitance energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the external voltage, is the inductance energy of the equivalent circuit, is the superconducting loop inductance, is the Josephson energy of the equivalent circuit.

[0138] exist Figure 4 Based on the structure shown, the state adjustment device based on the single-qubit gate of the present application may further include:

[0139] Transformation Unit ( Figure 4 ), which is used to adaptively transform the Hamiltonian operator, that is, to expand the quadratic terms of the Hamiltonian operator and omit the non-operator terms, as follows:

[0140]

[0141] Where, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0142]

[0143] For charge drive, It is driven by magnetic flux;

[0144] Apply the Hamiltonian operator of the undriven Fluxonium to the ground state and the first excited state On the Hilbert space of the quantum bit expanded by the basis vector, its form is:

[0145]

[0146] Among them, the Pauli matrix ; is the qubit frequency, Equal to the energy difference between the first excited state and the ground state;

[0147] reduced flux operator In the Hilbert space of quantum bits, it is proportional to , the reduced momentum operator Proportional to ;

[0148] The Hamiltonian operator on the Hilbert space of quantum bits is of the form:

[0149]

[0150] in, is the charge-driven Rabi oscillation frequency, is the flux-driven Rabi oscillation frequency, are the frequencies of charge drive and flux drive, is the phase of the charge drive, is the phase difference between charge drive and flux drive; is a dimensionless envelope function.

[0151] In some optional embodiments, the rotation angle of the rotation axis is determined by the following integral relationship:

[0152]

[0153] The polar coordinates of the rotation axis in the first coordinate plane are (cosφ, -sinφ).

[0154] In some optional implementations, the state representation unit 42 is further configured to:

[0155] Based on quantum gates , adjust the rotation angle of the rotating axis by using the arbitrary waveform generator, and change the initial base state Conversion to the first excited state ,as follows ：

[0156] And adjust the drive phase to 0;

[0157] Based on quantum gates , adjust the rotation angle of the rotating axis through the arbitrary waveform generator, state into superposition state ,as follows:

[0158]

[0159] And adjust the drive phase to .

[0160] In an exemplary embodiment, each processing unit in the state adjustment device based on a single quantum bit gate in the embodiment of the present application can be implemented by one or more central processing units (CPU), graphics processing units (GPU), application-specific integrated circuits (ASIC), DSP, programmable logic devices (PLD), complex programmable logic devices (CPLD), field-programmable gate arrays (FPGA), general-purpose processors, controllers, microcontrollers (MCU), microprocessors, or other electronic components.

[0161] Regarding the device in the above embodiment, the specific manner in which each module and unit performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0162] According to an embodiment of the present application, the present application also describes an electronic device and a readable storage medium.

[0163] Figure 5 A schematic block diagram of an example electronic device 800 that can be used to implement an embodiment of the present application is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital assistants, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present application described and / or claimed herein.

[0164] like Figure 5As shown, device 800 includes a computing unit 801, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 802 or a computer program loaded from a storage unit 808 into a random access memory (RAM) 803. RAM 803 may also store various programs and data required for the operation of device 800. Computing unit 801, ROM 802, and RAM 803 are interconnected via a bus 804. An input / output (I / O) interface 805 is also connected to bus 804.

[0165] Various components in device 800 are connected to I / O interface 805, including an input unit 806, such as a keyboard, mouse, etc.; an output unit 807, such as various types of displays, speakers, etc.; a storage unit 808, such as a magnetic disk, optical disk, etc.; and a communication unit 809, such as a network card, modem, wireless communication transceiver, etc. The communication unit 809 allows device 800 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0166] Computing unit 801 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Computing unit 801 performs the various methods and processes described above, such as the state adjustment method based on a single-qubit gate. For example, in some embodiments, the state adjustment method based on a single-qubit gate can be implemented as a computer software program tangibly embodied in a machine-readable medium, such as storage unit 808. In some embodiments, part or all of the computer program can be loaded and / or installed onto device 800 via ROM 802 and / or communication unit 809. When the computer program is loaded into RAM 803 and executed by computing unit 801, one or more steps of the state adjustment method based on a single-qubit gate described above can be performed. Alternatively, in other embodiments, the computing unit 801 may be configured to execute a state adjustment method based on a single-qubit gate in any other appropriate manner (for example, by means of firmware).

[0167] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on a chip (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0168] The program code for implementing the methods of the present application can be written in any combination of one or more programming languages. Such program code can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the program code is executed by the processor or controller, the functions / operations specified in the flow charts and / or block diagrams are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0169] In the context of this application, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or apparatus. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of machine-readable storage media may include an electrical connection based on one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), optical fibers, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0170] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0171] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include a local area network (LAN), a wide area network (WAN), and the Internet.

[0172] A computer system may include a client and a server. The client and server are generally remote from each other and typically interact through a communication network. The client-server relationship arises through computer programs running on the respective computers and having a client-server relationship with each other. The server may be a cloud server, a server in a distributed system, or a server integrated with a blockchain.

[0173] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this application can be achieved. This is not a limitation herein.

[0174] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0175] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A state adjustment method based on a single-qubit gate, characterized in that: The method comprises: The superconducting quantum bit Fluxonium equivalent circuit is charged and flux driven, where the charge drive is achieved through a capacitively coupled AC voltage source, and the flux drive is achieved through the induction of an AC current source; Adjust the amplitudes of the AC voltage source and the AC current source respectively to make the Rabi oscillation frequency of the flux drive equal to the Rabi oscillation frequency of the charge drive; set the phase difference between the charge drive and the flux drive to , adjust the driving frequency to be equal to the quantum bit frequency, that is , to meet the resonance condition; adjusting the dimensionless envelope function, and the phase of the charge drive and the flux drive to achieve a rotation operation on the rotation axis located in the first coordinate plane; By adjusting the rotation axis of the first coordinate plane to different rotation angles, different states of the quantum bit can be represented.

2. The method according to claim 1, characterized in that Dimensionless reduction operators include: Reduced momentum operator ;Reduced flux operator ,in, is the basic charge, is the charge operator, which is the charge of the Cooper pair, represents the magnetic flux quantum, which is a constant; And, the fixed flux Transformed into reduced fixed flux ,for: ; The time-dependent magnetic flux Transformed into reduced time-dependent magnetic flux ,for: ; The Hamiltonian operator is: in, is the capacitance energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the external voltage, is the inductance energy of the equivalent circuit, is the superconducting loop inductance, is the Josephson energy of the equivalent circuit.

3. The method according to claim 2, characterized in that The method further comprises: The Hamiltonian operator is adaptively transformed, that is, the quadratic term of the Hamiltonian operator is expanded and the non-operator term is omitted, as follows: Where, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows: For charge drive, It is driven by magnetic flux; Apply the Hamiltonian operator of the undriven Fluxonium to the ground state and the first excited state On the Hilbert space of the quantum bit expanded by the basis vector, its form is: Among them, the Pauli matrix ; is the qubit frequency, Equal to the energy difference between the first excited state and the ground state; reduced flux operator In the Hilbert space of quantum bits, it is proportional to , the reduced momentum operator Proportional to ; The Hamiltonian operator on the Hilbert space of quantum bits is of the form: in, is the charge-driven Rabi oscillation frequency, is the flux-driven Rabi oscillation frequency, are the frequencies of charge drive and flux drive, is the phase of the charge drive, is the phase difference between charge drive and flux drive; is a dimensionless envelope function.

4. The method according to claim 3, characterized in that The rotation angle of the rotation axis is determined by the following integral relationship: represents the angle variable that changes with time, is the Rabi frequency, is a dimensionless envelope function, and the polar coordinates of the rotation axis in the first coordinate plane are (cosφ, -sinφ).

5. The method according to claim 4, characterized in that The adjusting the rotation axis of the first coordinate plane to different rotation angles to represent different states of the quantum bit includes: Based on quantum gates , adjust the rotation angle of the rotating axis by using the arbitrary waveform generator, and change the initial base state Conversion to the first excited state ,as follows ： And adjust the drive phase to 0; Based on quantum gates , adjust the rotation angle of the rotating axis through the arbitrary waveform generator, state into superposition state ,as follows: And adjust the drive phase to .

6. A state adjustment device based on a single-qubit gate, characterized in that: The device comprises: A driving unit, used to perform charge driving and flux driving on the superconducting quantum bit Fluxonium equivalent circuit, wherein the charge driving is achieved by a capacitively coupled AC voltage source, and the flux driving is achieved by induction of an AC current source; The adjustment unit is used to adjust the amplitude of the AC voltage source and the AC current source respectively so that the Rabi oscillation frequency of the flux drive is equal to the Rabi oscillation frequency of the charge drive; the phase difference between the charge drive and the flux drive is set to , adjust the driving frequency to be equal to the quantum bit frequency, that is , to meet the resonance condition; adjusting the dimensionless envelope function, and the phase of the charge drive and the flux drive to achieve a rotation operation on the rotation axis located in the first coordinate plane; The state characterization unit is used to characterize different states of the quantum bit by adjusting the rotation axis of the first coordinate plane to different rotation angles.

7. The device according to claim 6, characterized in that Dimensionless reduction operators include: Reduced momentum operator ;Reduced flux operator ,in, is the basic charge, is the charge operator, which is the charge of the Cooper pair, represents the magnetic flux quantum, which is a constant; And, the fixed flux Transformed into reduced fixed flux ,for: ; The time-dependent magnetic flux Transformed into reduced time-dependent magnetic flux ,for: ; The Hamiltonian operator is: in, is the capacitance energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the external voltage, is the inductance energy of the equivalent circuit, is the superconducting loop inductance, is the Josephson energy of the equivalent circuit.

8. The device according to claim 7, characterized in that The device further comprises: The transformation unit is used to adaptively transform the Hamiltonian operator, that is, to expand the quadratic terms of the Hamiltonian operator and omit the non-operator terms, as follows: Where, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows: For charge drive, It is driven by magnetic flux; Apply the Hamiltonian operator of the undriven Fluxonium to the ground state and the first excited state On the Hilbert space of the quantum bit expanded by the basis vector, its form is: Among them, the Pauli matrix ; is the qubit frequency, Equal to the energy difference between the first excited state and the ground state; reduced flux operator In the Hilbert space of quantum bits, it is proportional to , the reduced momentum operator Proportional to ; The Hamiltonian operator on the Hilbert space of quantum bits is of the form: in, is the charge-driven Rabi oscillation frequency, is the flux-driven Rabi oscillation frequency, are the frequencies of charge drive and flux drive, is the phase of the charge drive, is the phase difference between charge drive and flux drive; is a dimensionless envelope function.

9. The device according to claim 8, characterized in that The rotation angle of the rotation axis is determined by the following integral relationship: represents the angle variable that changes with time, is the Rabi frequency, is a dimensionless envelope function, and the polar coordinates of the rotation axis in the first coordinate plane are (cosφ, -sinφ).

10. The device according to claim 9, characterized in that The state representation unit is further configured to: Based on quantum gates , adjust the rotation angle of the rotating axis by using the arbitrary waveform generator, and change the initial base state Conversion to the first excited state ,as follows ： And adjust the drive phase to 0; Based on quantum gates , adjust the rotation angle of the rotating axis through the arbitrary waveform generator, state into superposition state ,as follows: And adjust the drive phase to .

11. An electronic device, characterized in that: include: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the steps of the state adjustment method based on the single-qubit gate according to any one of claims 1 to 5.

12. A non-transitory computer-readable storage medium storing computer instructions, characterized in that: The computer instructions are used to enable the computer to execute the steps of the state adjustment method based on a single-qubit gate according to any one of claims 1 to 5.

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