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

Abstract

The invention discloses a state adjustment method and device based on a single quantum bit gate, electronic equipment and a storage medium, and relates to the state control technology of the quantum bit gate, and the method comprises the steps: carrying out the charge driving and magnetic flux driving of a superconducting quantum bit Fluxium equivalent circuit; the amplitudes of the AC voltage source and the AC current source are respectively adjusted, so that the Robis oscillation frequency driven by the electromagnetic flux is equal to the Robis oscillation frequency driven by the charge; adjusting the driving frequency and the quantum bit frequency to meet a resonance condition; adjusting the phases of the dimensionless envelope function and the charge drive and the flux drive for rotation of an axis of rotation located in a first coordinate plane; and adjusting the rotating shaft to be at different rotating angles so as to represent different states of the quantum bits. According to the invention, the superconducting quantum bit can have a low leakage error rate, and can also have rapid single quantum gate operation.

Description

Technical Field

[0001] This application relates to the state control technology of quantum bit gates, and particularly to a method, device, electronic device and storage medium for adjusting the state based on single quantum bit gates. Background Art

[0002] The most widely used superconducting quantum bit at present is Transmon, which has a relatively high quantum bit frequency, a relatively fast bit gate operation rate, and a relatively simple structure, thus facilitating the design and integration of quantum circuits. A single quantum bit gate with high precision usually requires that the quantum bit frequency is much greater than the Rabi oscillation frequency, because the rotating wave approximation is used in the theory of single quantum bit gate operations, and the condition for the establishment of this approximation is that the quantum bit frequency is much greater than the Rabi oscillation frequency. The Transmon superconducting quantum bit has a relatively large quantum bit frequency. Through the charge drive formed by capacitively coupling a voltage source, the Transmon superconducting quantum bit can accurately implement single quantum bit gate operations through the rotating wave approximation. Summary of the Invention

[0003] This application provides a method, device, electronic device and storage medium for adjusting the state based on single quantum bit gates, so as to solve at least the above technical problems existing in the prior art.

[0004] According to the first aspect of this application, a method for adjusting the state based on single quantum bit gates is provided, including: Performing charge drive and flux drive on the Fluxonium equivalent circuit of the superconducting quantum bit, wherein the charge drive is realized through an AC voltage source coupled by a capacitor, and the flux drive is induced through an AC current source; Respectively adjusting the amplitudes of the AC voltage source and the AC current source to make the Rabi oscillation frequency of the magnetic flux drive 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, and adjusting the drive frequency and the quantum bit frequency to meet the resonance condition; adjusting the dimensionless envelope function and the phases of the charge drive and the flux drive to rotate around the rotation axis in the first coordinate plane; By adjusting the rotation axis in the first coordinate plane to be in different rotation angles, different states of the quantum bit are characterized.

[0005] In some optional embodiments, the dimensionless reduced operator includes: Reduced momentum operator ; reduced flux operator , where is the elementary charge quantity, is the charge operator, which is the charge of Cooper pairs, represents the magnetic flux quantum and is a constant; And, the fixed magnetic flux is transformed into a reduced fixed magnetic flux , which is: ; The time-dependent magnetic flux is transformed into a reduced time-dependent magnetic flux , which is: ; The Hamiltonian operator is:

[0006] where is the capacitive energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the applied voltage, is the inductive energy of the equivalent circuit, is the inductance of the superconducting loop, is the Josephson energy of the equivalent circuit.

[0007] In some alternative embodiments, the method further includes: Performing an adaptive transformation on the Hamiltonian operator, that is, expanding the quadratic terms of the Hamiltonian operator and omitting the non-operator terms, as follows:

[0008] In the formula, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0009] is the charge drive, is the flux drive; Acting the Hamiltonian operator of the undriven Fluxonium on the Hilbert space of the qubit expanded with the ground state and the first excited state as the basis vectors, its form is:

[0010] where the Pauli matrix ; is the qubit frequency, is equal to the energy difference between the first excited state and the ground state; The reduced magnetic flux operator is proportional to on the Hilbert space of the qubit, and the reduced momentum operator is proportional to ; The form of the Hamiltonian operator on the Hilbert space of the qubit is:

[0011] Among them, is the Rabi oscillation frequency driven by charge, is the Rabi oscillation frequency driven by magnetic flux, is the frequency of charge drive and magnetic flux drive, is the phase of charge drive, is the phase difference between charge drive and magnetic flux drive; is a dimensionless envelope function.

[0012] In some alternative embodiments, the rotation angle of the rotation axis is determined by the following integral relationship:

[0013] represents an 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).

[0014] In some alternative embodiments, by adjusting the rotation axis of the first coordinate plane to different rotation angles to characterize different states of the qubit, including: Based on the quantum gate , the rotation angle of the rotation axis is adjusted by an arbitrary waveform generator to convert the initial ground state to the first excited state , as follows ：

[0015] and adjust the drive phase to 0; Based on the quantum gate , the rotation angle of the rotation axis is adjusted by an arbitrary waveform generator to convert state to the superposition state , as follows:

[0016] and adjust the drive phase to .

[0017] According to the second aspect of the present application, there is provided a state adjustment device based on a single qubit gate, including: A driving unit for performing charge drive and magnetic flux drive on the Fluxonium equivalent circuit of the superconducting qubit, wherein the charge drive is realized by an AC voltage source coupled by a capacitor, and the magnetic flux drive is induced by an AC current source; Adjustment unit, configured to adjust the amplitudes of the AC voltage source and the AC current source respectively, so that the Rabi oscillation frequency driven by the magnetic flux is equal to the Rabi oscillation frequency driven by the charge; set the phase difference between the charge drive and the magnetic flux drive to a first set value, and adjust the drive frequency and the qubit frequency to meet the resonance condition; adjust the dimensionless envelope function, as well as the phases of the charge drive and the magnetic flux drive, to rotate about the rotation axis in the first coordinate plane; State characterization unit, configured to characterize different states of the qubit by adjusting the rotation axis in the first coordinate plane to be at different rotation angles.

[0018] In some alternative embodiments, the dimensionless reduced operator includes: Reduced momentum operator ; reduced magnetic flux operator , where is the elementary charge, is the charge operator, which is the charge of a Cooper pair, is the magnetic flux quantum, which is a constant; And, transforming the fixed magnetic flux into the reduced fixed magnetic flux is: ; transforming the time-dependent magnetic flux into the reduced time-dependent magnetic flux is: ; The Hamiltonian operator is:

[0019] where is the capacitive energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the applied voltage, is the inductive energy of the equivalent circuit, is the inductance of the superconducting loop, is the Josephson energy of the equivalent circuit.

[0020] In some alternative embodiments, the device further includes: Transformation unit, configured to perform an adaptive transformation on the Hamiltonian operator, that is, expand the quadratic terms of the Hamiltonian operator and omit the non-operator terms, as follows:

[0021] In the formula, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0022] is the charge drive, It is flux-driven; Act on the Hamiltonian operator of the undriven Fluxonium on the Hilbert space of the qubit expanded in terms of the ground state and the first excited state as the basis vectors, and its form is:

[0023] where the Pauli matrix ; is the qubit frequency, which is equal to the energy difference between the first excited state and the ground state; the reduced flux operator is proportional to on the Hilbert space of the qubit, and the reduced momentum operator is proportional to ; The form of the Hamiltonian operator on the Hilbert space of the qubit is:

[0024] where is the Rabi oscillation frequency of the charge drive, is the Rabi oscillation frequency of the flux drive, is the frequency of the charge drive and the flux drive, is the phase of the charge drive, is the phase difference between the charge drive and the flux drive; is the dimensionless envelope function.

[0025] In some alternative embodiments, the rotation angle of the rotation axis is determined by the following integral relationship:

[0026] represents the time-varying angular variable, is the Rabi frequency, is the dimensionless envelope function, and the polar coordinates of the rotation axis in the first coordinate plane are (cosφ, -sinφ).

[0027] In some alternative embodiments, the state characterization unit is further configured to: Based on the quantum gate , adjust the rotation angle of the rotation axis through an arbitrary waveform generator, and convert the initial ground state to the first excited state , as follows ：

[0028] and adjust the drive phase to 0; Based on the quantum gate Adjust the rotation angle of the rotating shaft through an arbitrary waveform generator to convert the state to a superposition state as follows:

[0029] and adjust the driving phase to .

[0030] According to the third aspect of the present application, an electronic device is provided, including: at least one processor; and a memory communicatively connected to the at least one processor; wherein, the memory stores instructions executable 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 execute the steps of the method for adjusting the state based on a single qubit gate according to the present application.

[0031] According to the fourth aspect of the present application, a non-transitory computer-readable storage medium storing computer instructions is provided, and the computer instructions are used to cause the computer to execute the steps of the method for adjusting the state based on a single qubit gate according to the present application.

[0032] The method, device, equipment and storage medium for adjusting the state based on a single qubit gate according to the present application adjust the state of the single qubit gate by controlling the rotating shaft in the first coordinate plane of the Fluxonium equivalent circuit, so as to represent different quantum information indications. Thus, even if the speed of the single qubit gate is very fast, it will not cause errors caused by the failure of the rotating wave approximation. The technical solution of the present application has the advantage of high anharmonicity, enabling the superconducting qubit to have both a low leakage error rate and fast single qubit gate operations.

[0033] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used 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

[0034] By referring to the drawings and reading the following detailed description, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the drawings, several embodiments of the present application are shown in an exemplary rather than restrictive manner, where: In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0035] Figure 1 shows a schematic diagram of the equivalent circuit of Fluxonium according to an embodiment of the present application; Figure 2 The flowchart of the state adjustment method based on single qubit gates according to the embodiments of the present application is shown; Figure 3 The driving schematic diagram of the equivalent circuit Fluxonium of the Fluxonium according to the embodiments of the present application is shown; Figure 4 The composition structure schematic diagram of the state adjustment device based on single qubit gates according to the embodiments of the present application is shown; Figure 5 The composition structure schematic diagram of an electronic device according to an embodiment of the present application is shown. Detailed implementation manners

[0036] To make the objectives, features, and advantages of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0037] Quantum computing is a computing paradigm based on the principles of quantum mechanics. Different from the classical bits 0 and 1 in classical computing, quantum computing uses qubits states and states. states and states are two mutually orthogonal vectors, which expand into a two-dimensional Hilbert space. A qubit can be in any vector in this space, such as the superposition state . Physically, two energy eigenstates with different energies of a physical system are generally used to represent states and states.

[0038] Superconducting quantum computing is a mainstream technical route for realizing quantum computing, which uses superconducting materials and quantum circuits to implement qubits. The most important physical device is the superconducting Josephson junction, which can make the superconducting circuit generate a non-harmonic energy level structure, which is different from the equally spaced energy level structure formed by the harmonic oscillation of the oscillating (LC) circuit. The main advantages of superconducting quantum circuits are strong scalability and fast qubit gate operations. Fast qubit gate operations are very important because a large number of quantum gate operations are required for large-scale quantum computing, and fast gate response can significantly shorten the time of quantum computing. The states and states of superconducting qubits usually correspond to the ground state and the first excited state, and the energy level difference corresponds to the qubit frequency. The implementation of a single qubit gate usually requires applying a microwave pulse to the qubit to achieve State sum The Rabi oscillation between states, and the higher the frequency of the Rabi oscillation, the faster the rate of the qubit gate.

[0039] The embodiment of the present application adopts a superconducting qubit Fluxonium single qubit gate and uses it to control different states of the qubit. Figure 1 The equivalent circuit schematic diagram of Fluxonium in the embodiment of the present application is shown. As Figure 1 shown, the Fluxonium superconducting qubit is composed of a superconducting Josephson junction and a superconducting inductor in parallel. Among them, the superconducting inductor is composed of many superconducting Josephson junctions in series, and its equivalent circuit element is an inductor. As Figure 1 shown, the equivalent circuit of Fluxonium is composed of a capacitor , a Josephson junction (the Josephson energy is ), and an inductor L in parallel, with one end grounded. A fixed magnetic flux passes through the Josephson junction and the inductor loop, and this fixed magnetic flux is induced by a DC current source. This magnetic flux is set to , called the "sweet spot", and such a setting can make the qubit least sensitive to magnetic flux noise. The dynamic variable of the circuit is the node magnetic flux .

[0040] Figure 2 The flow schematic diagram of the state adjustment method based on the single qubit gate in the embodiment of the present application is shown. As Figure 2 shown, the state adjustment method based on the single qubit gate in the embodiment of the present application includes the following processing steps: Step 201, perform charge drive and magnetic flux drive on the equivalent circuit of the superconducting qubit Fluxonium.

[0041] In the embodiment of the present application, the charge drive is realized by an AC voltage source through capacitive coupling, and the magnetic flux drive is induced by an AC current source. Specifically, charge drive and magnetic flux drive can be applied to the Fluxonium equivalent circuit. As Figure 3 shown, the Fluxonium superconducting qubit applies charge drive through a capacitive coupling alternating voltage source and magnetic flux drive through an alternating current source. Specifically, an alternating voltage source V(t) is connected above the qubit through a capacitor , and the fixed magnetic flux passing through the Josephson junction and the inductor loop becomes . Among them, is the time-dependent magnetic flux, which is induced by an AC current source.

[0042] According to classical circuit theory, the Lagrangian of the Fluxonium equivalent circuit in the embodiment of the present application is:

[0043] The conjugate momentum of the Josephson junction node magnetic flux is:

[0044] Through the Legendre transformation, it becomes the Hamiltonian of classical mechanics:

[0045] In the embodiments of the present application, it is necessary to transform the classical mechanics variables into quantum mechanics operators through canonical quantization to realize the representation of the quantum bit state. Based on the transformation rules, the node magnetic flux of the Josephson junction becomes the magnetic flux operator , and the conjugate momentum becomes the momentum operator , and they satisfy the canonical quantum commutation relation:

[0046] For superconducting quantum circuits, dimensionless reduced operators are generally used. The reduced operators respectively include: the reduced momentum operator ; the reduced magnetic flux operator . In the embodiments of the present application, it is also necessary to transform the physical quantities that are not operators into the corresponding reduced physical quantities, specifically: transforming the fixed magnetic flux into the reduced fixed magnetic flux ; transforming the time-dependent magnetic flux into the reduced time-dependent magnetic flux .

[0047] The Hamiltonian operator of the Fluxonium equivalent circuit in the embodiments of the present application is as follows:

[0048] Among them, is the capacitive energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the applied voltage, is the inductive energy of the equivalent circuit, is the inductance of the superconducting loop, is the Josephson energy of the equivalent circuit.

[0049] Expand the quadratic term in the system Hamiltonian operator and omit the non-operator terms:

[0050] In the formula, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0051] Charge-driven, Flux-driven.

[0052] The fluxonium qubit has good anharmonicity, and its ground state and the first excited state . The Hamiltonian operator of the undriven fluxonium acts on the Hilbert space of the qubit expanded in terms of the ground state and the first excited state as the basis vectors, and its form is:

[0053] where the Pauli matrix . is the qubit frequency, which is equal to the energy difference between the first excited state and the ground state. The value of

[0054] The reduced flux operator is proportional to on the Hilbert space of the qubit, and the reduced momentum operator is proportional to .

[0055] The form of the Hamiltonian operator on the Hilbert space of the qubit is:

[0056] where is the Rabi oscillation frequency of the charge drive, and its magnitude is adjusted by adjusting the amplitude, and the specific value is calibrated by measurement in the experiment. is the Rabi oscillation frequency of the flux drive, and its magnitude is adjusted by adjusting the amplitude of the AC current source, and the specific value is calibrated by measurement in the experiment. is the frequency of the charge drive and the flux drive. is the phase of the charge drive, is the phase difference between the charge drive and the flux drive. is the dimensionless envelope function.

[0057] Step 202: 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 the first set value, and adjust the drive frequency and the qubit frequency to meet the resonance condition; adjust the dimensionless envelope function, as well as the phases of the charge drive and the flux drive, to rotate around the rotation axis in the first coordinate plane.

[0058] In the embodiments of the present application, by adjusting the AC voltage source The amplitudes of the [amplitude] and the AC current source are such that the Rabi oscillation frequency driven by magnetic flux and the Rabi oscillation frequency driven by charge are equal, i.e., Make the phase difference between charge drive and flux drive , and the drive frequency is equal to the qubit frequency, i.e., . Transform the coordinate system to a rotating coordinate system, and the transformation operator is .

[0059] After completing the above settings, in the rotating coordinate system, the form of the system Hamiltonian operator is:

[0060] In the embodiments of the present application, the operator for obtaining this Hamiltonian does not use the rotating wave approximation. The condition for the validity of the rotating wave approximation is , and this condition is easily achieved in transmon superconducting qubits. However, in Fluxonium superconducting qubits, the qubit frequency is relatively small. If a fast single-qubit gate is desired, a large Rabi frequency is required, and the error of the rotating wave approximation is significant. The embodiments of the present application do not use this approximation.

[0061] By an arbitrary waveform generator, the dimensionless envelope function and the drive phase can be adjusted to achieve a rotation operation on any rotation axis located in the xy plane on the Bloch sphere of the qubit. The rotation angle is:

[0062] represents the time-varying angular variable, is the dimensionless envelope function, and the polar coordinates of the rotation axis in the xy plane are .

[0063] When the initial state of the qubit is state, the quantum gate can convert the initial ground state to the first excited state . The implementation method is to adjust the rotation angle to ， as follows ：

[0064] and adjust the drive phase to 0, i.e., .

[0065] When the initial state of the qubit is state, the quantum gate can Convert the state to a superposition state . The implementation method is to adjust the rotation angle to :

[0066] and adjust the driving phase to , that is .

[0067] Step 203: Characterize different states of the qubit by adjusting the rotation axis of the first coordinate plane to different rotation angles.

[0068] The technical solution of the embodiment of the present application solves the problem of the low operation rate of the quantum gate of the Fluxonium qubit. By designing the circuit structure of the single-qubit gate without using the rotating wave approximation, even if the speed of the single-qubit gate is very fast, it will not cause errors caused by the failure of the rotating wave approximation. Due to the high anharmonicity of Fluxonium, the qubit gate state control method of the embodiment of the present application can enable the superconducting qubit to have both a low leakage error rate and a fast single-qubit gate operation.

[0069] Figure 4 shows the schematic composition structure of the state adjustment device based on the single-qubit gate of the embodiment of the present application. As Figure 4 shown, the state adjustment device based on the single-qubit gate of the embodiment of the present application includes: The driving unit 40 is used to perform charge driving and flux driving on the equivalent circuit of the superconducting qubit Fluxonium, where the charge driving is realized by an AC voltage source with capacitive coupling, and the flux driving is realized by inducing an AC current source; The adjustment unit 41 is used to adjust the amplitudes of the AC voltage source and the AC current source respectively, so that the Rabi oscillation frequency of the magnetic flux driving is equal to the Rabi oscillation frequency of the charge driving; set the phase difference between the charge driving and the flux driving to a first set value, adjust the driving frequency and the qubit frequency to meet the resonance condition; adjust the dimensionless envelope function, as well as the phases of the charge driving and the flux driving, to rotate around the rotation axis of the first coordinate plane; The state characterization unit 42 is used to characterize different states of the qubit by adjusting the rotation axis of the first coordinate plane to different rotation angles.

[0070] The dimensionless reduced operators in the embodiment of the present application include: Reduced momentum operator ; Reduced flux operator ; And, converting the fixed flux to the reduced fixed flux is: ; The time-dependent magnetic flux is transformed into a reduced time-dependent magnetic flux, which is: ; The Hamiltonian operator is:

[0071] where is the capacitive energy of the equivalent circuit, is the total capacitance of the equivalent circuit, is the applied voltage, is the inductive energy of the equivalent circuit, is the inductance of the superconducting loop, is the Josephson energy of the equivalent circuit.

[0072] Based on the structure shown in Figure 4 , the state adjustment device of the present application based on a single qubit gate may further include: A transformation unit ( Figure 4 , not shown in the figure), which is used to perform an adaptive transformation on the Hamiltonian operator, that is, expand the quadratic term of the Hamiltonian operator and omit the non-operator terms, as follows:

[0073] In the formula, the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows:

[0074] is the charge drive, is the flux drive; The Hamiltonian operator of the undriven Fluxonium acts on the Hilbert space of the qubit expanded with the ground state and the first excited state as the basis vectors, and its form is:

[0075] where the Pauli matrix ; is the qubit frequency, is equal to the energy difference between the first excited state and the ground state; The reduced flux operator is proportional to on the Hilbert space of the qubit, and the reduced momentum operator is proportional to ; The form of the Hamiltonian operator on the Hilbert space of the qubit is:

[0076] where is the Rabi oscillation frequency driven by charge, is the Rabi oscillation frequency driven by magnetic flux, is the frequency of charge drive and magnetic flux drive, is the phase of charge drive, is the phase difference between charge drive and magnetic flux drive; is the dimensionless envelope function.

[0077] In some alternative embodiments, the rotation angle of the rotation axis is determined by the following integral relationship:

[0078] The polar coordinates of the rotation axis in the first coordinate plane are (cosφ, -sinφ).

[0079] In some alternative embodiments, the state characterization unit 42 is further configured to: Based on the quantum gate , adjust the rotation angle of the rotation axis through an arbitrary waveform generator, and convert the initial ground state to the first excited state , as follows ：

[0080] and adjust the drive phase to 0; Based on the quantum gate , adjust the rotation angle of the rotation axis through an arbitrary waveform generator, and convert the state to the superposition state , as follows:

[0081] and adjust the drive phase to .

[0082] In an exemplary embodiment, each processing unit in the state adjustment device based on single qubit gates according to the embodiments of the present application can be implemented by one or more central processing units (CPUs, Central Processing Unit), graphics processing units (GPUs, Graphics Processing Unit), application specific integrated circuits (ASICs, Application Specific Integrated Circuit), DSPs, programmable logic devices (PLDs, Programmable Logic Device), complex programmable logic devices (CPLDs, Complex Programmable Logic Device), field programmable gate arrays (FPGAs, Field-Programmable Gate Array), general purpose processors, controllers, microcontroller units (MCUs, MicroController Unit), microprocessors (Microprocessor), or other electronic components.

[0083] Regarding the device in the above embodiment, the specific manner in which each module and unit perform operations has been described in detail in the embodiment related to the method, and will not be elaborated here.

[0084] According to the embodiments of the present application, the present application also records an electronic device and a readable storage medium.

[0085] Figure 5 FIG. shows a schematic block diagram of an exemplary electronic device 800 that can be used to implement the embodiments of the present application. 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 processing, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely exemplary and are not intended to limit the implementation of the present application described and / or claimed herein.

[0086] As 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. In the RAM 803, various programs and data required for the operation of the device 800 can also be stored. The computing unit 801, the ROM 802, and the RAM 803 are connected to each other via a bus 804. An input / output (I / O) interface 805 is also connected to the bus 804.

[0087] Multiple components in the device 800 are connected to the I / O interface 805, including: an input unit 806, such as a keyboard, a mouse, etc.; an output unit 807, such as various types of displays, speakers, etc.; a storage unit 808, such as a magnetic disk, an optical disc, etc.; and a communication unit 809, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 809 allows the device 800 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0088] The computing unit 801 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The computing unit 801 executes the various methods and processes described above, such as the state adjustment method based on single-qubit gates. For example, in some embodiments, the state adjustment method based on single-qubit gates can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as the storage unit 808. In some embodiments, part or all of the computer program can be loaded and / or installed onto the device 800 via the ROM 802 and / or the communication unit 809. When the computer program is loaded into the RAM 803 and executed by the computing unit 801, one or more steps of the state adjustment method based on single-qubit gates described above can be executed. Alternatively, in other embodiments, the computing unit 801 can be configured to execute the state adjustment method based on single-qubit gates in any other appropriate manner (e.g., by means of firmware).

[0089] The various embodiments of the systems and techniques described above in this specification can be implemented in digital electronic circuitry, 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 interpretable on a programmable system including at least one programmable processor, which may be a special-purpose or general-purpose programmable processor that receives data and instructions from, and transmits data and instructions to, a storage system, at least one input device, and at least one output device.

[0090] The program code for implementing the methods of this application can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing device, such that the program codes, when executed by the processor or controller, cause the functions / operations specified in the flowchart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partly on the machine, as a stand-alone software package partly on the machine and partly on a remote machine, or entirely on the remote machine or server.

[0091] In the context of this application, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0092] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and a pointing device (e.g., a mouse or a trackball) through which the user can provide input to the computer. Other kinds 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 the input received from the user can be in any form (including acoustic input, voice input, or tactile input).

[0093] The systems and techniques described herein can be implemented in a computing system including backend components (e.g., as a data server), or a computing system including middleware components (e.g., an application server), or a computing system including frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system including any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected to each other by digital data communication in any form or medium (e.g., a communication network). Examples of communication networks include: local area network (LAN), wide area network (WAN), and the Internet.

[0094] A computer system can include a client and a server. The client and the server are generally remote from each other and typically interact through a communication network. The client - server relationship is created by computer programs running on the respective computers and having a client - server relationship with each other. The server can be a cloud server, a server of a distributed system, or a server incorporating a blockchain.

[0095] It should be understood that various forms of the processes shown above can be used, re - ordering, adding, or deleting steps. For example, the steps recited in this disclosure can be executed 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. No limitation is made herein.

[0096] In addition, 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 quantity of the indicated technical features. Thus, features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of this application, "a plurality of" means two or more unless otherwise specifically defined.

[0097] As described above, it is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims described above.

Claims

1. A state adjustment method based on a single quantum bit gate, characterized in that: The method comprises: The superconducting quantum bit Fluxonium equivalent circuit is charge driven 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; The amplitudes of the AC voltage source and the AC current source are adjusted respectively to make the Rabi oscillation frequency of the electromagnetic flux drive equal to the Rabi oscillation frequency of the charge drive; the phase difference between the charge drive and the magnetic 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 phases of the charge drive and the magnetic flux drive are adjusted to rotate the rotation axis located in the first coordinate plane; Different states of the quantum bit are represented by adjusting the rotation axis of the first coordinate plane to different rotation angles.

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 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 terms of the Hamiltonian operator are expanded and the non-operator terms are omitted, as follows: Where the operator in the brackets is the Hamiltonian operator of the undriven Fluxonium, as follows: For charge drive, It is flux driven; Apply the Hamiltonian operator of the undriven Fluxonium to the ground state and the first excited state In the Hilbert space of quantum bits expanded by basis vectors, its form is: Among them, the Pauli matrix ; is the qubit frequency, is equal to the energy difference between the first excited state and the ground state; reduced flux operator In the Hilbert space of quantum bits, , the reduced momentum operator Proportional to ; The Hamiltonian operator in the Hilbert space of quantum bits has the form: in, is the charge-driven Rabi oscillation frequency, is the flux-driven Rabi oscillation frequency, 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.

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 characterize different states of the quantum bit includes: Based on quantum gates , adjust the rotation angle of the rotating axis by using an arbitrary waveform generator to change the initial base state Transition 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 quantum bit gate, characterized in that: The device comprises: A driving unit, used for performing 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 regulating unit is used to respectively regulate the amplitude of the AC voltage source and the AC current source so that the Rabi oscillation frequency driven by the electromagnetic flux is equal to the Rabi oscillation frequency driven by the charge; set the phase difference between the charge drive and the magnetic flux drive to a first set value, and adjust the drive frequency and the quantum bit frequency to meet the resonance condition; regulate the dimensionless envelope function, and the phase of the charge drive and the magnetic flux drive to rotate 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 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 also includes: 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 flux driven; Apply the Hamiltonian operator of the undriven Fluxonium to the ground state and the first excited state In the Hilbert space of quantum bits expanded by basis vectors, its form is: Among them, the Pauli matrix ; is the qubit frequency, is equal to the energy difference between the first excited state and the ground state; reduced flux operator In the Hilbert space of quantum bits, , the reduced momentum operator Proportional to ; The Hamiltonian operator in the Hilbert space of quantum bits has the form: in, is the charge-driven Rabi oscillation frequency, is the flux-driven Rabi oscillation frequency, 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.

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 used for: Based on quantum gates , adjust the rotation angle of the rotating axis by using an arbitrary waveform generator to change the initial base state Transition 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 so that the at least one processor can perform the steps of the state adjustment method based on the single-qubit gate as described in 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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