Quantum circuit, chip structure and quantum bit state measuring method

Abstract

The embodiment of the invention discloses a quantum circuit, a chip structure and a quantum bit state measurement method, the quantum circuit comprises a quantum bit, an amplification circuit, a grounding end, a coupling end, a measurement input end and a measurement output end, and the amplification circuit comprises a capacitor module, a first linear inductor module, a second linear inductor module and a Josephson junction; one end of the capacitor module is connected with the coupling end; one end of the first linear inductor module is connected with the coupling end, and the other end of the first linear inductor module is connected with one end of the second linear inductor module; the Josephson junction is connected in parallel with two ends of the second linear inductor module; the quantum bit, the measurement input end and the measurement output end are respectively coupled with the corresponding coupling ends; according to the embodiment of the invention, quantum bit energy leakage can be reduced, the accuracy of a measurement result is improved, meanwhile, the line complexity of quantum bit measurement is reduced, and the method can be widely applied to scenes such as cloud technology, quantum computing and smart traffic.

Description

Technical Field

[0001] This application relates to the field of quantum computing technology, and particularly to a quantum circuit, a chip structure, and a method for measuring the state of a qubit. Background Art

[0002] Quantum computing is one of the popular research directions for further developing computing power. During the process of processing quantum computing tasks, the state of qubits will change, and it is necessary to measure the state of qubits. When performing measurements in related technologies, generally, the signals of qubits need to be amplified. However, qubits are prone to energy leakage problems when coupled to the outside world, reducing the accuracy of measurement results. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail in this application. This overview is not intended to limit the scope of protection of the claims.

[0004] Embodiments of this application provide a quantum circuit, a chip structure, and a method for measuring the state of a qubit, which can reduce the energy leakage of qubits, improve the accuracy of measurement results, and at the same time reduce the circuit complexity of qubit measurement.

[0005] On the one hand, embodiments of this application provide a quantum circuit, including qubits, an amplification circuit, a ground terminal, a coupling terminal, a measurement input terminal, and a measurement output terminal. The amplification circuit includes a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction;

[0006] One end of the capacitor module is connected to the coupling terminal, and the other end of the capacitor module is connected to the ground terminal;

[0007] One end of the first linear inductor module is connected to the coupling terminal, the other end of the first linear inductor module is connected to one end of the second linear inductor module, and the other end of the second linear inductor module is connected to the ground terminal;

[0008] The Josephson junction is connected in parallel across both ends of the second linear inductor module;

[0009] The qubit, the measurement input terminal, and the measurement output terminal are respectively coupled to the corresponding coupling terminal;

[0010] Wherein, the measurement input terminal is used to input a microwave signal, the measurement output terminal is used to output a voltage signal, and the voltage signal is used to indicate the state of the qubit.

[0011] Further, the number of the amplifying circuits and the number of the coupling ends are both two. The two amplifying circuits share the same Josephson junction, and the capacitor modules and the first linear inductor modules of each amplifying circuit are respectively connected to their corresponding coupling ends.

[0012] Further, the two amplifying circuits include a first amplifying circuit and a second amplifying circuit, the two coupling ends include a first coupling end and a second coupling end, and the two amplifying circuits also share the same second linear inductor module;

[0013] One end of the capacitor module in the first amplifying module is connected to the first coupling end, and the other end of the capacitor module in the first amplifying module is connected to the ground end;

[0014] One end of the capacitor module in the second amplifying module is connected to the second coupling end, and the other end of the capacitor module in the second amplifying module is connected to the ground end;

[0015] One end of the first linear inductor module in the first amplifying circuit is connected to the first coupling end, and one end of the first linear inductor module in the second amplifying circuit is connected to the second coupling end;

[0016] One end of the second linear inductor module is respectively connected to the other end of the first linear inductor module in the first amplifying circuit and the other end of the first linear inductor module in the second amplifying circuit, and the other end of the second linear inductor module is connected to the ground end.

[0017] Further, the two amplifying modules include a first amplifying module and a second amplifying module, and the two coupling ends include a first coupling end and a second coupling end;

[0018] One end of the capacitor module in the first amplifying module is connected to the first coupling end, and the other end of the capacitor module in the first amplifying module is connected to the ground end;

[0019] One end of the capacitor module in the second amplifying module is connected to the second coupling end, and the other end of the capacitor module in the second amplifying module is connected to the ground end;

[0020] One end of the first linear inductor module in the first amplifying circuit is connected to the first coupling end, the other end of the first linear inductor module in the first amplifying circuit is connected to one end of the second linear inductor module in the first amplifying circuit, and the other end of the second linear inductor module in the first amplifying circuit is connected to the ground end;

[0021] One end of the first linear inductor module in the second amplifier circuit is connected to the second coupling end, the other end of the first linear inductor module in the second amplifier circuit is connected to one end of the second linear inductor module in the second amplifier circuit, and the other end of the second linear inductor module in the second amplifier circuit is connected to the ground terminal.

[0022] Further, the quantum circuit further includes a third linear inductor module and a current input terminal for inputting current to the third linear inductor module. The third linear inductor module is mutually inductively connected to the second linear inductor module, and the third linear inductor module is connected to the current input terminal.

[0023] Further, the capacitor module includes distributed capacitors, and the amplifier circuit is fabricated using planar technology.

[0024] On the other hand, an embodiment of the present application further provides an amplification device, including an amplifier circuit, a ground terminal, and a coupling terminal. The amplifier circuit includes a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction;

[0025] One end of the capacitor module is connected to the coupling terminal, and the other end of the capacitor module is connected to the ground terminal;

[0026] One end of the first linear inductor module is connected to the coupling terminal, the other end of the first linear inductor module is connected to one end of the second linear inductor module, and the other end of the second linear inductor module is connected to the ground terminal;

[0027] The Josephson junction is connected in parallel across both ends of the second linear inductor module.

[0028] On the other hand, an embodiment of the present application further provides a chip structure, including the above-mentioned quantum circuit, or including the above-mentioned amplification device.

[0029] On the other hand, an embodiment of the present application further provides a method for measuring the state of a qubit, which is applied to a processor. The processor is connected to the measurement output terminal in the above-mentioned quantum circuit. The measurement method includes:

[0030] When a microwave signal is input to the measurement input terminal, obtain the target voltage signal output from the measurement output terminal;

[0031] Determine the target phase and the target amplitude according to the target voltage signal, and determine the target measurement point in the corresponding first coordinate space according to the target phase and the target amplitude;

[0032] Obtain a preset first sample point region and a second sample point region in the first coordinate space, where the first sample point region and the second sample point region are respectively used to indicate two different states of the qubit;

[0033] Determine the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region.

[0034] On the other hand, an embodiment of the present application further provides a measurement device for the state of a qubit, characterized in that the measurement device is connected to the measurement output end in the above-mentioned quantum circuit, and the measurement device includes:

[0035] A first acquisition module, configured to acquire a target voltage signal output by the measurement output end when a microwave signal is input to the measurement input end;

[0036] A signal processing module, configured to determine a target phase and a target amplitude according to the target voltage signal, and determine a target measurement point in a corresponding first coordinate space according to the target phase and the target amplitude;

[0037] A second acquisition module, configured to acquire a preset first sample point region and a second sample point region in the first coordinate space, where the first sample point region and the second sample point region are respectively used to indicate two different states of the qubit;

[0038] A state determination module, configured to determine the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region.

[0039] Furthermore, the measurement device further includes:

[0040] A frequency determination module, configured to determine the signal frequency of the microwave signal;

[0041] A first measurement module, configured to set the state of the qubit to a first state, and whenever a microwave signal with the signal frequency is input to the measurement input end, acquire a first sample voltage signal output by the measurement output end each time, determine a first sample measurement point corresponding to the first sample voltage signal in the first coordinate space, and obtain the first sample point region according to multiple first sample measurement points;

[0042] A second measurement module, configured to set the state of the qubit to a second state, and whenever a microwave signal with the signal frequency is input to the measurement input terminal, obtain a second sample voltage signal output each time by the measurement output terminal, determine a second sample measurement point corresponding to the second sample voltage signal in the first coordinate space, and obtain a second sample point region based on a plurality of the second sample measurement points.

[0043] Further, the above frequency determination module is specifically configured to:

[0044] Obtain curve data of the device frequency of the amplifier circuit changing with the magnetic flux of the amplifier circuit, where the curve data includes a first change curve corresponding to the first state and a second change curve corresponding to the second state, and the first change curve and the second change curve are located in the same second coordinate space;

[0045] Obtain a target frequency corresponding to an intersection point between the first change curve and the second change curve;

[0046] Determine the signal frequency of the microwave signal based on a difference between the target frequency and a preset value, or determine the signal frequency of the microwave signal within a frequency range including the target frequency.

[0047] Further, the above signal processing module is specifically configured to:

[0048] Demodulate the target voltage signal to obtain a demodulated voltage signal;

[0049] Sample the demodulated voltage signal to obtain a sampled voltage signal;

[0050] Restore the sampled voltage signal to obtain a restored voltage signal;

[0051] Determine the phase of the restored voltage signal as the target phase and determine the amplitude of the restored voltage signal as the target amplitude.

[0052] On the other hand, an embodiment of the present application further provides an electronic device, including a memory and a processor, where the memory stores a computer program, and when the processor executes the computer program, the above method for measuring the state of a qubit is implemented.

[0053] On the other hand, an embodiment of the present application further provides a computer-readable storage medium, where the storage medium stores a computer program, and when the computer program is executed by a processor, the above method for measuring the state of a qubit is implemented.

[0054] On the other hand, an embodiment of the present application also provides a computer program product, which includes a computer program stored in a computer-readable storage medium. A processor of a computer device reads the computer program from the computer-readable storage medium, and the processor executes the computer program, so that the computer device executes the method for measuring the state of a qubit as described above.

[0055] The embodiments of the present application at least include the following beneficial effects: By setting a capacitance module, a second linear inductor module, and a Josephson junction to form a resonant circuit, the amplification effect of the qubit signal is achieved. On this basis, a first linear inductor module is further set to reduce the non-linearity of the amplification circuit. While meeting the amplification requirements, the coupling between the amplification circuit and the outside world is reduced, thereby reducing the energy leakage of the qubit and improving the accuracy of the measurement result. Moreover, the amplification circuit can be directly coupled to the qubit without setting other intermediate devices, thereby reducing the circuit complexity of qubit measurement.

[0056] When measuring the state of a qubit, by determining a target phase and a target amplitude according to a target voltage signal, determining a target measurement point in a corresponding first coordinate space according to the target phase and the target amplitude, obtaining a preset first sample point region and a second sample point region in the first coordinate space, and determining the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region, the state of the qubit can be quickly determined in a coordinate matching manner based on the first sample point region and the second sample point region, thereby effectively improving the measurement efficiency of the qubit state.

[0057] Other features and advantages of the present application will be described in the subsequent description, and some of them will become obvious from the description or be understood by implementing the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The drawings are used to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solutions of the present application and do not constitute a limitation to the technical solutions of the present application.

[0059] Figure 1 FIG. is an alternative flowchart of a quantum circuit provided by an embodiment of the present application;

[0060] Figure 2 FIG. is an alternative potential energy diagram of an amplification circuit provided by an embodiment of the present application;

[0061] Figure 3 FIG. is a first alternative circuit schematic diagram of a quantum circuit provided by an embodiment of the present application;

[0062] Figure 4The second optional circuit schematic diagram of the quantum circuit provided by the embodiment of the present application;

[0063] Figure 5 The third optional circuit schematic diagram of the quantum circuit provided by the embodiment of the present application;

[0064] Figure 6 An optional structural schematic diagram of the amplification device provided by the embodiment of the present application;

[0065] Figure 7 The first optional circuit schematic diagram of the amplification device provided by the embodiment of the present application;

[0066] Figure 8 The second optional circuit schematic diagram of the amplification device provided by the embodiment of the present application;

[0067] Figure 9 The third optional circuit schematic diagram of the amplification device provided by the embodiment of the present application;

[0068] Figure 10 An optional flow schematic diagram of the method for measuring the state of a quantum bit provided by the embodiment of the present application;

[0069] Figure 11 An optional coordinate space schematic diagram of the first sample point region and the second sample point region provided by the embodiment of the present application;

[0070] Figure 12 An optional change curve schematic diagram of the device frequency and magnetic flux provided by the embodiment of the present application;

[0071] Figure 13 An optional coordinate space schematic diagram of the target frequency provided by the embodiment of the present application;

[0072] Figure 14 An optional architecture schematic diagram of the method for measuring the state of a quantum bit provided by the embodiment of the present application;

[0073] Figure 15 An optional structural schematic diagram of the device for measuring the state of a quantum bit provided by the embodiment of the present application;

[0074] Figure 16 A partial structural block diagram of the terminal provided by the embodiment of the present application;

[0075] Figure 17 A partial structural block diagram of the server provided by the embodiment of the present application. Detailed implementation manners

[0076] To make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0077] It should be noted that in each specific embodiment of the present application, when it comes to relevant processing based on data related to the characteristics of the target object, such as the target object attribute information or the set of attribute information, the permission or consent of the target object will be obtained first. Moreover, the collection, use, and processing of these data will comply with relevant laws, regulations, and standards. Among them, the target object can be a user. In addition, when the embodiments of the present application need to obtain the target object attribute information, the separate permission or separate consent of the target object will be obtained through methods such as pop-up windows or jumping to a confirmation page. After clearly obtaining the separate permission or separate consent of the target object, the necessary data related to the target object for the normal operation of the embodiments of the present application will be obtained.

[0078] To facilitate the understanding of the technical solutions provided by the embodiments of the present application, some key terms used in the embodiments of the present application will be explained here:

[0079] Cloud technology refers to a hosting technology that unifies a series of resources such as hardware, software, and networks within a wide area network or a local area network to achieve data computing, storage, processing, and sharing. Cloud technology is the general term for network technology, information technology, integration technology, management platform technology, application technology, etc. based on the cloud computing business model. It can form a resource pool, be used as needed, and is flexible and convenient. Cloud computing technology will become an important support. The background services of the technical network system require a large amount of computing and storage resources, such as video websites, picture websites, and more portal websites. With the high development and application of the Internet industry, in the future, each item may have its own identification mark and needs to be transmitted to the background system for logical processing. Data at different levels will be processed separately, and various industry data requires a powerful system background support, which can only be achieved through cloud computing.

[0080] Quantum computing: Quantum computing is a computing method designed using the principles of quantum mechanics. The biggest difference between it and traditional computing is that it uses quantum bits (qubits) instead of traditional binary bits (bits) for computing. Quantum bits have different characteristics from traditional binary bits. The most important characteristic is that they can be in multiple states simultaneously. It is precisely because quantum bits can represent two states simultaneously that they can carry more information, and with the same number of quantum bit units, more data operations can be completed than classical computing. Therefore, quantum computers greatly improve the processing speed of computers.

[0081] Quantum: In "quantum computing", a quantum refers to the smallest discrete unit used by a system for computing outputs.

[0082] Qubit: It is the basic information unit in quantum computing. The role played by a qubit in quantum computing is similar to that played by a bit in traditional computing, but their behaviors are very different. A classical bit is binary and can only store 0 or 1 bit, while a qubit can store a superposition of all possible states, that is, a superposition state of state |0> and state |1>. Therefore, the processing speed of the computer is greatly improved.

[0083] Qubit unit: The storage unit in a chip used to accommodate the qubits participating in the operation.

[0084] Superposition: As mentioned above, a qubit can represent two states simultaneously. Therefore, a qubit has two states at the same time and is a superposition of the two states. When in a superposition state, a qubit is a combination of all possible states. They will fluctuate continuously until they are observed and measured.

[0085] Collapse: A qubit is a superposition of all possible states. When observed, it is fixed to one state, and this fixation is called collapse.

[0086] Entanglement: Entanglement is the ability of qubits to correlate their measurement results with each other. When qubits are entangled with each other, they form a system and influence each other. We can use the measurement of one qubit to infer the information of other qubits. By adding and entangling more qubits in the system, a quantum computer can solve more complex problems.

[0087] Photon: The basic particle that transmits the electromagnetic interaction. For example, a qubit in the |1> state releases a photon and will become the |0> state.

[0088] Quantum computing is one of the popular research directions for further developing computing power. During the process of processing quantum computing tasks, the state of qubits will change, and it is necessary to measure the state of qubits. When related technologies perform measurements, generally, it is necessary to amplify the signals of qubits. However, qubits are prone to energy leakage problems when coupled with the outside world, reducing the accuracy of the measurement results.

[0089] Based on this, the embodiments of the present application provide a quantum circuit, a chip structure, and a method for measuring the state of qubits, which can reduce the energy leakage of qubits, improve the accuracy of the measurement results, and at the same time reduce the circuit complexity of qubit measurement.

[0090] Refer to Figure 1 , Figure 1An alternative structural schematic diagram of the quantum circuit provided by the embodiment of the present application. The quantum circuit includes a qubit 110, an amplification circuit 120, a ground terminal 130, a coupling terminal 140, a measurement input terminal 150, and a measurement output terminal 160. The amplification circuit 120 includes a capacitor module 121, a first linear inductor module 122, a second linear inductor module 123, and a Josephson junction 124;

[0091] One end of the capacitor module 121 is connected to the coupling terminal 140, and the other end of the capacitor module 121 is connected to the ground terminal 130;

[0092] One end of the first linear inductor module 122 is connected to the coupling terminal 140, the other end of the first linear inductor module 122 is connected to one end of the second linear inductor module 123, and the other end of the second linear inductor module 123 is connected to the ground terminal 130;

[0093] The Josephson junction 124 is connected in parallel across both ends of the second linear inductor module 123;

[0094] The qubit 110, the measurement input terminal 150, and the measurement output terminal 160 are respectively coupled to the corresponding coupling terminal 140;

[0095] Among them, the measurement input terminal 150 is used to input a microwave signal, the measurement output terminal 160 is used to output a voltage signal, and the voltage signal is used to indicate the state of the qubit 110; the measurement input terminal 150 can be connected to a device for generating microwaves, and the measurement output terminal 160 can be connected to a device for receiving the voltage signal.

[0096] Among them, the qubit 110 has the characteristics of superposition and entanglement, enabling the quantum computer to perform calculations faster than traditional computers on certain problems; the Josephson junction 124 (Josephson junction), also known as a superconducting tunnel junction, is usually a structure composed of two superconductors sandwiching a very thin barrier layer. The thickness of the barrier layer is less than the coherence length of Cooper electron pairs. The barrier layer includes, but is not limited to, an insulating layer or a semiconductor layer. In the Josephson junction 124, superconducting electrons can pass through the barrier layer from one superconductor to the other through the tunneling effect. Specifically, the Josephson junction 124 can be an S (superconductor)-I (semiconductor or insulator)-S (superconductor) structure, abbreviated as SIS. In addition to the structure of two superconductors sandwiching a very thin barrier layer, the Josephson junction 124 can also be formed by processing a part of the superconducting material into a thinner shape than other parts.

[0097] Based on this, the coupling end 140 refers to the port where multiple electrical components in a circuit are interconnected or interact with each other. The amplifying circuit 120 includes a capacitor module 121, a first linear inductor module 122, a second linear inductor module 123, and a Josephson junction 124. The Josephson junction 124 can be regarded as a kind of nonlinear inductor module. Since the Josephson junction 124 is in parallel with the second linear inductor module 123, and the coupling end 140, the first linear inductor module 122, the second linear inductor module 123, and the grounding end 130 are connected in series in sequence, and the coupling end 140, the capacitor module 121, and the grounding end 130 are connected in series in sequence. Under the action of the coupling end 140, the capacitor module 121, the second linear inductor module 123, and the Josephson junction 124 form a resonant circuit. The quantum circuit provided with the resonant circuit can amplify the signal of the qubit 110, thereby effectively measuring the state of the qubit 110.

[0098] Exemplarily, the measurement process of the state of the qubit 110 can be specifically as follows:

[0099] First, couple the qubit 110 to the amplifying circuit 120 through the coupling end 140. Among them, the qubit 110 is a two-level system. The low energy level can be regarded as the state |0>, and the high energy level can be regarded as the state |1>. When the state of the qubit 110 is superposed, the qubit 110 simultaneously has the states |0> and |1>. The qubit 110 can also collapse into one of the states, that is, the two ground states of the qubit 110 are the ground state |0> and the ground state |1> respectively;

[0100] Then, send a microwave signal with a specific signal frequency through the measurement input end 150, so that the amplifying circuit 120 can absorb photons when the qubit 110 is in the ground state |1>, but the amplifying circuit 120 will not absorb photons when the qubit 110 is in the ground state |0>. This is equivalent to mapping the ground state |0> and the ground state |1> of the qubit 110 to whether the amplifying circuit 120 absorbs photons;

[0101] Then, when the amplifying circuit 120 absorbs photons, it can transition to a high energy level and then jump to another frequency. Measure the output voltage signal through the measurement output end 160. Then, determine the frequency of the amplifying circuit 120 through the voltage signal, and then determine the state of the qubit 110 through the frequency of the amplifying circuit 120, so as to effectively measure the state of the qubit 110.

[0102] On this basis, the first linear inductor module 122 and the second linear inductor module 123 are connected in series, and the Josephson junction 124 is connected in parallel with the second linear inductor module 123, which is equivalent to the Josephson junction 124 also being connected in series with the first linear inductor module 122. The impedance of the first linear inductor module 122 is frequency-dependent. Within a certain frequency range, the impedance of the first linear inductor module 122 changes linearly. By reasonably selecting the parameters of the first linear inductor module 122, it can be ensured that the first linear inductor module 122 exhibits a linear impedance characteristic within a specific operating frequency range. Under the action of the first linear inductor module 122, the nonlinearity of the amplifier circuit 120 can be reduced. While meeting the amplification requirements, the coupling between the amplifier circuit 120 and the outside world can be reduced, thereby reducing the energy leakage of the qubit 110 and improving the accuracy of the measurement results. Moreover, the amplifier circuit 120 can be directly coupled to the qubit 110 without setting other intermediate devices, thereby reducing the circuit complexity of the qubit 110 measurement.

[0103] Specifically, referring to Figure 2 , Figure 2 is an optional potential energy schematic diagram of the amplifier circuit provided by the embodiment of the present application.

[0104] Among them, the potential energy schematic diagram of the amplifier circuit includes two potential wells. In the process of the left potential well in the figure, when the amplifier circuit absorbs photons, it jumps from the local minimum of the metastable state to a high energy level; then, in the process of the right potential well in the figure, it will jump to another frequency. By measuring the voltage signal of the amplifier circuit coupled to the measurement input terminal at the measurement input terminal, and then determining the frequency of the amplifier circuit through the voltage signal, the state of the qubit can be determined by the frequency of the amplifier circuit.

[0105] In a possible implementation manner, for a quantum circuit, the quantum circuit includes a qubit, an amplifier circuit, a coupling terminal, a measurement input terminal, and a measurement output terminal. Specifically, the amplifier circuit includes a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction. At this time, the qubit, the measurement input terminal, and the measurement output terminal are respectively coupled to the same coupling terminal.

[0106] Specifically, referring to Figure 3 , Figure 3 is the first optional circuit schematic diagram of the quantum circuit provided by the embodiment of the present application.

[0107] Among them, the qubit is formed by the parallel connection of a capacitor C1 and a Josephson junction J2. One end of the capacitor C1 is coupled to the coupling end 301 through a capacitor C2, and the other end of the capacitor C1 is connected to the ground end 302. The measurement input end a is coupled to the coupling end 301 through a capacitor C4, and the measurement output end b is coupled to the coupling end 301 through a capacitor C4. The capacitor module is the capacitor C3, the first linear inductor module is the inductor L1, and the second linear inductor module is the inductor L2. One end of the capacitor C3 is connected to the coupling end 301, and the other end of the capacitor C3 is connected to the ground end 302. One end of the inductor L1 is connected to the coupling end 301, the other end of the inductor L1 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to the ground end 302. The Josephson junction J1 is connected in parallel across both ends of the inductor L2.

[0108] Among them, the qubit can also be formed in other forms, which are not limited in the embodiments of the present application.

[0109] In a possible implementation manner, for the quantum circuit, the number of amplifier circuits and coupling ends is two. The two amplifier circuits share the same Josephson junction, and the capacitor modules and the first linear inductor modules of each amplifier circuit are respectively connected to their corresponding coupling ends.

[0110] Among them, the quantum circuit includes two amplifier circuits, specifically referring to that the quantum circuit includes amplifier circuits of two modes, that is, the quantum circuit has a two-mode structure. In the quantum circuit with a two-mode structure, the two-mode amplifier circuits share the same Josephson junction, and tunneling will occur simultaneously. Since the capacitor modules and the first linear inductor modules of each amplifier circuit are respectively connected to their corresponding coupling ends, that is, the quantum circuit includes two mutually isolated coupling ends, and the influence between the two coupling ends is less, or even there is no mutual influence, so that the signals between the two coupling ends will not interfere with each other. Under the isolation of the two coupling ends, the qubit is isolated from the external environment, and the qubit cannot directly leak energy to the external environment through the second-mode amplifier circuit, which can effectively protect the qubit. In addition, under the coupling action of one of the coupling ends, one capacitor module, one second linear inductor module, and the Josephson junction form a resonant circuit. Under the coupling action of the other coupling end, the other capacitor module, the other second linear inductor module, and the Josephson junction also form a resonant circuit. Therefore, the quantum circuit with a two-mode structure provided with a resonant circuit can amplify the signal of the qubit, and further realize the effective measurement of the qubit state.

[0111] Exemplarily, the measurement process of the qubit state can be specifically as follows:

[0112] First, couple the amplifier circuit of the first mode to the qubit through the corresponding coupling terminal, couple the amplifier circuit of the second mode to the measurement input terminal through the corresponding coupling terminal, and at the same time, couple the amplifier circuit of the second mode to the measurement output terminal through the corresponding coupling terminal. Here, the qubit is a two-level system, the low energy level can be regarded as the state |0>, and the high energy level can be regarded as the state |1>. When the state of the qubit is superposed, the qubit simultaneously has the states |0> and |1>, and the qubit can also collapse into one of the states, that is, the two ground states of the qubit are the ground state |0> and the ground state |1> respectively;

[0113] Then, input a microwave signal with a specific signal frequency through the measurement input terminal, so that the amplifier circuit can absorb photons when the qubit is in the ground state |1>, but the amplifier circuit will not absorb photons when the qubit is in the ground state |0>. This is equivalent to mapping the ground state |0> and the ground state |1> of the qubit to whether the amplifier circuit of the first mode directly coupled to the qubit can absorb photons;

[0114] Then, after the amplifier circuit of the first mode directly coupled to the qubit absorbs photons, it will cause the frequencies of the amplifier circuits of the two modes to jump simultaneously. Obtain the voltage signal of the amplifier circuit of the second mode coupled to the measurement input terminal through the measurement input terminal, and then determine the frequency of the amplifier circuit of the second mode, so as to realize the effective measurement of the qubit state.

[0115] In a possible implementation, for the quantum circuit, the two amplifier circuits include a first amplifier circuit and a second amplifier circuit, the two coupling terminals include a first coupling terminal and a second coupling terminal, and the two amplifier circuits also share the same second linear inductor module;

[0116] One end of the capacitor module in the first amplifier circuit is connected to the first coupling terminal, and the other end of the capacitor module in the first amplifier circuit is connected to the ground terminal;

[0117] One end of the capacitor module in the second amplifier circuit is connected to the second coupling terminal, and the other end of the capacitor module in the second amplifier circuit is connected to the ground terminal;

[0118] One end of the first linear inductor module in the first amplifier circuit is connected to the first coupling terminal, and one end of the first linear inductor module in the second amplifier circuit is connected to the second coupling terminal;

[0119] One end of the second linear inductor module is respectively connected to the other end of the first linear inductor module in the first amplifier circuit and the other end of the first linear inductor module in the second amplifier circuit, and the other end of the second linear inductor module is connected to the ground terminal.

[0120] Among them, in a quantum circuit with a dual-mode structure, in addition to sharing the same Josephson junction, the first amplification circuit and the second amplification circuit also share the same second linear inductor module. Specifically, the quantum circuit includes a first coupling end, a second coupling end, two capacitor modules, two first linear inductor modules, one second linear inductor module, and one Josephson junction. The two first linear inductor modules are connected to the same second linear inductor module, and the Josephson junction is connected in parallel with the second linear inductor module.

[0121] Based on this, since the first amplification circuit and the second amplification circuit share the same second linear inductor module, the circuit complexity of qubit measurement can be reduced. The first amplification circuit and the second amplification circuit share the same Josephson junction, and tunneling will occur simultaneously. Since the two capacitor modules are respectively connected to their corresponding coupling ends, and the two first linear inductor modules are also respectively connected to their corresponding coupling ends, the signals between the first coupling end and the second coupling end will not interfere with each other. Under the isolation of the two coupling ends and the two amplification circuits, the qubit is isolated from the external environment, and the qubit cannot directly leak energy to the external environment through the amplification circuit in the mode of the second amplification circuit, which can effectively protect the qubit. In addition, each of the two amplification circuits forms its own resonant circuit. Therefore, the quantum circuit with a dual-mode structure provided with a resonant circuit can amplify the signal of the qubit, and then effectively measure the state of the qubit without additional measurement conversion steps.

[0122] Specifically, referring to Figure 4 , Figure 4 is the second optional circuit schematic diagram of the quantum circuit provided by the embodiment of the present application.

[0123] Among them, the qubit is formed by the parallel connection of a capacitor C1 and a Josephson junction J2. One end of the capacitor C1 is coupled to the first coupling end 401 through a capacitor C2, and the other end of the capacitor C1 is connected to the ground end 403. The measurement input terminal a is coupled to the second coupling end 402 through a capacitor C4, and the measurement output terminal b is coupled to the second coupling end 402 through a capacitor C4. The capacitor module in the first amplifier circuit is the capacitor C3, the capacitor module in the second amplifier circuit is the capacitor C5, the first linear inductor module in the first amplifier circuit is the inductor L1, the first linear inductor module in the second amplifier circuit is the inductor L3, the second linear inductor module is the inductor L2. One end of the capacitor C3 is connected to the first coupling end 401, the other end of the capacitor C3 is connected to the ground end 403, one end of the capacitor C5 is connected to the second coupling end 402, the other end of the capacitor C5 is connected to the ground end 403, one end of the inductor L1 is connected to the first coupling end 401, one end of the inductor L3 is connected to the second coupling end 402, one end of the inductor L2 is respectively connected to the other end of the inductor L1 and the other end of the inductor L3, the other end of the inductor L2 is connected to the ground end 403, and the Josephson junction J1 is connected in parallel across both ends of the inductor L2.

[0124] In a possible implementation, for the quantum circuit, the two amplifier circuits include a first amplifier circuit and a second amplifier circuit, and the two coupling ends include a first coupling end and a second coupling end;

[0125] One end of the capacitor module in the first amplifier circuit is connected to the first coupling end, and the other end of the capacitor module in the first amplifier circuit is connected to the ground end;

[0126] One end of the capacitor module in the second amplifier circuit is connected to the second coupling end, and the other end of the capacitor module in the second amplifier circuit is connected to the ground end;

[0127] One end of the first linear inductor module in the first amplifier circuit is connected to the first coupling end, the other end of the first linear inductor module in the first amplifier circuit is connected to one end of the second linear inductor module in the first amplifier circuit, and the other end of the second linear inductor module in the first amplifier circuit is connected to the ground end;

[0128] One end of the first linear inductor module in the second amplifier circuit is connected to the second coupling end, the other end of the first linear inductor module in the second amplifier circuit is connected to one end of the second linear inductor module in the second amplifier circuit, and the other end of the second linear inductor module in the second amplifier circuit is connected to the ground end.

[0129] Among them, in a quantum circuit with a dual-mode structure, the first amplification circuit and the second amplification circuit share only the same Josephson junction. Specifically, the quantum circuit includes a first coupling end, a second coupling end, two capacitor modules, two first linear inductor modules, two second linear inductor modules, and a Josephson junction. The two first linear inductor modules are respectively connected to different second linear inductor modules, and the two second linear inductor modules are both connected in parallel with the Josephson junction.

[0130] Based on this, since the first amplification circuit and the second amplification circuit respectively include their own capacitor modules, first linear inductor modules, and second linear inductor modules, the two capacitor modules are respectively connected to their corresponding coupling ends, and the two first linear inductor modules are also respectively connected to their corresponding coupling ends. The signals between the two coupling ends will not interfere with each other. Under the isolation of the two coupling ends and the two amplification circuits, the qubit is isolated from the external environment, and the qubit cannot directly leak energy to the external environment through the amplification circuit of the second mode, which can effectively protect the qubit. In addition, the first amplification circuit and the second amplification circuit both form their own resonant circuits. Therefore, the quantum circuit with a dual-mode structure provided with a resonant circuit can amplify the signal of the qubit, and then effectively measure the state of the qubit without additional measurement conversion steps.

[0131] Specifically, referring to Figure 5 , Figure 5 is the third optional circuit schematic diagram of the quantum circuit provided by the embodiment of the present application.

[0132] Among them, the qubit is formed by the parallel connection of a capacitor C1 and a Josephson junction J2. One end of the capacitor C1 is coupled to the first coupling end 501 through a capacitor C2, and the other end of the capacitor C1 is connected to the ground end 503. The measurement input end a is coupled to the second coupling end 502 through a capacitor C4, and the measurement output end b is coupled to the second coupling end 502 through a capacitor C4. The capacitor module in the first amplifier circuit is the capacitor C3, the capacitor module in the second amplifier circuit is the capacitor C5, the first linear inductor module in the first amplifier circuit is the inductor L1, the first linear inductor module in the second amplifier circuit is the inductor L3, the second linear inductor module in the first amplifier circuit is the inductor L2, and the second linear inductor module in the second amplifier circuit is the inductor L4. One end of the capacitor C3 is connected to the first coupling end 501, and the other end of the capacitor C3 is connected to the ground end 503. One end of the capacitor C5 is connected to the second coupling end 502, and the other end of the capacitor C5 is connected to the ground end 503. One end of the inductor L1 is connected to the first coupling end 501, the other end of the inductor L1 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to the ground end 503. One end of the inductor L3 is connected to the second coupling end 502, the other end of the inductor L3 is connected to one end of the inductor L4, and the other end of the inductor L4 is connected to the ground end 503. The Josephson junction J1 is connected in parallel across both ends of the inductor L2, and the Josephson junction J1 is also connected in parallel across both ends of the inductor L4.

[0133] In a possible implementation, for the quantum circuit, the quantum circuit further includes a third linear inductor module and a current input end for inputting current to the third linear inductor module. The third linear inductor module is magnetically coupled to the second linear inductor module, and the third linear inductor module is connected to the current input end.

[0134] Among them, the impedance of the third linear inductor module is related to the frequency. Within a certain frequency range, the impedance of the third linear inductor module changes linearly. By reasonably selecting the parameters of the third linear inductor module, it can be ensured that the third linear inductor module exhibits a linear impedance characteristic within a specific operating frequency range. Since the second linear inductor module and the Josephson junction are in a parallel state in the resonant circuit, and the third linear inductor module is magnetically coupled to the second linear inductor module, therefore, the current state of the third linear inductor module can be adjusted through the current input end, and then the electromagnetic coupling effect between the second linear inductor module and the third linear inductor module can be adjusted to adjust the resonant frequency of the resonant circuit. It is equivalent that the third linear inductor module and the current input end form a magnetic flux bias line, and the magnetic flux bias line can bias the resonant circuit. When the resonant circuit is appropriately biased, the amplifier circuit can absorb photons when the qubit is in the second state, and the amplifier circuit does not absorb photons when the qubit is in the first state.

[0135] Specifically, when the quantum circuit includes an amplifying circuit and a coupling terminal, that is, the quantum circuit may include a coupling terminal, a capacitance module, a first linear inductor module, a second linear inductor module, and a Josephson junction. Under the action of the coupling terminal, the capacitance module, the second linear inductor module, and the Josephson junction form a resonant circuit. At this time, the quantum circuit further includes a third linear inductor module and a current input terminal. The third linear inductor module is mutually inductively connected to the second linear inductor module. The current state of the third linear inductor module can be adjusted through the current input terminal, and then the electromagnetic coupling effect between the second linear inductor module and the third linear inductor module can be adjusted, effectively adjusting the resonant frequency of the resonant circuit, which is equivalent to effectively biasing the resonant circuit.

[0136] When the quantum circuit includes two amplifying circuits and two coupling terminals, that is, the quantum circuit may include a first coupling terminal, a second coupling terminal, two capacitance modules, two first linear inductor modules, a second linear inductor module, and a Josephson junction. The quantum circuit has a two-mode structure. Under the coupling action of the first coupling terminal, the capacitance module in the first amplifying circuit, the second linear inductor module in the first amplifying circuit, and the Josephson junction form a resonant circuit. Under the coupling action of the second coupling terminal, the capacitance module in the second amplifying circuit, the second linear inductor module in the second amplifying circuit, and the Josephson junction also form a resonant circuit. At this time, the quantum circuit further includes two third linear inductor modules and two current input terminals. One current input terminal is used to input current to one of the third linear inductor modules, and the other current input terminal is used to input current to the other third linear inductor module. One current input terminal is mutually inductively connected to the second linear inductor module in the first amplifying circuit, and the other current input terminal is mutually inductively connected to the second linear inductor module in the second amplifying circuit. The current state of the corresponding third linear inductor module can be adjusted through the current input terminal, and then the electromagnetic coupling effect between the corresponding second linear inductor module and the corresponding third linear inductor module can be adjusted, effectively adjusting the resonant frequency of the corresponding resonant circuit, which is equivalent to effectively biasing the resonant circuit.

[0137] In a possible implementation manner, for the quantum circuit, the capacitance module includes a distributed capacitance, and the amplifying circuit is fabricated by a planar process.

[0138] Among them, the amplification circuit is prepared by planar technology. Planar technology can be divided into two categories: physical preparation methods and chemical preparation methods. Among them, the physical preparation method specifically refers to physical processes such as thermal evaporation or sputtering of surface atoms of a substance when bombarded by particles to achieve the transfer of substance atoms from the source substance to the surface of the substrate material. For example, physical vapor deposition (PVD), spin coating, electroplating, etc.; the chemical preparation method refers to introducing the vapor of gaseous reactants or liquid reactants containing the elements constituting the thin film into the process chamber with a reasonable gas flow rate, and chemical reactions occur on the surface of the substrate and thin films are deposited on the surface of the substrate. For example, chemical vapor deposition (CVD) and epitaxy, etc.; in the process of preparing the amplification device, the physical preparation method and the chemical preparation method need to complement each other. The physical preparation method can be used to deposit metal wires and metal compound thin films, etc., and the physical preparation method can deposit insulating materials through the reaction between different gases.

[0139] Based on this, a distributed capacitor refers to a capacitor that is dispersed or distributed over a large area or volume and has the capacitance property distributed between circuit elements. In the amplification device prepared by planar technology, using a distributed capacitor can optimize the circuit performance, and can also make more effective use of space and reduce the physical size of the amplification device.

[0140] Specifically, in a possible implementation manner, for a quantum circuit, the capacitance module, the first linear inductor module, the second linear inductor module, and the Josephson junctions in the amplification circuit are integrated into the same device; in another possible implementation manner, the capacitance module, the second linear inductor module, and the Josephson junctions in the amplification circuit are integrated into the same device, and the first linear inductor module in the amplification circuit belongs to another device.

[0141] Referring to Figure 6 , Figure 6 FIG.

[0142] shows an optional structural schematic diagram of the amplification device provided by the embodiment of the present application. The amplification device includes an amplification circuit 610, a ground terminal 620, and a coupling terminal 630. The amplification circuit 610 includes a capacitance module 611, a first linear inductor module 612, a second linear inductor module 613, and a Josephson junction 614;

[0143] One end of the capacitance module 611 is connected to the coupling terminal 630, and the other end of the capacitance module 611 is connected to the ground terminal 620;

[0144] The Josephson junction 614 is connected in parallel across both ends of the second linear inductor module 613.

[0145] Based on this, the coupling end 630 refers to the port where multiple electrical components in a circuit are interconnected or interact with each other. The amplifier circuit 610 includes a capacitor module 611, a first linear inductor module 612, a second linear inductor module 613, and a Josephson junction 614. The Josephson junction 614 can be regarded as a kind of nonlinear inductor module. Since the Josephson junction 614 and the second linear inductor module 613 are connected in parallel, and the coupling end 630, the first linear inductor module 612, the second linear inductor module 613, and the ground end 620 are connected in series in sequence, and the coupling end 630, the capacitor module 611, and the ground end 620 are connected in series in sequence. Under the action of the coupling end 630, the capacitor module 611, the second linear inductor module 613, and the Josephson junction 614 form a resonant circuit. The amplifier device provided with the resonant circuit can amplify the signal of the qubit, thereby realizing an effective measurement of the state of the qubit.

[0146] First, couple the qubit to the amplifier circuit 610 through the coupling end 630. Among them, the qubit is a two-level system. The low energy level can be regarded as the state |0>, and the high energy level can be regarded as the state |1>. When the state of the qubit is superposed, the qubit has both the state |0> and the state |1> at the same time. The qubit can also collapse into one of the states, that is, the two ground states of the qubit are the ground state |0> and the ground state |1> respectively;

[0147] Then, send a microwave signal with a specific signal frequency to the amplifier circuit 610, so that the amplifier circuit 610 can absorb photons when the qubit is in the ground state |1>, but the amplifier circuit 610 will not absorb photons when the qubit is in the ground state |0>, which is equivalent to mapping the ground state |0> and the ground state |1> of the qubit to whether the amplifier circuit 610 absorbs photons;

[0148] Then, when the amplifier circuit 610 absorbs photons, it can transition to a high energy level and then jump to another frequency. By measuring the frequency of the amplifier circuit 610, the state of the qubit can be determined, and an effective measurement of the state of the qubit can be realized.

[0149] On this basis, the first linear inductor module 612 and the second linear inductor module 613 are connected in series, and the Josephson junction 614 is connected in parallel with the second linear inductor module 613, which is equivalent to the Josephson junction 614 being also connected in series with the first linear inductor module 612. The impedance of the first linear inductor module 612 is frequency-dependent. Within a certain frequency range, the impedance of the first linear inductor module 612 changes linearly. By reasonably selecting the parameters of the first linear inductor module 612, it can be ensured that the first linear inductor module 612 exhibits a linear impedance characteristic within a specific operating frequency range. Under the action of the first linear inductor module 612, the nonlinearity of the amplifier circuit 610 can be reduced. While meeting the amplification requirements, the coupling between the amplifier circuit 610 and the outside can be reduced, thereby reducing the energy leakage of the qubit and improving the accuracy of the measurement result. Moreover, the amplifier circuit 610 can be directly coupled to the qubit without setting other intermediate devices, thereby reducing the circuit complexity of qubit measurement.

[0150] In a possible implementation manner, for the amplification device, the amplification device includes an amplifier circuit, a coupling end, and a grounding end. Specifically, the amplifier circuit includes a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction.

[0151] Specifically, referring to Figure 7 , Figure 7 is the first optional circuit schematic diagram of the amplification device provided by the embodiment of the present application.

[0152] Among them, the capacitor module is capacitor C3, the first linear inductor module is inductor L1, the second linear inductor module is inductor L2. One end of capacitor C3 is connected to the coupling end 701, the other end of capacitor C3 is connected to the grounding end 702. One end of inductor L1 is connected to the coupling end 701, the other end of inductor L1 is connected to one end of inductor L2. The other end of inductor L2 is connected to the grounding end 702. The Josephson junction J1 is connected in parallel across the two ends of inductor L2.

[0153] Among them, the qubit can also be formed in other forms, which is not limited in the embodiment of the present application.

[0154] In a possible implementation manner, for the amplification device, the number of both the amplifier circuit and the coupling end is two. The two amplifier circuits share the same Josephson junction, and the capacitor module and the first linear inductor module of each amplifier circuit are respectively connected to their corresponding coupling ends.

[0155] Among them, the amplifying device includes two amplifying circuits, specifically referring to that the amplifying device includes two modes of amplifying circuits, that is, the amplifying device has a dual-mode structure. In the amplifying device with a dual-mode structure, the two modes of amplifying circuits share the same Josephson junction and tunneling occurs simultaneously. Since the capacitance modules and the first linear inductance modules of each amplifying circuit are respectively connected to their corresponding coupling ends, that is, the amplifying device includes two mutually isolated coupling ends, and the influence between the two coupling ends is less, or even there is no mutual influence, so that the signals between the two coupling ends will not interfere with each other. Under the isolation of the two coupling ends, the qubit is isolated from the external environment, and the qubit cannot directly leak energy to the external environment through the amplifying circuit of the second mode, which can effectively protect the qubit. In addition, under the coupling action of one of the coupling ends, one capacitance module, one second linear inductance module and the Josephson junction form a resonant circuit. Under the coupling action of the other coupling end, the other capacitance module, the other second linear inductance module and the Josephson junction also form a resonant circuit. Therefore, the amplifying device with a dual-mode structure provided with a resonant circuit can amplify the signal of the qubit, and then effectively measure the state of the qubit.

[0156] Exemplarily, the measurement process of the qubit state can be specifically as follows:

[0157] First, couple the amplifying circuit of the first mode to the qubit through the corresponding coupling end, and couple the amplifying circuit of the second mode to the measurement input end through the corresponding coupling end. At the same time, also couple the amplifying circuit of the second mode to the measurement output end through the corresponding coupling end. Among them, the qubit is a two-level system, and the low energy level can be regarded as the state |0>, and the high energy level can be regarded as the state |1>. When the state of the qubit is superposed, the qubit has both the state |0> and the state |1> at the same time, and the qubit can also collapse into one of the states, that is, the two ground states of the qubit are the ground state |0> and the ground state |1> respectively;

[0158] Then, input a microwave signal with a specific signal frequency through the measurement input end, so that the amplifying circuit can absorb photons when the qubit is in the ground state |1>, but the amplifying circuit will not absorb photons when the qubit is in the ground state |0>. This is equivalent to mapping the ground state |0> and the ground state |1> of the qubit to whether the amplifying circuit of the first mode directly coupled to the qubit can absorb photons;

[0159] Then, after the amplifying circuit of the first mode directly coupled to the qubit absorbs photons, it will cause the frequencies of the two modes of amplifying circuits to jump simultaneously. By obtaining the voltage signal of the amplifying circuit of the second mode coupled to the measurement input end through the measurement input end, and then determining the frequency of the amplifying circuit of the second mode, the effective measurement of the qubit state can be realized.

[0160] In a possible implementation, for the amplifying device, the two amplifying circuits include a first amplifying circuit and a second amplifying circuit, the two coupling ends include a first coupling end and a second coupling end, and the two amplifying circuits also share the same second linear inductor module;

[0161] One end of the capacitor module in the first amplifying circuit is connected to the first coupling end, and the other end of the capacitor module in the first amplifying circuit is connected to the ground end;

[0162] One end of the capacitor module in the second amplifying circuit is connected to the second coupling end, and the other end of the capacitor module in the second amplifying circuit is connected to the ground end;

[0163] One end of the first linear inductor module in the first amplifying circuit is connected to the first coupling end, and the other end of the first linear inductor module in the first amplifying circuit is respectively connected to one end of the second linear inductor module and one end of the Josephson junction. The other end of the second linear inductor module and the other end of the Josephson junction are respectively connected to the ground end;

[0164] One end of the first linear inductor module in the second amplifying circuit is connected to the second coupling end, and the other end of the first linear inductor module in the second amplifying circuit is respectively connected to one end of the second linear inductor module and one end of the Josephson junction.

[0165] Among them, in the amplifying device with a dual-mode structure, the first amplifying circuit and the second amplifying circuit not only share the same Josephson junction, but also share the same second linear inductor module. Specifically, the amplifying device includes a first coupling end, a second coupling end, two capacitor modules, two first linear inductor modules, one second linear inductor module and one Josephson junction. The two first linear inductor modules are connected to the same second linear inductor module, and the Josephson junction is connected in parallel with the second linear inductor module.

[0166] Based on this, since the first amplifying circuit and the second amplifying circuit share the same second linear inductor module, the circuit complexity of qubit measurement can be reduced. The first amplifying circuit and the second amplifying circuit share the same Josephson junction, and tunneling will occur simultaneously. Since the two capacitor modules are respectively connected to their corresponding coupling ends, and the two first linear inductor modules are also respectively connected to their corresponding coupling ends, the signals between the first coupling end and the second coupling end will not interfere with each other. Under the isolation of the two coupling ends and the two amplifying circuits, the qubit is isolated from the external environment, and the qubit cannot directly leak energy to the external environment through the amplifying circuit of the mode in the second amplifying circuit, which can effectively protect the qubit. In addition, the two amplifying circuits both form their own resonant circuits. Therefore, the amplifying device with a dual-mode structure provided with a resonant circuit can amplify the signal of the qubit, and then effectively measure the state of the qubit without additional measurement conversion steps.

[0167] Specifically, referring to Figure 8 , Figure 8 which is the second alternative circuit schematic diagram of the amplification device provided by the embodiment of the present application.

[0168] Among them, the capacitor module in the first amplification circuit is capacitor C3, the capacitor module in the second amplification circuit is capacitor C5, the first linear inductor module in the first amplification circuit is inductor L1, the first linear inductor module in the second amplification circuit is inductor L3, the second linear inductor module is inductor L2. One end of capacitor C3 is connected to the first coupling end 801, the other end of capacitor C3 is connected to the ground end 803, one end of capacitor C5 is connected to the second coupling end 802, the other end of capacitor C5 is connected to the ground end 803, one end of inductor L1 is connected to the first coupling end 801, one end of inductor L3 is connected to the second coupling end 802, one end of inductor L2 is respectively connected to the other end of inductor L1 and the other end of inductor L3, the other end of inductor L2 is connected to the ground end 803, and the Josephson junction J1 is connected in parallel across the two ends of inductor L2.

[0169] In a possible implementation manner, for the amplification device, the two amplification circuits include a first amplification circuit and a second amplification circuit, and the two coupling ends include a first coupling end and a second coupling end;

[0170] One end of the capacitor module in the first amplification circuit is connected to the first coupling end, and the other end of the capacitor module in the first amplification circuit is connected to the ground end;

[0171] One end of the capacitor module in the second amplification circuit is connected to the second coupling end, and the other end of the capacitor module in the second amplification circuit is connected to the ground end;

[0172] One end of the first linear inductor module in the first amplification circuit is connected to the first coupling end, the other end of the first linear inductor module in the first amplification circuit is connected to one end of the second linear inductor module in the first amplification circuit, and the other end of the second linear inductor module in the first amplification circuit is connected to the ground end;

[0173] One end of the first linear inductor module in the second amplification circuit is connected to the second coupling end, the other end of the first linear inductor module in the second amplification circuit is connected to one end of the second linear inductor module in the second amplification circuit, and the other end of the second linear inductor module in the second amplification circuit is connected to the ground end.

[0174] Among them, in an amplification device with a dual-mode structure, the first amplification circuit and the second amplification circuit only share the same Josephson junction. Specifically, the amplification device includes a first coupling end, a second coupling end, two capacitor modules, two first linear inductor modules, two second linear inductor modules, and a Josephson junction. The two first linear inductor modules are respectively connected to different second linear inductor modules, and the two second linear inductor modules are both connected in parallel with the Josephson junction.

[0175] Based on this, since the first amplification circuit and the second amplification circuit respectively include their own capacitor modules, first linear inductor modules, and second linear inductor modules, the two capacitor modules are respectively connected to their corresponding coupling ends, and the two first linear inductor modules are also respectively connected to their corresponding coupling ends. The signals between the two coupling ends will not interfere with each other. Under the isolation of the two coupling ends and the two amplification circuits, the qubit is isolated from the external environment, and the qubit cannot directly leak energy to the external environment through the amplification circuit of the second mode, which can effectively protect the qubit. In addition, the first amplification circuit and the second amplification circuit both form their own resonant circuits. Therefore, the amplification device with a dual-mode structure provided with a resonant circuit can amplify the signal of the qubit, and further realize the effective measurement of the qubit state without additional measurement conversion steps.

[0176] Specifically, referring to Figure 9 , Figure 9 is the third optional circuit schematic diagram of the amplification device provided by the embodiment of the present application.

[0177] Among them, the capacitor module in the first amplification circuit is capacitor C3, the capacitor module in the second amplification circuit is capacitor C5, the first linear inductor module in the first amplification circuit is inductor L1, the first linear inductor module in the second amplification circuit is inductor L3, the second linear inductor module in the first amplification circuit is inductor L2, the second linear inductor module in the second amplification circuit is inductor L4. One end of capacitor C3 is connected to the first coupling end 901, and the other end of capacitor C3 is connected to the ground end 903; one end of capacitor C5 is connected to the second coupling end 902, and the other end of capacitor C5 is connected to the ground end 903; one end of inductor L1 is connected to the first coupling end 901, the other end of inductor L1 is connected to one end of inductor L2, and the other end of inductor L2 is connected to the ground end 903; one end of inductor L3 is connected to the second coupling end 902, the other end of inductor L3 is connected to one end of inductor L4, and the other end of inductor L4 is connected to the ground end 903. The Josephson junction J1 is connected in parallel at both ends of inductor L2, and the Josephson junction J1 is also connected in parallel at both ends of inductor L4.

[0178] In a possible implementation, for the amplification device, the amplification device further includes a third linear inductor module and a current input terminal for inputting current to the third linear inductor module. The third linear inductor module is mutually inductively connected to the second linear inductor module, and the third linear inductor module is connected to the current input terminal.

[0179] Among them, the impedance of the third linear inductor module is frequency-dependent. Within a certain frequency range, the impedance of the third linear inductor module changes linearly. By reasonably selecting the parameters of the third linear inductor module, it can be ensured that the third linear inductor module exhibits a linear impedance characteristic within a specific operating frequency range. Since the second linear inductor module and the Josephson junction are in parallel in the resonant circuit, and the third linear inductor module is mutually inductively connected to the second linear inductor module, therefore, the current state of the third linear inductor module can be adjusted through the current input terminal, and then the electromagnetic coupling effect between the second linear inductor module and the third linear inductor module can be adjusted to adjust the resonant frequency of the resonant circuit. It is equivalent that the third linear inductor module and the current input terminal form a magnetic flux bias line, and the magnetic flux bias line can bias the resonant circuit. When the resonant circuit is appropriately biased, the amplification circuit can absorb photons when the qubit is in the second state, and the amplification circuit does not absorb photons when the qubit is in the first state.

[0180] Specifically, when the amplification device includes an amplification circuit and a coupling terminal, that is, the amplification device can include a coupling terminal, a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction. Under the action of the coupling terminal, the capacitor module, the second linear inductor module, and the Josephson junction form a resonant circuit. At this time, the amplification device further includes a third linear inductor module and a current input terminal. The third linear inductor module is mutually inductively connected to the second linear inductor module. The current state of the third linear inductor module can be adjusted through the current input terminal, and then the electromagnetic coupling effect between the second linear inductor module and the third linear inductor module can be adjusted, which can effectively adjust the resonant frequency of the resonant circuit, equivalent to effectively biasing the resonant circuit.

[0181] When the amplification device includes two amplification circuits and two coupling ends, that is, the amplification device may include a first coupling end, a second coupling end, two capacitor modules, two first linear inductor modules, a second linear inductor module, and a Josephson junction, the amplification device has a dual-mode structure. Under the coupling action of the first coupling end, the capacitor module in the first amplification circuit, the second linear inductor module in the first amplification circuit, and the Josephson junction form a resonant circuit. Under the coupling action of the second coupling end, the capacitor module in the second amplification circuit, the second linear inductor module in the second amplification circuit, and the Josephson junction also form a resonant circuit. At this time, the amplification device further includes two third linear inductor modules and two current input ends. One current input end is used to input current to one of the third linear inductor modules, and the other current input end is used to input current to the other third linear inductor module. One current input end is mutually inductively connected to the second linear inductor module in the first amplification circuit, and the other current input end is mutually inductively connected to the second linear inductor module in the second amplification circuit. The current state of the corresponding third linear inductor module can be adjusted through the current input end, and then the electromagnetic coupling effect between the corresponding second linear inductor module and the corresponding third linear inductor module can be adjusted, which can effectively adjust the resonant frequency of the corresponding resonant circuit, equivalent to effectively biasing the resonant circuit.

[0182] In a possible implementation manner, for the amplification device, the capacitor module includes a distributed capacitor, and the amplification circuit is fabricated by a planar process.

[0183] Among them, the amplification circuit is fabricated by a planar process. The planar process can be divided into two categories: physical fabrication methods and chemical fabrication methods. Among them, the physical fabrication method specifically refers to using physical processes such as thermal evaporation or sputtering of surface atoms of a substance when bombarded by particles to achieve the transfer of substance atoms from the source substance to the surface of the substrate material. For example, physical vapor deposition (Physical Vapor Deposition, PVD), spin coating, electroplating, etc.; the chemical fabrication method refers to introducing the vapor of a gaseous reactant or a liquid reactant containing the elements constituting the thin film into the process chamber with a reasonable gas flow rate, and a chemical reaction occurs on the surface of the substrate and a thin film is deposited on the surface of the substrate. For example, chemical vapor deposition (Chemical Vapor Deposition, CVD) and epitaxy, etc.; during the process of fabricating the amplification device, the physical fabrication method and the chemical fabrication method need to complement each other. The physical fabrication method can be used to deposit metal wires and metal compound thin films, etc. The physical fabrication method can deposit insulating materials through the reaction between different gases.

[0184] Based on this, a distributed capacitor refers to a capacitor that is dispersed or distributed over a large area or volume, having capacitance properties distributed among circuit elements. In an amplification device fabricated using planar technology, the use of a distributed capacitor can optimize circuit performance, more effectively utilize space, and reduce the physical size of the amplification device.

[0185] Specifically, in one possible implementation, for an amplification device, the capacitance module, the first linear inductor module, the second linear inductor module, and the Josephson junctions in the amplification circuit are integrated into the same device; in another possible implementation, the capacitance module, the second linear inductor module, and the Josephson junctions in the amplification circuit are integrated into the same device, and the first linear inductor module in the amplification circuit belongs to another device.

[0186] In addition, another embodiment of the present application provides a chip structure, which includes the above-mentioned quantum circuit or includes the above-mentioned amplification device;

[0187] Based on this, the chip structure and the above-mentioned quantum circuit or the above-mentioned amplification device are based on the same inventive concept. By setting up a capacitance module, a second linear inductor module, and Josephson junctions to form a resonant circuit, the amplification effect of the quantum bit signal is achieved, and further, the effective measurement of the quantum bit state is realized. On this basis, the first linear inductor module is further set up to reduce the non-linearity of the amplification circuit. While meeting the amplification requirements, the coupling between the amplification circuit and the outside is reduced, thereby reducing the energy leakage of the quantum bit and improving the accuracy of the measurement result. Moreover, the amplification circuit can be directly coupled to the quantum bit without setting other intermediate devices, thereby reducing the circuit complexity of the quantum bit measurement.

[0188] Specifically, a quantum computer can be provided with this chip structure. Quantum bits have the characteristics of superposition and entanglement, enabling the quantum computer to perform calculations faster than traditional computers on certain problems.

[0189] The method provided by the embodiments of the present application can be applied to various scenarios, including but not limited to scenarios such as cloud technology, quantum computing, and intelligent transportation.

[0190] Refer to Figure 10 , Figure 10 which is an optional flowchart of the method for measuring the state of a quantum bit provided by the embodiments of the present application. This method for measuring the state of a quantum bit can be executed by a processor. The processor is connected to the measurement output terminal in the quantum circuit. This method for measuring the state of a quantum bit includes but is not limited to the following steps 1001 to step 1004.

[0191] Step 1001: When a microwave signal is input to the measurement input terminal, obtain the target voltage signal output from the measurement output terminal;

[0192] Among them, the above quantum circuit includes qubits, an amplification circuit, a ground terminal, a coupling terminal, a measurement input terminal, and a measurement output terminal. The amplification circuit includes a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction.

[0193] Among them, for the quantum circuit, the measurement input terminal and the measurement output terminal are respectively coupled to the corresponding coupling terminals. Specifically, the measurement input terminal and the measurement output terminal are respectively coupled to the same coupling terminal. From the description of the qubits of the above two-level system, it can be seen that by inputting a microwave signal through the measurement input terminal, when the qubit in the quantum circuit is in the second state, the amplification circuit can absorb photons, and when the qubit is in the first state, the amplification circuit does not absorb photons, which is equivalent to mapping the first state and the second state of the qubit to whether the amplification circuit absorbs photons. The amplification circuit in the quantum circuit can jump to a high energy level after absorbing photons and then jump to another frequency. The target voltage signal measured through the measurement output terminal can determine the frequency of the amplification circuit, and by measuring the frequency of the amplification circuit to determine the state of the qubit, an effective measurement of the qubit state can be achieved.

[0194] Step 1002: Determine a target phase and a target amplitude according to the target voltage signal, and determine a target measurement point in the corresponding first coordinate space according to the target phase and the target amplitude;

[0195] Among them, by performing signal processing on the target voltage signal, the corresponding target phase and target amplitude can be determined. Then, a coordinate space of a polar coordinate system is used as the first coordinate space, and then according to the target phase and the target amplitude, the corresponding target measurement point is determined in the first coordinate space;

[0196] For example, assuming that the position of the polar coordinate system is O and the position of the target measurement point is P, the length of the line segment OP is the target amplitude, and the angle between the line segment OP and the polar axis is the target phase. The polar coordinate system can also be converted into a rectangular coordinate system, where the abscissa of the rectangular coordinate system is used to represent the I value (in-phase), and the ordinate of the rectangular coordinate system is used to represent the Q value (quadrature).

[0197] Based on this, since the target voltage signal changes with the change of the frequency of the amplification circuit, by determining the target phase and the target amplitude through the target voltage signal, and then determining the target measurement point through the target phase and the target amplitude, the frequency of the amplification circuit can be determined by the position of the target measurement point in the first coordinate space, which is equivalent to determining the state of the qubit through the target measurement point.

[0198] Step 1003: Obtain a preset first sample point region and a second sample point region in the first coordinate space, where the first sample point region and the second sample point region are respectively used to indicate two different states of the qubit;

[0199] In the qubits of a two-level system, through the method of pre-measurement, the qubits in the first state can be measured multiple times in advance, and the first sample point region can be determined according to the region where the measurement points obtained from the measurements are located. Therefore, the first sample point region can indicate that the qubit is in the first state, and the qubits in the second state can be measured multiple times in advance, and the second sample point region can be determined according to the region where the measurement points obtained from the measurements are located. Therefore, the second sample point region can indicate that the qubit is in the second state.

[0200] Step 1004: Determine the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region.

[0201] Among them, the attribution relationship between the target measurement point and the first sample point region or the second sample point region can be determined by the following methods:

[0202] (1) Method 1: Determine whether the target measurement point is within the first sample point region or the second sample point region. When the target measurement point is within the first sample point region, it is determined that the target measurement point belongs to the first sample point region; when the target measurement point is within the second sample point region, it is determined that the target measurement point belongs to the second sample point region; when the target measurement point is outside the first sample point region and outside the second sample point region, it is determined that the target measurement point belongs to neither the first sample point region nor the second sample point region, and a new target measurement point can be selected for re-measurement.

[0203] (2) Method 2: Determine the first distance between the target measurement point and the first sample point region, and determine the second distance between the target measurement point and the second sample point region. When the first distance is less than the second distance, it is determined that the target measurement point belongs to the first sample point region; when the first distance is greater than the second distance, it is determined that the target measurement point belongs to the second sample point region; when the first distance is equal to the second distance, it is determined that the target measurement point belongs to neither the first sample point region nor the second sample point region, and a new target measurement point can be selected for re-measurement. Specifically, the first distance can refer to the distance between the target measurement point and the center of the first sample point region, or the first distance can also refer to the shortest distance between the target measurement point and the edge of the first sample point region. The second distance can refer to the distance between the target measurement point and the center of the second sample point region, or the second distance can also refer to the shortest distance between the target measurement point and the edge of the second sample point region.

[0204] In addition, the attribution relationship between the target measurement point and the first sample point region or the second sample point region can also be determined by other methods, which are not limited in this embodiment of the present application.

[0205] Based on this, when measuring the state of a qubit, by determining the target phase and target amplitude according to the target voltage signal, determining the target measurement point in the corresponding first coordinate space according to the target phase and target amplitude, obtaining a preset first sample point region and a second sample point region in the first coordinate space, and determining the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region, it is possible to quickly determine the state of the qubit in a coordinate matching manner based on the first sample point region and the second sample point region, thereby effectively improving the measurement efficiency of the qubit state.

[0206] In a possible implementation, the first sample point region and the second sample point region can be determined through the following steps: determining the signal frequency of the microwave signal; setting the state of the qubit to the first state, and whenever a microwave signal with the signal frequency is input to the measurement input terminal, obtaining the first sample voltage signal output by the measurement output terminal each time, determining the first sample measurement point corresponding to the first sample voltage signal in the first coordinate space, and obtaining the first sample point region according to multiple first sample measurement points; setting the state of the qubit to the second state, and whenever a microwave signal with the signal frequency is input to the measurement input terminal, obtaining the second sample voltage signal output by the measurement output terminal each time, determining the second sample measurement point corresponding to the second sample voltage signal in the first coordinate space, and obtaining the second sample point region according to multiple second sample measurement points.

[0207] In a qubit of a two-level system, the low energy level can be taken as the state |0>, and the high energy level can be taken as the state |1>. When the state of the qubit is superimposed, the qubit simultaneously has the states |0> and |1>, and the qubit can also collapse to one of the states, that is, the two ground states of the qubit are the ground state |0> and the ground state |1>. Assuming that setting the qubit to the first state means setting the state of the qubit to the ground state |0>, then setting the qubit to the second state means setting the state of the qubit to the ground state |1>;

[0208] Then, when sending a microwave signal with a specific signal frequency to the amplifier circuit, when the qubit is in the first state, the amplifier circuit does not absorb photons, and when the qubit is in the second state, the amplifier circuit can absorb photons, which is equivalent to mapping the first state and the second state of the qubit to whether the amplifier circuit absorbs photons, and directly encoding the number of photons absorbed by the amplifier circuit through the qubit.

[0209] Among them, when the amplifier circuit absorbs photons, it can transition to a high energy level and then jump to another frequency. The frequency of the amplifier circuit can be determined through the target voltage signal measured by the measurement output terminal, and the state of the qubit can be determined by measuring the frequency of the amplifier circuit, which can effectively measure the state of the qubit.

[0210] Based on this, in the first coordinate space, the first sample measurement point determined by the first sample voltage signal and the second sample measurement point determined by the second sample voltage signal can be determined. The positions of the first sample measurement point and the second sample measurement point in the first coordinate space are different. Therefore, before obtaining the target voltage signal output by the measurement output end, the first sample point region where the first sample measurement point is located and the second sample point region where the second sample measurement point is located can be distinguished in the first coordinate space. Subsequently, based on the first sample point region and the second sample point region, it can be determined which region the target measurement point corresponding to the currently measured target voltage signal belongs to, and then the state of the qubit can be determined.

[0211] The specific process of determining the first sample point region will be described in detail below.

[0212] First, set the state of the qubit to the first state;

[0213] Then, input a microwave signal with a specific signal frequency through the measurement input end. When the qubit is in the first state, the amplifier circuit will not absorb photons;

[0214] Then, obtain the corresponding first sample voltage signal through the measurement output end. The first sample voltage signal is used to indicate that the amplifier circuit will not absorb photons when the qubit is in the first state;

[0215] Then, perform corresponding signal processing on the first sample voltage signal to obtain the corresponding first phase and first amplitude. The first sample voltage signal can be demodulated, sampled, and restored. The phase of the restored result is used as the first phase, and the amplitude of the restored result is used as the first amplitude;

[0216] For example, based on the Fourier transform, the first sample voltage signal in the time domain is converted to the frequency domain, and the phase and amplitude of each frequency component can be determined in the frequency domain;

[0217] Then, take a coordinate space of a polar coordinate system as the first coordinate space, and then determine the corresponding first sample measurement point in the first coordinate space according to the first phase and the first amplitude. Therefore, the first sample measurement point is used to indicate that the amplifier circuit will not absorb photons when the qubit is in the first state;

[0218] For example, assume that the position of the polar coordinate system is O and the position of the first sample measurement point is A. Then the length of the line segment OA is the first amplitude, and the angle between the line segment OA and the polar axis is the first phase. The polar coordinate system can also be converted into a rectangular coordinate system. The abscissa of this rectangular coordinate system is used to represent the I value (in-phase), and the ordinate of this rectangular coordinate system is used to represent the Q value (quadrature);

[0219] Then, after multiple measurements, a plurality of first sample measurement points are determined in the first coordinate space;

[0220] Then, according to the region where the plurality of first sample measurement points are located in the first coordinate space, a first sample point region is determined;

[0221] For example, a first target bounding box containing all the first sample measurement points is determined in the first coordinate space, and the region within the first target bounding box is used as the first sample point region. There are multiple first candidate bounding boxes containing all the first sample measurement points in the first coordinate space. The first target bounding box is usually the first candidate bounding box with the smallest area. The contour of the first target bounding box can be circular, rectangular or other shapes. The specific determination method of the first sample point region in the embodiments of the present application is not limited.

[0222] Similarly, the specific process of determining the second sample point region is described in detail below.

[0223] First, the state of the qubit is set to the second state;

[0224] Then, by measuring the input terminal to input a microwave signal with a specific signal frequency, the amplification circuit can absorb photons when the qubit is in the second state;

[0225] Then, the corresponding second sample voltage signal is obtained through the measurement of the output terminal. The second sample voltage signal is used to indicate that the amplification circuit can absorb photons when the qubit is in the second state;

[0226] Then, corresponding signal processing is performed on the second sample voltage signal to obtain the corresponding second phase and second amplitude. The second sample voltage signal can be demodulated, sampled and restored. The phase of the restored result is used as the second phase, and the amplitude of the restored result is used as the second amplitude;

[0227] For example, based on the Fourier transform, the second sample voltage signal in the time domain is converted to the frequency domain, and the phase and amplitude of each frequency component can be determined in the frequency domain;

[0228] Then, according to the second phase and the second amplitude, the corresponding second sample measurement points are determined in the above-mentioned first coordinate space. Therefore, the second sample measurement points are used to indicate that the amplification circuit can absorb photons when the qubit is in the second state;

[0229] For example, assuming that the position of the polar coordinate system is O and the position of the second sample measurement point is B, the length of the line segment OB is the second amplitude, and the angle between the line segment OB and the polar axis is the second phase. The polar coordinate system can also be converted into a rectangular coordinate system. The abscissa of the rectangular coordinate system is used to represent the I value (in-phase), and the ordinate of the rectangular coordinate system is used to represent the Q value (quadrature);

[0230] Then, through multiple measurements, a plurality of second sample measurement points are determined in the first coordinate space;

[0231] Then, according to the region where the plurality of second sample measurement points are located in the first coordinate space, a second sample point region is determined;

[0232] For example, a second target bounding box that contains all the second sample measurement points is determined in the first coordinate space, and the region within the second target bounding box is used as the second sample point region. There are multiple second candidate bounding boxes in the first coordinate space that contain all the second sample measurement points. The second target bounding box is usually the second candidate bounding box with the smallest area. The contour of the second target bounding box can be circular, rectangular, or other shapes. The embodiments of the present application do not limit the specific determination method of the second sample point region.

[0233] Specifically, referring to Figure 11 , Figure 11 is an optional coordinate space schematic diagram of the first sample point region and the second sample point region provided by the embodiments of the present application.

[0234] Among them, in the first coordinate space, the abscissa of the first coordinate space represents the I value, the ordinate of the first coordinate space represents the Q value. The first target bounding box of the first sample point region is circular, the second target bounding box of the second sample point region is circular. The first sample point region can contain multiple first sample measurement points, the second sample point region can contain multiple second sample measurement points, and there is no overlapping region between the first sample point region and the second sample point region.

[0235] Specifically, referring to Figure 12 , Figure 12 is an optional change curve schematic diagram of the device frequency and magnetic flux provided by the embodiments of the present application.

[0236] Among them, in the second coordinate space, the abscissa of the second coordinate space represents the magnetic flux of the amplifier circuit, the ordinate of the second coordinate space represents the device frequency of the amplifier circuit. When the device frequency of the amplifier circuit changes with the magnetic flux, at a certain magnetic flux, the device frequency jumps, indicating that the state of the amplifier circuit has transitioned to another frequency. At this time, the transformation curve of the device frequency and the magnetic flux will be divided into two branches. The measurement points corresponding to the left branch are located in the left potential well, and the measurement points corresponding to the right branch are located in the right potential well. Therefore, the measurement points corresponding to the left branch can be defined as the first sample measurement points, that is, the qubit is determined to be in the first state through the points on the left branch, and the measurement points corresponding to the right branch are defined as the second sample measurement points, that is, the qubit is determined to be in the second state through the points on the right branch.

[0237] In a possible implementation, the signal frequency of the microwave signal is determined. Specifically, curve data of the device frequency of the amplification circuit changing with the magnetic flux of the amplification circuit can be obtained. The curve data includes a first change curve corresponding to a first state and a second change curve corresponding to a second state. The first change curve and the second change curve are located in the same second coordinate space. The target frequency corresponding to the intersection point between the first change curve and the second change curve is obtained. The signal frequency of the microwave signal is determined by the difference between the target frequency and a preset value, or the signal frequency of the microwave signal is determined within the frequency range including the target frequency.

[0238] Wherein, under the action of the coupling end, a capacitance module, a second linear inductor module, and a Josephson junction in the amplification circuit form a resonant circuit. The quantum circuit can be provided with a magnetic flux bias line composed of a third linear inductor module and a current input end. Then, the magnetic flux bias line is used to bias the resonant circuit to adjust the resonant frequency of the resonant circuit, so that the amplification circuit can absorb photons when the qubit is in the second state, and the amplification circuit does not absorb photons when the qubit is in the first state.

[0239] Specifically, referring to Figure 13 , Figure 13 is an optional coordinate space schematic diagram of the target frequency provided by the embodiments of the present application.

[0240] Wherein, when adjusting the device frequency of the amplification circuit by using the magnetic flux bias line, the device frequency of the amplification circuit can be adjusted by forward scanning or reverse scanning, and there are two cases.

[0241] Case 1: The qubit is set to the first state, and the device frequency of the amplification circuit is adjusted by forward scanning. The device frequency of the amplification circuit will gradually decrease. Then, the qubit is set to the second state, and the device frequency of the amplification circuit is adjusted by reverse scanning. The device frequency of the amplification circuit will gradually increase.

[0242] Case 2: The qubit is set to the first state, and the device frequency of the amplification circuit is adjusted by forward scanning. The device frequency of the amplification circuit will gradually increase. Then, the qubit is set to the second state, and the device frequency of the amplification circuit is adjusted by reverse scanning. The device frequency of the amplification circuit will gradually decrease.

[0243] When determining the signal frequency of the microwave signal, first, the qubit is set to the first state, and then the device frequency of the amplification circuit is adjusted by forward scanning. During the adjustment process, the magnetic flux state of the amplification circuit is read, and then the first change curve of the device frequency of the amplification circuit changing with the magnetic flux of the amplification circuit is obtained.

[0244] Then, set the qubit to the second state, and then adjust the device frequency of the amplifier circuit by reverse scanning. During the adjustment process, read the magnetic flux state of the amplifier circuit, and then obtain the second variation curve of the device frequency of the amplifier circuit with respect to the magnetic flux of the amplifier circuit;

[0245] Then, place the first variation curve and the second variation curve in the same second coordinate space. The abscissa of the second coordinate space represents the magnetic flux of the amplifier circuit, and the ordinate of the second coordinate space represents the device frequency of the amplifier circuit. There is an intersection point between the first variation curve and the second variation curve in the second coordinate space. Take the device frequency corresponding to the intersection point as the target frequency.

[0246] Based on this, the target frequency or the device frequency near the target frequency can be determined as the signal frequency of the microwave signal. Specifically, the device frequency obtained by subtracting a preset value from the target frequency can be used as the signal frequency of the microwave signal. The preset value can be a zero value, or a frequency value with a positive sign, or a frequency value with a negative sign. When the preset value is a zero value, the signal frequency of the microwave signal is the target frequency. When the preset value is a frequency value with a positive sign, the signal frequency of the microwave signal is lower than the target frequency. When the preset value is a frequency value with a negative sign, the signal frequency of the microwave signal is higher than the target frequency; alternatively, a frequency interval containing the target frequency can be determined first based on the target frequency. For example, add the target frequency and a preset first distance value to obtain the frequency upper limit, and subtract the target frequency and a preset second distance value to obtain the frequency lower limit. Then, determine the frequency interval according to the frequency upper limit and the frequency lower limit, and then randomly select a device frequency in the frequency interval as the signal frequency of the microwave signal, so that the amplifier circuit can absorb photons when the qubit is in the second state, and the amplifier circuit does not absorb photons when the qubit is in the first state.

[0247] In a possible implementation manner, determine the target phase and the target amplitude according to the target voltage signal. Specifically, demodulate the target voltage signal to obtain a demodulated voltage signal; sample the demodulated voltage signal to obtain a sampled voltage signal; restore the sampled voltage signal to obtain a restored voltage signal; determine the phase of the restored voltage signal as the target phase, and determine the amplitude of the restored voltage signal as the target amplitude.

[0248] Based on this, the target voltage signal is demodulated to obtain a demodulated voltage signal. The demodulation process may include a filtering operation to filter out noise signals of specific frequencies, thereby reducing the noise and interference of the target voltage signal. Then, the demodulated voltage signal is sampled. Sampling means discretizing the demodulated voltage signal that is continuous in the time domain to obtain a sampled voltage signal. Then, the sampled voltage signal is restored. Restoration means reconstructing the continuous representation of the discrete sampled voltage signal, equivalent to restoring it back to the original voltage signal to obtain a restored voltage signal. Then, the phase of the restored voltage signal is determined as the target phase, and the amplitude of the restored voltage signal is determined as the target amplitude, which can improve the accuracy of the target measurement point and thus accurately determine the state of the qubit.

[0249] The following details the complete process of the method for measuring the state of a qubit.

[0250] Specifically, refer to Figure 14 , Figure 14 which is an optional schematic diagram of the architecture of the method for measuring the state of a qubit provided by an embodiment of the present application.

[0251] Among them, the processor for executing the method for measuring the state of a qubit can be set in a computer. In addition, the processor can also be integrated into the aforementioned chip structure, and the chip structure includes a quantum circuit, and the processor is connected to the measurement output end in the quantum circuit.

[0252] First, curve data of the device frequency of the amplifier circuit changing with the magnetic flux of the amplifier circuit is obtained. Among them, the curve data includes a first change curve corresponding to a first state and a second change curve corresponding to a second state, and the first change curve and the second change curve are located in the same second coordinate space.

[0253] Then, the target frequency corresponding to the intersection point between the first change curve and the second change curve is obtained.

[0254] Then, the difference between the target frequency and a preset value is determined as the signal frequency of the microwave signal, or the signal frequency of the microwave signal is determined within the frequency range including the target frequency.

[0255] Then, the state of the qubit is set to the first state. Whenever a microwave signal with the signal frequency is input to the measurement input end, the first sample voltage signal output each time by the measurement output end is obtained, the first sample measurement point corresponding to the first sample voltage signal in the first coordinate space is determined, and the first sample point region is obtained according to a plurality of first sample measurement points.

[0256] Then, set the state of the qubit to the second state. Whenever a microwave signal with the input signal frequency is input to the measurement input terminal, obtain the second sample voltage signal output each time at the measurement output terminal, determine the second sample measurement points corresponding to the second sample voltage signal in the first coordinate space, and obtain the second sample point region based on the multiple second sample measurement points.

[0257] Then, when a microwave signal is input to the measurement input terminal, obtain the target voltage signal output at the measurement output terminal.

[0258] Then, determine the target phase and the target amplitude based on the target voltage signal.

[0259] Then, demodulate the target voltage signal to obtain the demodulated voltage signal.

[0260] Then, sample the demodulated voltage signal to obtain the sampled voltage signal.

[0261] Then, restore the sampled voltage signal to obtain the restored voltage signal.

[0262] Then, determine the phase of the restored voltage signal as the target phase and determine the amplitude of the restored voltage signal as the target amplitude.

[0263] Then, obtain the preset first sample point region and the second sample point region in the first coordinate space, where the first sample point region and the second sample point region are respectively used to indicate two different states of the qubit.

[0264] Then, determine the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region.

[0265] Based on this, when measuring the state of the qubit, by determining the target phase and the target amplitude according to the target voltage signal, determining the target measurement point in the corresponding first coordinate space according to the target phase and the target amplitude, obtaining the preset first sample point region and the second sample point region in the first coordinate space, and determining the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region, it is possible to quickly determine the state of the qubit in a coordinate matching manner based on the first sample point region and the second sample point region, thereby effectively improving the measurement efficiency of the qubit state.

[0266] It can be understood that although the steps in the above-mentioned various flowcharts are sequentially shown according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this embodiment, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least a part of the steps in the above-mentioned flowchart may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of the steps or stages in other steps or other steps.

[0267] Referring to Figure 15 , Figure 15 , which is an optional structural schematic diagram of the measurement device for the quantum bit state provided by the embodiment of the present application. The measurement device 1500 for the quantum bit state is connected to the measurement output end in the above-mentioned quantum circuit. The measurement device 1500 for the quantum bit state includes:

[0268] A first acquisition module 1501, configured to acquire a target voltage signal output by the measurement output end when a microwave signal is input to the measurement input end;

[0269] A signal processing module 1502, configured to determine a target phase and a target amplitude according to the target voltage signal, and determine a target measurement point in the corresponding first coordinate space according to the target phase and the target amplitude;

[0270] A second acquisition module 1503, configured to acquire a preset first sample point region and a second sample point region in the first coordinate space, where the first sample point region and the second sample point region are respectively used to indicate two different states of the quantum bit;

[0271] A state determination module 1504, configured to determine the state of the quantum bit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region.

[0272] Furthermore, the measurement device further includes:

[0273] A frequency determination module (not shown in the figure), configured to determine the signal frequency of the microwave signal;

[0274] A first measurement module (not shown in the figure), configured to set the state of the quantum bit to the first state. Whenever a microwave signal with the signal frequency is input to the measurement input end, acquire the first sample voltage signal output by the measurement output end each time, determine the first sample measurement point corresponding to the first sample voltage signal in the first coordinate space, and obtain the first sample point region according to multiple first sample measurement points;

[0275] A second measurement module (not shown in the figure) is configured to set the state of the qubit to a second state. Whenever a microwave signal with the input signal frequency is input to the measurement input terminal, it acquires the second sample voltage signal output each time at the measurement output terminal, determines the second sample measurement points corresponding to the second sample voltage signal in the first coordinate space, and obtains a second sample point region based on multiple second sample measurement points.

[0276] Furthermore, the above frequency determination module is specifically configured to:

[0277] Acquire curve data of the device frequency of the amplification circuit changing with the magnetic flux of the amplification circuit, where the curve data includes a first change curve corresponding to the first state and a second change curve corresponding to the second state, and the first change curve and the second change curve are located in the same second coordinate space;

[0278] Acquire the target frequency corresponding to the intersection point between the first change curve and the second change curve;

[0279] Determine the signal frequency of the microwave signal based on the difference between the target frequency and a preset value, or determine the signal frequency of the microwave signal within a frequency interval containing the target frequency.

[0280] Furthermore, the above signal processing module 1502 is specifically configured to:

[0281] Demodulate the target voltage signal to obtain a demodulated voltage signal;

[0282] Sample the demodulated voltage signal to obtain a sampled voltage signal;

[0283] Restore the sampled voltage signal to obtain a restored voltage signal;

[0284] Determine the phase of the restored voltage signal as the target phase and determine the amplitude of the restored voltage signal as the target amplitude.

[0285] The above measurement device 1500 for the qubit state and the measurement method for the qubit state are based on the same inventive concept. By setting a capacitor module, a second linear inductor module, and a Josephson junction to form a resonant circuit, the amplification effect of the qubit signal is achieved. On this basis, a first linear inductor module is further set to reduce the nonlinearity of the amplification circuit. While meeting the amplification requirements, the coupling between the amplification circuit and the outside is reduced, thereby reducing the energy leakage of the qubit and improving the accuracy of the measurement result. Moreover, the amplification circuit can be directly coupled to the qubit without setting other intermediate devices, thereby reducing the circuit complexity of qubit measurement.

[0286] When measuring the state of a qubit, by determining a target phase and a target amplitude according to a target voltage signal, determining a target measurement point in a corresponding first coordinate space according to the target phase and the target amplitude, obtaining a preset first sample point region and a second sample point region in the first coordinate space, and determining the state of the qubit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region, it is possible to quickly determine the state of the qubit in a coordinate matching manner based on the first sample point region and the second sample point region, thereby effectively improving the measurement efficiency of the qubit state.

[0287] The electronic device provided by an embodiment of the present application for performing the above-mentioned method for measuring the state of a qubit may be a terminal. Refer to Figure 16 , Figure 16 which is a partial structural block diagram of the terminal provided by an embodiment of the present application. The terminal includes components such as a camera assembly 1610, a memory 1620, an input unit 1630, a display unit 1640, a sensor 1650, an audio circuit 1660, a wireless fidelity (WiFi) module 1670, a processor 1680, and a power supply 1690. Those skilled in the art can understand that Figure 16 the terminal structure shown in

[0288] does not limit the terminal, and may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0289] The camera assembly 1610 can be used to collect images or videos. Optionally, the camera assembly 1610 includes a front camera and a rear camera. Generally, the front camera is disposed on the front panel of the terminal, and the rear camera is disposed on the back of the terminal. In some embodiments, there are at least two rear cameras, which are any one of a main camera, a depth camera, a wide-angle camera, and a telephoto camera, so as to implement functions such as background blurring by fusing the main camera and the depth camera, panoramic shooting by fusing the main camera and the wide-angle camera, and VR (Virtual Reality) shooting function or other fusion shooting functions.

[0289] The memory 1620 can be used to store software programs and modules. The processor 1680 executes various functional applications and data processing of the terminal by running the software programs and modules stored in the memory 1620.

[0290] The input unit 1630 can be used to receive input digital or character information, and generate key signal inputs related to the settings and function controls of the terminal. Specifically, the input unit 1630 may include a touch panel 1631 and other input devices 1632.

[0291] The display unit 1640 can be used to display the input information or the provided information, as well as various menus of the terminal. The display unit 1640 may include a display panel 1641.

[0292] The audio circuit 1660, the speaker 1661, and the microphone 1662 can provide an audio interface.

[0293] The power supply 1690 can be alternating current, direct current, a disposable battery, or a rechargeable battery.

[0294] The number of the sensors 1650 can be one or more. The one or more sensors 1650 include, but are not limited to: an acceleration sensor, a gyroscope sensor, a pressure sensor, an optical sensor, and so on. Among them:

[0295] The acceleration sensor can detect the magnitudes of the accelerations on the three coordinate axes of the coordinate system established by the terminal. For example, the acceleration sensor can be used to detect the components of the gravitational acceleration on the three coordinate axes. The processor 1680 can control the display unit 1640 to display the user interface in a landscape view or a portrait view according to the gravitational acceleration signal collected by the acceleration sensor. The acceleration sensor can also be used for collecting game or user's motion data.

[0296] The gyroscope sensor can detect the body direction and the rotation angle of the terminal. The gyroscope sensor can cooperate with the acceleration sensor to collect the 3D actions of the user on the terminal. According to the data collected by the gyroscope sensor, the processor 1680 can implement the following functions: motion sensing (such as changing the UI according to the user's tilting operation), image stabilization during shooting, game control, and inertial navigation.

[0297] The pressure sensor can be disposed on the side frame of the terminal and / or the lower layer of the display unit 1640. When the pressure sensor is disposed on the side frame of the terminal, it can detect the holding signal of the user on the terminal, and the processor 1680 can perform left / right hand recognition or quick operation according to the holding signal collected by the pressure sensor. When the pressure sensor is disposed on the lower layer of the display unit 1640, the processor 1680 can control the operable controls on the UI interface according to the pressure operation of the user on the display unit 1640. The operable controls include at least one of a button control, a scroll bar control, an icon control, and a menu control.

[0298] The optical sensor is used to collect the ambient light intensity. In one embodiment, the processor 1680 may control the display brightness of the display unit 1640 according to the ambient light intensity collected by the optical sensor. Specifically, when the ambient light intensity is high, the display brightness of the display unit 1640 is increased; when the ambient light intensity is low, the display brightness of the display unit 1640 is decreased. In another embodiment, the processor 1680 may also dynamically adjust the shooting parameters of the camera assembly 1610 according to the ambient light intensity collected by the optical sensor.

[0299] In this embodiment, the processor 1680 included in the terminal may execute the method for measuring the qubit state in the previous embodiment.

[0300] The electronic device provided in the embodiment of the present application for executing the method for measuring the qubit state may also be a server. Refer to Figure 17 , Figure 17 , which is a partial structural block diagram of the server provided in the embodiment of the present application. The server 1700 may vary greatly due to configuration or performance differences, and may include one or more central processing units (Central Processing Units, abbreviated as CPU) 1722 (for example, one or more processors) and a memory 1732, and one or more storage media 1730 for storing application programs 1742 or data 1744 (for example, one or more mass storage devices). Among them, the memory 1732 and the storage media 1730 may be transient storage or persistent storage. The program stored in the storage media 1730 may include one or more modules (not shown in the figure), and each module may include a series of instruction operations on the server 1700. Further, the central processor 1722 may be configured to communicate with the storage media 1730 and execute a series of instruction operations in the storage media 1730 on the server 1700.

[0301] The server 1700 may further include one or more power supplies 1726, one or more wired or wireless network interfaces 1750, one or more input / output interfaces 1758, and / or one or more operating systems 1741, such as Windows ServerTM, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM, etc.

[0302] The processor in the server 1700 may be used to execute the method for measuring the qubit state.

[0303] The embodiment of the present application further provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the method for measuring the qubit state in the foregoing various embodiments.

[0304] An embodiment of the present application also provides a computer program product, which includes a computer program stored in a computer-readable storage medium. A processor of a computer device reads the computer program from the computer-readable storage medium, and the processor executes the computer program, so that the computer device executes the method for measuring the state of a qubit as described above.

[0305] Terms such as "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0306] It should be understood that in the present application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (one) of the following" or a similar expression refers to any combination of these items, including any combination of single items (ones) or plural items (ones). For example, at least one (one) of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0307] It should be understood that in the description of the embodiments of the present application, the meaning of "a plurality (or a number of)" is more than two, and understandings such as greater than, less than, exceeding, etc. do not include the present number, and understandings such as above, below, within, etc. include the present number.

[0308] In several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0309] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0310] In addition, each functional unit in various embodiments of the present application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0311] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs that can store program codes.

[0312] It should also be understood that the various implementation manners provided in the embodiments of the present application can be combined arbitrarily to achieve different technical effects.

[0313] The above is a specific description of the preferred embodiment of the present application. However, the present application is not limited to the above-mentioned implementation manners. Those skilled in the art can also make various equivalent deformations or substitutions without departing from the spirit of the present application. These equivalent deformations or substitutions are all included within the scope defined by the claims of the present application.

Claims

1. A quantum circuit, characterized in that, It includes qubits, an amplifying circuit, a grounding terminal, a coupling terminal, a measurement input terminal, and a measurement output terminal. The amplifying circuit includes a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction; One end of the capacitor module is connected to the coupling terminal, and the other end of the capacitor module is connected to the grounding terminal; One end of the first linear inductor module is connected to the coupling terminal, the other end of the first linear inductor module is connected to one end of the second linear inductor module, and the other end of the second linear inductor module is connected to the grounding terminal; The Josephson junction is connected in parallel across the two ends of the second linear inductor module; The qubit, the measurement input terminal, and the measurement output terminal are respectively coupled to the corresponding coupling terminal; Among them, the measurement input terminal is used to input a microwave signal, the measurement output terminal is used to output a voltage signal, and the voltage signal is used to indicate the state of the qubit.

2. The quantum circuit according to claim 1, wherein The number of the amplifying circuits and the coupling terminals is two. The two amplifying circuits share the same Josephson junction. The capacitor modules and the first linear inductor modules of each amplifying circuit are respectively connected to their corresponding coupling terminals.

3. The quantum circuit according to claim 2, wherein The two amplifying circuits include a first amplifying circuit and a second amplifying circuit. The two coupling terminals include a first coupling terminal and a second coupling terminal. The two amplifying circuits also share the same second linear inductor module; One end of the capacitor module in the first amplifying circuit is connected to the first coupling terminal, and the other end of the capacitor module in the first amplifying circuit is connected to the grounding terminal; One end of the capacitor module in the second amplifying circuit is connected to the second coupling terminal, and the other end of the capacitor module in the second amplifying circuit is connected to the grounding terminal; One end of the first linear inductor module in the first amplifying circuit is connected to the first coupling terminal, and one end of the first linear inductor module in the second amplifying circuit is connected to the second coupling terminal; One end of the second linear inductor module is respectively connected to the other end of the first linear inductor module in the first amplifying circuit and the other end of the first linear inductor module in the second amplifying circuit, and the other end of the second linear inductor module is connected to the grounding terminal.

4. The quantum circuit according to claim 2, wherein The two amplifying circuits include a first amplifying circuit and a second amplifying circuit. The two coupling terminals include a first coupling terminal and a second coupling terminal; One end of the capacitor module in the first amplifying circuit is connected to the first coupling terminal, and the other end of the capacitor module in the first amplifying circuit is connected to the grounding terminal; One end of the capacitor module in the second amplifying circuit is connected to the second coupling terminal, and the other end of the capacitor module in the second amplifying circuit is connected to the grounding terminal; One end of the first linear inductor module in the first amplifying circuit is connected to the first coupling terminal, the other end of the first linear inductor module in the first amplifying circuit is connected to one end of the second linear inductor module in the first amplifying circuit, and the other end of the second linear inductor module in the first amplifying circuit is connected to the grounding terminal; One end of the first linear inductor module in the second amplifier circuit is connected to the second coupling end, the other end of the first linear inductor module in the second amplifier circuit is connected to one end of the second linear inductor module in the second amplifier circuit, and the other end of the second linear inductor module in the second amplifier circuit is connected to the ground end.

5. The quantum circuit according to claim 1, characterized in that, The quantum circuit further includes a third linear inductor module and a current input terminal for inputting current to the third linear inductor module. The third linear inductor module is mutually inductively connected with the second linear inductor module, and the third linear inductor module is connected to the current input terminal.

6. The quantum circuit according to any one of claims 1 to 5, characterized in that, The capacitor module includes distributed capacitors, and the amplifier circuit is fabricated using planar technology.

7. An amplifying device, characterized in that, Comprising an amplifier circuit, a ground end, and a coupling end, the amplifier circuit includes a capacitor module, a first linear inductor module, a second linear inductor module, and a Josephson junction; One end of the capacitor module is connected to the coupling end, and the other end of the capacitor module is connected to the ground end; One end of the first linear inductor module is connected to the coupling end, the other end of the first linear inductor module is connected to one end of the second linear inductor module, and the other end of the second linear inductor module is connected to the ground end; The Josephson junction is connected in parallel across the two ends of the second linear inductor module.

8. A chip structure, characterized in that, Comprising: The quantum circuit according to any one of claims 1 to 6, or an amplifier device including claim 7.

9. A method for measuring the state of a qubit, characterized in that, Applied to a processor, the processor is connected to the measurement output terminal in the quantum circuit according to any one of claims 1 to 6, and the measurement method includes: When a microwave signal is input to the measurement input terminal, obtaining a target voltage signal output from the measurement output terminal; Determining a target phase and a target amplitude according to the target voltage signal, and determining a target measurement point in a corresponding first coordinate space according to the target phase and the target amplitude; Obtaining a preset first sample point region and a second sample point region in the first coordinate space, wherein the first sample point region and the second sample point region are respectively used to indicate two different states of the quantum bit; Determining the state of the quantum bit according to the attribution relationship between the target measurement point and the first sample point region or the second sample point region.

10. The measuring method according to claim 9, characterized in that, Before the step of when a microwave signal is input to the measurement input terminal and obtaining a target voltage signal output from the measurement output terminal, the measurement method further includes: Determining the signal frequency of the microwave signal; Setting the state of the quantum bit to a first state. Whenever a microwave signal with the signal frequency is input to the measurement input terminal, obtaining a first sample voltage signal output from the measurement output terminal each time, determining a first sample measurement point corresponding to the first sample voltage signal in the first coordinate space, and obtaining the first sample point region according to multiple first sample measurement points; Set the state of the qubit to the second state. Whenever the measurement input terminal is input with the microwave signal of the signal frequency, obtain the second sample voltage signal output by the measurement output terminal each time, determine the second sample measurement point corresponding to the second sample voltage signal in the first coordinate space, and obtain the second sample point region according to a plurality of the second sample measurement points.

11. The measuring method according to claim 10, characterized in that, The determining of the signal frequency of the microwave signal includes: Obtain the curve data of the device frequency of the amplifier circuit changing with the magnetic flux of the amplifier circuit, where the curve data includes a first change curve corresponding to the first state and a second change curve corresponding to the second state, and the first change curve and the second change curve are located in the same second coordinate space; Obtain the target frequency corresponding to the intersection point between the first change curve and the second change curve; Determine the signal frequency of the microwave signal by the difference between the target frequency and a preset value, or determine the signal frequency of the microwave signal in the frequency interval including the target frequency.

12. The measurement method according to claim 9, characterized in that, The determining of the target phase and the target amplitude according to the target voltage signal includes: Demodulate the target voltage signal to obtain a demodulated voltage signal; Sample the demodulated voltage signal to obtain a sampled voltage signal; Restore the sampled voltage signal to obtain a restored voltage signal; Determine the phase of the restored voltage signal as the target phase, and determine the amplitude of the restored voltage signal as the target amplitude.

13. A measuring device for the state of a qubit, characterized in that, The measurement device is connected to the measurement output terminal in the quantum circuit according to any one of claims 1 to 6, and the measurement device includes: A first acquisition module, configured to obtain the target voltage signal output by the measurement output terminal when the measurement input terminal is input with a microwave signal; A signal processing module, configured to determine the target phase and the target amplitude according to the target voltage signal, and determine the target measurement point in the corresponding first coordinate space according to the target phase and the target amplitude; A second acquisition module, configured to obtain a preset first sample point region and a second sample point region in the first coordinate space, where the first sample point region and the second sample point region are respectively used to indicate two different states of the qubit; A state determination module, configured to determine the state of the qubit according to the belonging relationship between the target measurement point and the first sample point region or the second sample point region.

14. An electronic device, comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, the measurement method according to any one of claims 9 to 12 is implemented.

15. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, the measurement method according to any one of claims 9 to 12 is implemented.

16. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, the measurement method according to any one of claims 9 to 12 is implemented.

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