Superconducting qubit inter-coupling system based on a floating coupler and methods of use, superconducting quantum processor

Abstract

The application discloses a superconducting quantum bit inter-coupling system based on a floating coupler, a use method thereof and a superconducting quantum processor. The system comprises a first superconducting quantum bit structure which is composed of a superconducting quantum interference device and a capacitor in parallel, and contains a first ground junction and a first non-ground junction; a second superconducting quantum bit structure which is composed of a superconducting quantum interference device and a capacitor in parallel, and contains a second ground junction and a second non-ground junction; and a floating coupler which contains a third junction and a fourth junction, the third junction is grounded through a fifth capacitor, the fourth junction is grounded through a sixth capacitor, and the fifth capacitor is equivalent to the sixth capacitor. The application improves the stability of the quantum processor and improves the overall processing efficiency.

Description

Technical Field

[0001] This application relates to superconducting quantum processing technology, and more particularly to a superconducting quantum bit coupling system based on a floating coupler, a method of using the system, and a superconducting quantum processor. Background Technology

[0002] Quantum computing is a novel computing paradigm based on the principles of quantum mechanics. Its core objective is to overcome the performance bottlenecks of classical computing by leveraging properties such as quantum superposition and entanglement. Traditional computers use binary bits (0 or 1) as information units, while quantum computers achieve parallel information processing through qubits. The superposition state of a qubit allows multiple states to be represented simultaneously, while quantum entanglement creates strong correlations between multiple bits, thereby achieving exponential speedups in specific tasks.

[0003] Superconducting quantum computing is one of the closest to practical application of quantum computing. Its core device is the superconducting Josephson junction, which constructs qubits through the nonlinear resonant properties of superconducting circuits. The design of superconducting circuits is highly compatible with semiconductor processes, facilitating high-density integration and large-scale scaling, and is considered a mainstream technology for realizing universal quantum computers. As a core technology for large-scale quantum computing, the key challenge of superconducting quantum computing lies in achieving high-fidelity, scalable qubit coupling and manipulation. Two-qubit gates are fundamental to quantum logic operations. Superconducting Josephson junctions can act as tunable frequency couplers to connect qubits, enabling the switching of two-qubit gates. To realize the potential of quantum computing, the system needs a sufficiently low error rate; otherwise, noise and errors will render quantum algorithms ineffective. Therefore, long-running quantum algorithms require quantum error correction, which necessitates a large number of physical qubits, making the construction of quantum computing hardware extremely challenging. Superconducting qubits, due to their fast operating speed and ease of fabrication, are a promising platform. However, scaling to more qubits introduces challenges such as manufacturing yield, frequency collisions, and chip-level correlation errors. Summary of the Invention

[0004] This application provides a superconducting quantum bit coupling system based on a floating coupler, a method for using the system, and a superconducting quantum processor, to at least solve the above-mentioned technical problems existing in the prior art.

[0005] According to a first aspect of this application, a superconducting quantum bit coupling system based on a floating coupler is provided, comprising:

[0006] The first superconducting quantum bit structure consists of a superconducting quantum interference device connected in parallel with a capacitor, and includes a first grounded node and a first ungrounded node;

[0007] The second superconducting quantum bit structure consists of a superconducting quantum interference device connected in parallel with a capacitor, and includes a second grounded node and a second ungrounded node;

[0008] A floating coupler comprising a third node and a fourth node, the third node being grounded via a fifth capacitor and the fourth node being grounded via a sixth capacitor, the fifth capacitor being equivalent to the sixth capacitor;

[0009] Wherein, there is no direct capacitive coupling between the first superconducting quantum bit structure and the second superconducting quantum bit structure; the first ungrounded node is coupled to the third node through a first capacitor, and the first ungrounded node is coupled to the fourth node through a second capacitor; the second ungrounded node is coupled to the third node through a third capacitor, and the second ungrounded node is coupled to the fourth node through a fourth capacitor.

[0010] In some alternative embodiments, the floating coupler is a frequency-tunable Transmon-type superconducting quantum bit structure, which consists of a superconducting quantum interference device connected in parallel with a capacitor.

[0011] In some alternative embodiments, both the first superconducting quantum bit structure and the second superconducting quantum bit structure are tunable frequency Transmon type superconducting quantum bit structures.

[0012] In some alternative implementations, the effective coupling strength between the first superconducting qubit structure and the second superconducting qubit structure has the opposite sign to the direct coupling strength.

[0013] In some alternative implementations, the system is configured to be enabled as a first line configuration, wherein,

[0014] The first capacitor C 12 With the second capacitor C 13 Satisfying relation (-C) 12 + C 13 )<0;

[0015] The third capacitor C 24 With the fourth capacitor C 34 Satisfying relation (C) 24 -C 34 )<0;

[0016] The operating frequencies of both the first and second superconducting qubit structures are greater than the operating frequency of the floating coupler.

[0017] In some alternative implementations, the system is configured as a second line configuration enabled, wherein:

[0018] The first capacitor C12 With the second capacitor C 13 Satisfying relation (-C) 12 + C 13 )<0;

[0019] The third capacitor C 24 With the fourth capacitor C 34 Satisfying relation (C) 24 -C 34 )>0;

[0020] The operating frequencies of the first and second superconducting qubit structures are both lower than the operating frequency of the floating coupler.

[0021] In some alternative implementations, the superconducting magnetic flux quantum of the system is: , Let be Planck's constant, and be the nodal magnetic flux in the circuit of the system. Define the reduced nodal flux. The capacitance matrix of the line is determined using the row vector of the reduced nodal flux as the basis vector. ,as follows:

[0022]

[0023] C1 is the series capacitance in the first superconducting quantum bit structure, and C2 is the series capacitance in the first superconducting quantum bit structure. This is the capacitance of the coupler node to ground;

[0024] The Hamiltonian of the line is: ;in, , yes The dual momentum operator satisfies the commutation relation: ; ;

[0025] It is the charging energy of the first superconducting quantum bit structure. , is a positive value It is the Josephson energy of the first superconducting qubit structure, and it is a positive value; It is the inverse of the capacitance matrix C;

[0026] It is the charging energy of the second superconducting quantum bit structure. , is a positive value It is the Josephson energy of the second superconducting qubit structure, and is positive;

[0027] It is the charging energy of the coupler. , is a positive value It is the Josephson energy of the coupler, and it is a positive value;

[0028] It is the coupling energy between the first superconducting qubit structure and the second superconducting qubit structure.

[0029] ,

[0030] It is a positive value;

[0031] It is the coupling energy of the first superconducting quantum bit structure and coupler. ;

[0032] It is the coupling energy between the second superconducting quantum bit structure and the coupler. ;

[0033] Using the following transformation: and For k=1,2,c, according to the Schrieffer-Wolf transform, the Hamiltonian is approximately two terms. The diagonal terms are: ;in It is the frequency of the quantum bit or coupler. , It is an anharmonic quantity of a quantum bit or coupler; , It is the detuning quantity between the quantum bit j and the coupler. , It is the sum of the frequency of the qubit j and the frequency of the coupler: , is a positive value;

[0034] Interaction term ,in It is the strength of the direct interaction between the first and second superconducting qubit structures. , is a positive value; among them, It is the strength of the indirect interaction generated between the first and second superconducting qubit structures through the coupler. ;in, , 。

[0035] According to a second aspect of this application, a method for using a superconducting quantum bit coupling system based on a floating coupler is provided, comprising:

[0036] The frequency of the floating coupler is adjusted by changing the magnetic flux applied to the superconducting quantum interference device, thereby changing its frequency relative to the first superconducting quantum bit structure and the frequency of the second superconducting quantum bit structure.

[0037] Enable or disable the effective coupling between the first superconducting quantum bit structure and the second superconducting quantum bit structure.

[0038] In some alternative implementations, the method further includes:

[0039] The frequency of the floating coupler is adjusted to a set value so that the sum of the effective coupling strength and the direct coupling strength between the first superconducting qubit structure and the second superconducting qubit structure is approximately zero, thereby putting the two qubit gates in a closed state.

[0040] According to a third aspect of this application, a superconducting quantum processor is provided, comprising a plurality of the aforementioned superconducting quantum bit coupling systems based on floating couplers.

[0041] This application discloses a superconducting quantum bit coupling system and its usage method based on floating couplers, as well as a superconducting quantum processor. Both the superconducting quantum bit structure and the floating coupler are modular designs. The superconducting quantum bit structure and the floating coupler are connected via basic components such as capacitors, enabling compatibility with various application scenarios. The distance between the superconducting quantum bit structures in this application can be relatively large. Two types of superconducting quantum bit structures can correspond to cases where the coupler frequency is higher than the quantum bit frequency and cases where the coupler frequency is lower than the quantum bit frequency, respectively. The coupler is a frequency-tunable transmon superconducting quantum bit, consisting of a superconducting quantum interference device (SQU) connected in parallel with a capacitor. The coupler uses a floating coupler, making it ungrounded. The Josephson energy of the SQU can be adjusted by changing the magnetic flux passing through the SQU. This application ensures the precise representation of the superconducting quantum bits, improves the stability of the quantum processor, and enhances the overall processing efficiency.

[0042] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0043] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings. Several embodiments of this application are illustrated in the drawings by way of example and not limitation, in which:

[0044] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0045] Figure 1 A circuit diagram showing the superconducting quantum bit and its coupler connection is shown;

[0046] Figure 2 A schematic diagram of the composition structure of a superconducting quantum bit coupling system based on a floating coupler according to an embodiment of this application is shown;

[0047] Figure 3 A schematic diagram of the first circuit configuration of a superconducting quantum bit coupling system based on a floating coupler according to an embodiment of this application is shown;

[0048] Figure 4 A schematic diagram of the second circuit configuration of the superconducting quantum bit coupling system based on a floating coupler according to an embodiment of this application is shown;

[0049] Figure 5 A schematic diagram of the composition structure of an electronic device according to an embodiment of this application is shown. Detailed Implementation

[0050] To make the objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] Currently, tunable couplers can be used to achieve coupling between superconducting qubits, thereby realizing the switching of a two-qubit gate. The technical solution is as follows: two grounded transmon superconducting qubits are capacitively coupled to a tunable frequency grounded coupler. The coupler is a superconducting quantum interference device, and its frequency can be adjusted by changing the magnetic field passing through the superconducting quantum interference device. By adjusting the frequency of the coupler, this scheme can effectively realize the switching of a two-qubit gate. In addition, this scheme can meet the requirements of qubit scaling. Through theoretical derivation, this scheme has the following conditions that must be met: (1) The frequency of the coupler must be higher than the frequencies of the two superconducting qubits. (2) The two superconducting qubits must have direct capacitive coupling. Figure 1 A circuit diagram showing superconducting qubits and their coupler connections is shown, as follows: Figure 1 As shown, the circuit model includes qubit structure 1 and qubit structure 2, which are connected to the coupler via corresponding capacitors.

[0052] Figure 1The main drawback of the illustrated technical solution is its difficulty in meeting the modular requirements of superconducting qubits. Because the superconducting qubit structures of different superconducting qubit modules are far apart, their direct capacitive coupling is extremely small. Since existing solutions require direct capacitive coupling between qubits, it is difficult to achieve compatibility with modular solutions. Furthermore, direct capacitive coupling between two qubit structures requires very close qubit spacing, making crosstalk between qubits difficult to overcome. Figure 1 The structure shown requires the coupler frequency to be higher than the quantum bit frequency, which limits the frequency range of coupler fabrication.

[0053] This application proposes a scheme for coupling between superconducting qubits using a floating coupler. The core of this scheme is that the floating coupler is an ungrounded coupler. The main advantage of this scheme is that it eliminates the need for direct capacitive coupling between qubits. Furthermore, this scheme is compatible with modular designs, and the distance between qubit structures can be set to a considerable distance.

[0054] The two configurations included in the technical solutions of this application can respectively correspond to the case where the coupler frequency is greater than the quantum bit frequency and the case where the coupler frequency is less than the quantum bit frequency.

[0055] First, let's declare some constants used. Imaginary unit: Planck's constant: Reduce Planck's constant: Unit charge: Superconducting flux quantum: For the nodal magnetic flux in the circuit Define the reduced nodal flux. For ease of description, reduced magnetic flux is used throughout the embodiments of this application.

[0056] The circuit model in this application embodiment is as follows: Figure 2 As shown, the first superconducting quantum bit structure 1 and the coupler are capacitively coupled, and the second superconducting quantum bit structure 2 and the coupler are capacitively coupled. The two nodes of the coupler are not grounded. There is no direct capacitive coupling between the first superconducting quantum bit structure 1 and the second superconducting quantum bit structure 2.

[0057] In this embodiment, the first superconducting quantum bit structure 1 has two nodes, one grounded and the other denoted as node 1. Node 1 has a reduced node magnetic flux. The first superconducting qubit structure is a tunable frequency transmon superconducting qubit, which consists of a superconducting quantum interference device connected in parallel with a capacitor. The capacitance of the parallel capacitor is... The Josephson energy of the superconducting quantum interference device here is . The magnitude of the flux can be controlled by adjusting the change in magnetic flux through the superconducting quantum interference device. The magnetic flux can be controlled by adjusting the current in a current line. Figure 2 Not shown in the image.

[0058] The coupler has two nodes, denoted as node 2 and node 3. Node 2 has reduced nodal flux. There is reduced nodal flux at node 3. The capacitance from node 2 to ground is The capacitance from node 3 to ground is also... . and Satisfy in design For the sake of simplicity in the formula, let... . Here is the defined capacitance of the coupler node to ground. The coupler is a frequency-tunable transmon superconducting quantum bit structure, consisting of a superconducting quantum interference device connected in parallel with a capacitor. The capacitance of this parallel capacitor is... The Josephson energy of the superconducting quantum interference device here is . The magnitude of the flux can be controlled by adjusting the change in magnetic flux through the superconducting quantum interference device. The magnetic flux can be controlled by adjusting the current in a current line. Figure 2 Not shown in the image.

[0059] The second superconducting qubit structure has two nodes: one grounded and the other designated node 4. Node 4 carries a reduced node magnetic flux. The second superconducting qubit structure is a tunable frequency transmon superconducting qubit, consisting of a superconducting quantum interference device connected in parallel with a capacitor. The capacitance of this capacitor is... The Josephson energy of the superconducting quantum interference device here is . The magnitude of the flux can be controlled by adjusting the change in magnetic flux through the superconducting quantum interference device. The magnetic flux can be controlled by adjusting the current in a current line. Figure 2 Not shown in the image.

[0060] like Figure 2 As shown, the capacitance between node 1 and node 2 is The capacitance between node 1 and node 3 is The capacitance between node 2 and node 4 is The capacitance between node 3 and node 4 is .

[0061] in, , , as well as The size is on the order of 100 fF. , , , Its size is on the order of 1 to 10 fF.

[0062] The dynamic variables of the circuit are denoted as elements, and is the row vector of the reduced nodal flux: ( , , , ),in , .

[0063] The first superconducting quantum bit structure 1 and the coupler are capacitively coupled, as are the second superconducting quantum bit structure 2 and the coupler. The two nodes of the coupler are not grounded. There is no direct capacitive coupling between the first superconducting quantum bit structure 1 and the second superconducting quantum bit structure 2.

[0064] In the embodiments of this application, the necessary condition for implementing a two-bit gate switch is that and The sign is opposite, that is The same circuit model can have two different circuit configurations. The design of the qubit frequency and the coupler frequency must meet certain conditions.

[0065] like Figure 3 The diagram illustrates a first circuit configuration according to an embodiment of this application, showing the connection structure of a superconducting quantum bit structure and a coupler. The first superconducting quantum bit structure 1 is composed of a first superconducting quantum interference device 10 connected in parallel with a capacitor, and the second superconducting quantum bit structure 2 is composed of a second superconducting quantum interference device 20 connected in parallel with a capacitor. The coupler consists of two superconducting quantum interference devices 30 connected in parallel with a capacitor, and the parallel connection method is as follows: Figure 3 The superconducting quantum interference device shown is connected in parallel at approximately position 30. It satisfies... ,therefore , , . In order to make The operating frequency of the qubit structure and the operating frequency of the coupler must satisfy the following: .

[0066] The second circuit configuration is as follows: Figure 4As shown. In the second circuit configuration, the first superconducting quantum bit structure 1 is composed of a first superconducting quantum interference device 10 connected in parallel with a capacitor, and the second superconducting quantum bit structure 2 is composed of a second superconducting quantum interference device 20 connected in parallel with a capacitor; the coupler is composed of two superconducting quantum interference devices 30 connected in parallel with a capacitor, and the parallel connection method is as follows. Figure 3 The superconducting quantum interference device 30 is shown in parallel at the top and bottom positions. The second circuit configuration satisfies... ,therefore . ,therefore .therefore In order to make The frequency of the qubit and the frequency of the coupler must satisfy the following: .

[0067] Once the above parameters are determined, the capacitance matrix of the circuit can be completely determined using the row vector of the reduced nodal flux as the basis vector. ,as follows:

[0068]

[0069] |C| is the determinant of the capacitance matrix C. Since all capacitances are positive, it can be directly calculated that |C| is positive. Therefore, the capacitance matrix C is invertible. It is the inverse of the capacitance matrix C. The element in the m-th row and n-th column is denoted as .

[0070] After a standard quantization procedure, the reduced flux is transformed into a reduced flux operator, and the Hamiltonian of the circuit is: .

[0071] In this embodiment, the subscripts 1 and 2 represent the first superconducting qubit structure 1 and the second superconducting qubit structure 2, respectively, and the subscript c represents the coupler. No such subscript appears in this Hamiltonian. The reason is It is a conserved quantity. In the Hamiltonian... Hamiltonian yes The dual momentum operator satisfies the commutation relation: All operators with different subscripts commutate.

[0072] It is the charging energy of superconducting quantum bit structure 1. , which is a positive value. It is the Josephson energy of superconducting qubit structure 1, and is a positive value.

[0073] It is the charging energy of superconducting quantum bit structure 2. , which is a positive value. It is the Josephson energy of superconducting qubit structure 2, and it is a positive value.

[0074] It is the charging energy of the coupler. , which is a positive value. It is the Josephson energy of the coupler, and it is a positive value.

[0075] It is the coupling energy between the first superconducting quantum bit structure 1 and the first superconducting quantum bit structure 2.

[0076] ,

[0077] It is a positive value.

[0078] It is the coupling energy between the first superconducting quantum bit structure 1 and the coupler. Based on the order of magnitude of each capacitor, Depend on leading.

[0079] It is the coupling energy between the second superconducting quantum bit structure 2 and the coupler. Based on the order of magnitude of each capacitor, Depend on leading.

[0080] Using transformation and Given k=1,2,c, and the Schrieffer-Wolf transform and the rotating wave approximation, the Hamiltonian can be approximated by two terms, namely... The diagonal terms are: .in It is the frequency of the quantum bit or coupler. , It is an anharmonic quantity of a quantum bit or coupler. . It is the detuning quantity between the quantum bit j and the coupler. Its positive or negative sign is determined by setting the relative size of the qubit and the coupler. It is the sum of the frequency of the qubit j and the frequency of the coupler: , which is a positive value.

[0081] The interaction term is: .in It is the first superconducting quantum bit structure 1 and Second The strength of the direct interaction between the two superconducting qubit structures. , which is a positive value. It is the strength of the indirect interaction between the first superconducting quantum bit structure 1 and the second superconducting quantum bit structure 2 through the coupler. .in, , .

[0082] The necessary condition for implementing a two-bit gate switch is and The sign is opposite, that is The same circuit model can have two different circuit configurations.

[0083] This application also describes a method for using a superconducting quantum bit coupling system based on a floating coupler, including:

[0084] The frequency of the floating coupler is adjusted by changing the magnetic flux applied to the superconducting quantum interference device, thereby changing its frequency relative to the first superconducting quantum bit structure and the frequency of the second superconducting quantum bit structure.

[0085] Enable or disable the effective coupling between the first superconducting quantum bit structure and the second superconducting quantum bit structure.

[0086] In this embodiment, by adjusting the frequency of the floating coupler to a set value, the sum of the effective coupling strength and the direct coupling strength between the first superconducting quantum bit structure and the second superconducting quantum bit structure can be approximately zero, thereby keeping the two quantum bit gates in a closed state.

[0087] According to embodiments of this application, this application also describes an electronic device. Figure 5 A schematic block diagram of an example electronic device 800 that can be used to implement embodiments of this application is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device may also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the application described and / or claimed herein.

[0088] like Figure 5As shown, device 800 includes a computing unit 801, which can perform various appropriate actions and processes based on a computer program stored in read-only memory (ROM) 802 or a computer program loaded from storage unit 808 into random access memory (RAM) 803. RAM 803 may also store various programs and data required for the operation of device 800. The computing unit 801, ROM 802, and RAM 803 are interconnected via bus 804. Input / output (I / O) interface 805 is also connected to bus 804.

[0089] Multiple components in device 800 are connected to I / O interface 805, including: input unit 806, such as keyboard, mouse, etc.; output unit 807, such as various types of monitors, speakers, etc.; storage unit 808, such as disk, optical disk, etc.; and communication unit 809, such as network card, modem, wireless transceiver, etc. Communication unit 809 allows device 800 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0090] The computing unit 801 can be various general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The computing unit 801 can be the superconducting quantum processor of the embodiments of this application.

[0091] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A superconducting quantum bit coupling system based on a floating coupler, characterized in that, The system includes: The first superconducting quantum bit structure consists of a superconducting quantum interference device connected in parallel with a capacitor, and includes a first grounded node and a first ungrounded node; The second superconducting quantum bit structure consists of a superconducting quantum interference device connected in parallel with a capacitor, and includes a second grounded node and a second ungrounded node; A floating coupler comprising a third node and a fourth node, the third node being grounded via a fifth capacitor and the fourth node being grounded via a sixth capacitor, the fifth capacitor being equivalent to the sixth capacitor; Wherein, there is no direct capacitive coupling between the first superconducting quantum bit structure and the second superconducting quantum bit structure; the first ungrounded node is coupled to the third node through a first capacitor, and the first ungrounded node is coupled to the fourth node through a second capacitor; the second ungrounded node is coupled to the third node through a third capacitor, and the second ungrounded node is coupled to the fourth node through a fourth capacitor; The superconducting magnetic flux quantum of the system: , Let be Planck's constant, and be the nodal magnetic flux in the circuit of the system. Define the reduced nodal flux The capacitance matrix of the line is determined using the row vector of the reduced nodal flux as the basis vector. ,as follows: C1 is the series capacitance in the first superconducting quantum bit structure, and C2 is the series capacitance in the first superconducting quantum bit structure. C is the capacitance of the coupler node to ground. 12 For the first capacitor, C 13 For the second capacitor, C 24 For the third capacitor, C 34 This is the fourth capacitor; The Hamiltonian of the line is: ;in, , yes The dual momentum operator satisfies the commutation relation: ; ; It is the charging energy of the first superconducting quantum bit structure. , is a positive value It is the Josephson energy of the first superconducting qubit structure, and it is a positive value; It is the inverse of the capacitance matrix C; It is the charging energy of the second superconducting quantum bit structure. , is a positive value It is the Josephson energy of the second superconducting qubit structure, and is positive; It is the charging energy of the coupler. , is a positive value It is the Josephson energy of the coupler, and it is a positive value; It is the coupling energy between the first superconducting qubit structure and the second superconducting qubit structure. ， It is a positive value; It is the coupling energy of the first superconducting quantum bit structure and coupler. ; It is the coupling energy between the second superconducting quantum bit structure and the coupler. ; Using the following transformation: and For k=1,2,c, according to the Schrieffer-Wolf transform, the Hamiltonian is approximately two terms. The diagonal terms are: ;in It is the frequency of the quantum bit or coupler. , It is an anharmonic quantity of a quantum bit or coupler; , It is the detuning quantity between the quantum bit j and the coupler. , It is the sum of the frequency of the qubit j and the frequency of the coupler: , is a positive value; Interaction term ,in It is the strength of the direct interaction between the first and second superconducting qubit structures. , is a positive value; among them, It is the strength of the indirect interaction generated between the first and second superconducting qubit structures through the coupler. ;in, , .

2. The system according to claim 1, characterized in that, The floating coupler is a Transmon-type superconducting quantum bit structure with adjustable frequency, which consists of a superconducting quantum interference device connected in parallel with a capacitor.

3. The system according to claim 1 or 2, characterized in that, Both the first and second superconducting qubit structures are tunable frequency Transmon-type superconducting qubit structures.

4. The system according to claim 1, characterized in that, The effective coupling strength between the first superconducting qubit structure and the second superconducting qubit structure has the opposite sign to the direct coupling strength.

5. The system according to claim 4, characterized in that, The system is configured to be enabled as a first line configuration, wherein... The first capacitor C 12 With the second capacitor C 13 Satisfying relation (-C) 12 + C 13 ) < 0; The third capacitor C 24 With the fourth capacitor C 34 Satisfying relation (C) 24 -C 34 ) < 0; The operating frequencies of both the first and second superconducting qubit structures are greater than the operating frequency of the floating coupler.

6. The system according to claim 5, characterized in that, The system is configured to be enabled as a second line configuration, wherein: The first capacitor C 12 With the second capacitor C 13 Satisfying relation (-C) 12 + C 13 ) < 0; The third capacitor C 24 With the fourth capacitor C 34 Satisfying relation (C) 24 -C 34 ) > 0; The operating frequencies of the first and second superconducting qubit structures are both lower than the operating frequency of the floating coupler.

7. A method of using the superconducting quantum bit coupling system based on a floating coupler as described in any one of claims 1 to 6, characterized in that, The method includes: The frequency of the floating coupler is adjusted by changing the magnetic flux applied to the superconducting quantum interference device, thereby changing its frequency relative to the first superconducting quantum bit structure and the frequency of the second superconducting quantum bit structure. Enable or disable the effective coupling between the first superconducting quantum bit structure and the second superconducting quantum bit structure.

8. The method according to claim 7, characterized in that, The method further includes: The frequency of the floating coupler is adjusted to a set value so that the sum of the effective coupling strength and the direct coupling strength between the first superconducting qubit structure and the second superconducting qubit structure is approximately zero, thereby putting the two qubit gates in a closed state.

9. A superconducting quantum processor, characterized in that, The system comprises multiple superconducting quantum bit coupling systems based on floating couplers as described in any one of claims 1 to 6.

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