Superconducting qubit coupling device, superconducting quantum chip, and quantum computer

Abstract

A superconducting qubit coupling device, a superconducting quantum chip, and a quantum computer. The superconducting qubit coupling device comprises a first superconducting qubit (10), a second superconducting qubit (20), a first coupling module (40), a second coupling module (50) and an adjustable coupling module (30); the adjustable coupling module (30) comprises two resonant circuits, and the frequency of at least one of the resonant circuits is adjustable. According to the present application, the coupling strengths between the two resonant circuits of the adjustable coupling module (30) and the first superconducting qubit (10) have opposite signs and have the same or similar magnitude(s), and the coupling strengths between the two resonant circuits of the adjustable coupling module and the second superconducting qubit (20) have the same sign and have the same or similar magnitude(s). Thus, when the frequency of the first resonant circuit is the same as or close to the frequency of the second resonant circuit, the coupling between the two superconducting qubits is switched off; moreover, coupling switch-off is independent of the frequencies of the two superconducting qubits, and the two superconducting qubits have the characteristic of full-band coupling switch-off.

Description

Superconducting quantum bit coupling device, superconducting quantum chip and quantum computer

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on August 24, 2023, with application number 202311077099.0 and application name “A Superconducting Quantum Bit Coupling Device, Superconducting Quantum Chip and Quantum Computer”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of quantum computing, and in particular to a coupling device for superconducting quantum bits, a superconducting quantum chip, and a quantum computer. Background Art

[0003] Quantum computing is a new type of computing method based on quantum mechanics, leveraging properties such as quantum superposition and entanglement. In theory, quantum computing offers exponential speedups compared to classical computing for specific problems, such as factoring large numbers and quantum chemistry simulations. Superconducting qubits are currently one of the most promising physical systems for realizing quantum computing. Superconducting quantum computing is a quantum computing solution based on superconducting circuits. Superconducting circuits are microwave circuits composed of basic components such as capacitors, inductors, transmission lines, and Josephson junctions. Superconducting circuit chips operate in the ultra-low temperature environment provided by dilution refrigerators to achieve superconductivity.

[0004] In the early days of superconducting qubit development, superconducting qubits were coupled using fixed capacitive coupling or quantum buses. This design reduced circuit complexity, alleviated the burden of superconducting circuit design and micro-nanofabrication, and achieved good results. However, as the number of superconducting qubits increased, circuit scale grew. The inter-bit crosstalk caused by the fixed coupling between superconducting qubits, which could not be switched off, led to a series of difficult-to-solve problems, such as difficulty in executing single-bit logic gates simultaneously and limited fidelity of two-bit logic gate operations.

[0005] To solve these problems, some researchers have begun to turn to designing adjustable couplers for coupling bits. The introduction of adjustable couplers has indeed greatly alleviated the crosstalk problem in multi-bit systems, but it has also increased the difficulty of manipulation due to the introduction of additional degrees of freedom of manipulation. The turn-off conditions of existing adjustable couplers are all related to the frequency of the superconducting quantum bit. Any frequency adjustment of the superconducting quantum bit will require readjustment of the bias points of the surrounding couplers. In other words, if the frequency of the superconducting quantum bit changes, the turn-off condition of the coupling will not hold. Therefore, there is an urgent need for a solution that can achieve a coupling turn-off condition that is independent of the frequency of the superconducting quantum bit.

[0006] Summary of the Invention

[0007] The embodiments of the present application provide a superconducting quantum bit coupling device, a superconducting quantum chip, and a quantum computer, which simplify the adjustment method for achieving coupling and disconnection between two superconducting quantum bits, achieve full-band coupling and disconnection of two superconducting quantum bits, and provide greater freedom for frequency allocation of multiple superconducting quantum bits.

[0008] In a first aspect, an embodiment of the present application provides a coupling device for a superconducting qubit, specifically comprising: a first superconducting qubit, a second superconducting qubit, a first coupling module, a second coupling module, and an adjustable coupling module. The adjustable coupling module is coupled to the first superconducting qubit via the first coupling module, and the adjustable coupling module is coupled to the second superconducting qubit via the second coupling module. The adjustable coupling module comprises a first resonant circuit and a second resonant circuit, wherein the frequency of at least one of the first resonant circuit and the second resonant circuit is adjustable. The coupling strengths between the first resonant circuit and the second resonant circuit and the first superconducting qubit are respectively opposite in sign and the absolute values ​​of the coupling strengths are the same or similar, and the coupling strengths between the first resonant circuit and the second resonant circuit and the second superconducting qubit are respectively opposite in sign and the coupling strengths are the same or similar. By adjusting the frequency of at least one of the first resonant circuit and the second resonant circuit, when the frequency of the first resonant circuit is the same or similar to the frequency of the second resonant circuit, the coupling between the first superconducting qubit and the second superconducting qubit is turned off.

[0009] In this embodiment, only one adjustment is required to achieve the coupling and disconnection between the first superconducting qubit and the second superconducting qubit, and the coupling and disconnection are independent of the frequencies of the two superconducting qubits, which simplifies the adjustment method for achieving the coupling and disconnection between the two superconducting qubits. In other words, in the subsequent process, no matter how the frequency of the superconducting qubit changes, there is no need to change the bias point of the adjustable coupling module, thereby achieving full-band coupling and disconnection of the two superconducting qubits. Even if the frequency of the superconducting qubit changes due to the transition of the superconducting qubit to a higher energy level, the coupling and disconnection between the two superconducting qubits can still be achieved, which is beneficial to suppressing high-energy level leakage and improving the fidelity of the parallel logic gate in the coupling device of the superconducting qubit. In addition, since the coupling and disconnection between the two superconducting qubits are independent of the frequencies of the two superconducting qubits, it provides greater freedom for the frequency allocation of multiple superconducting qubits, and there is no coupling leakage problem when performing parallel gate operations in multiple bits, thus supporting high-fidelity multi-bit parallel gates.

[0010] In some possible embodiments, the first superconducting quantum bit includes a first electrode and a second electrode, both of which are not grounded. When the first superconducting quantum bit is in resonance, the voltage on the first electrode and the voltage on the second electrode are of opposite signs, which is conducive to achieving the above-mentioned coupling-off condition in which the coupling strength between the two resonant circuits of the adjustable coupling module and the first superconducting quantum bit has opposite signs and is the same or similar in magnitude.

[0011] In some possible embodiments, the first electrode includes a first capacitance to ground, the second electrode includes a second capacitance to ground, and the first capacitance to ground and the second capacitance to ground are of the same or similar magnitude, which is conducive to achieving the above-mentioned coupling-off condition in which the coupling strength between the two resonant circuits of the adjustable coupling module and the first superconducting quantum bit has opposite signs and is the same or similar magnitude.

[0012] In some possible implementations, the first electrode and the second electrode are connected via a first inductor circuit. The first inductor circuit includes at least one Josephson junction and has good practicality.

[0013] In some possible implementations, the first coupling module includes a first capacitor and a second capacitor. The first resonant circuit is coupled to the first electrode via the first capacitor, and the second resonant circuit is coupled to the second electrode via the second capacitor. The first capacitor and the second capacitor have the same or similar magnitudes, which facilitates achieving the aforementioned coupling-off condition in which the coupling strengths between the two resonant circuits of the adjustable coupling module and the first superconducting qubit have opposite signs but are the same or similar magnitudes.

[0014] In some possible implementations, a first parasitic capacitor in the first coupling module is located between the first resonant circuit and the second electrode, and a second parasitic capacitor in the first coupling module is located between the second resonant circuit and the first electrode. The first and second parasitic capacitors are of equal or similar magnitude, which facilitates achieving the aforementioned coupling-off condition in which the coupling strengths between the two resonant circuits of the adjustable coupling module and the first superconducting qubit have opposite signs and are equal or similar in magnitude.

[0015] In some possible implementations, both the first resonant circuit and the second resonant circuit are adjustable couplers. Alternatively, the first resonant circuit is an adjustable coupler, and the second resonant circuit is a fixed coupler. This implementation provides multiple implementations of the adjustable coupling module, enhancing the scalability of this solution.

[0016] In some possible implementations, the second superconducting qubit includes a third electrode, which is grounded via a second inductor circuit. The second inductor circuit includes at least one Josephson junction, and the first resonant circuit and the second resonant circuit are respectively coupled to the third electrode via a second coupling module. In other words, the second superconducting qubit can adopt a single-electrode grounding structure, which has good feasibility.

[0017] In some possible embodiments, the second coupling module includes a third capacitor and a fourth capacitor. The first resonant circuit is coupled to the third electrode of the second superconducting qubit via the third capacitor, and the second resonant circuit is coupled to the third electrode of the second superconducting qubit via the fourth capacitor. The third capacitor and the fourth capacitor have the same or similar magnitudes. For scenarios where the second superconducting qubit employs a single-electrode grounded structure, a design approach for the second coupling module is provided that facilitates achieving the aforementioned coupling-off condition in which the coupling strengths between the two resonant circuits of the adjustable coupling module and the second superconducting qubit have the same sign and are the same or similar in magnitude.

[0018] In some possible implementations, the second superconducting qubit includes a fourth electrode and a fifth electrode, both of which are ungrounded. The fourth and fifth electrodes are connected via a third inductor circuit, which includes at least one Josephson junction. The first resonant circuit and the second resonant circuit are each coupled to the fourth electrode via a second coupling module. In other words, the second superconducting qubit can also employ a dual-electrode floating structure, increasing the flexibility of this solution.

[0019] In some possible embodiments, the second coupling module includes a third capacitor and a fourth capacitor. The first resonant circuit is coupled to the fourth electrode of the second superconducting qubit via the third capacitor, and the second resonant circuit is coupled to the fourth electrode of the second superconducting qubit via the fourth capacitor. The third capacitor and the fourth capacitor have the same or similar magnitudes. For scenarios where the second superconducting qubit employs a dual-electrode floating structure, a design approach for the second coupling module is provided that facilitates achieving the aforementioned coupling-off condition in which the coupling strengths between the two resonant circuits of the adjustable coupling module and the second superconducting qubit have the same sign and are the same or similar in magnitude.

[0020] In some possible implementations, a third parasitic capacitor in the second coupling module is located between the first resonant circuit and the fifth electrode, and a fourth parasitic capacitor in the second coupling module is located between the second resonant circuit and the fifth electrode. The third and fourth parasitic capacitors have the same or similar magnitudes, which facilitates achieving the aforementioned coupling-off condition in which the coupling strengths between the two resonant circuits of the adjustable coupling module and the second superconducting qubit have the same sign and are the same or similar magnitudes.

[0021] In some possible implementations, the first resonant circuit and the second resonant circuit have a shared circuit structure, and this shared circuit structure is coupled to the second superconducting quantum bit through a second coupling module. This design of the adjustable coupling module is more conducive to achieving the above-mentioned coupling shutdown condition.

[0022] In some possible implementations, the second superconducting qubit includes a third electrode, which is grounded via a second inductor circuit. The second inductor circuit includes at least one Josephson junction, and the circuit structure shared by the first resonant circuit and the second resonant circuit is coupled to the third electrode via a second coupling module. In other words, the second superconducting qubit can employ a single-electrode grounding structure, which has good feasibility.

[0023] In some possible implementations, the second coupling module includes a fifth capacitor, and the circuit structure shared by the first resonant circuit and the second resonant circuit is coupled to the third electrode of the second superconducting qubit via the fifth capacitor. This provides another design for the second coupling module, which has a simpler structure and makes it easier to achieve a coupling-off condition.

[0024] In some possible implementations, the second superconducting qubit includes a fourth electrode and a fifth electrode, both of which are ungrounded. The fourth and fifth electrodes are connected via a third inductor circuit, which includes at least one Josephson junction. A circuit structure shared by the first and second resonant circuits is coupled to the fourth electrode via a second coupling module. In other words, the second superconducting qubit can also employ a dual-electrode floating structure, increasing the flexibility of this solution.

[0025] In some possible implementations, the second coupling module includes a fifth capacitor, and the circuit structure shared by the first and second resonant circuits is coupled to the fourth electrode of the second superconducting qubit via the fifth capacitor. This provides another design for the second coupling module, which has a simpler structure and makes it easier to achieve a coupling-off condition.

[0026] In some possible embodiments, the fifth parasitic capacitor in the second coupling module is located between the circuit structure shared by the first resonant circuit and the second resonant circuit and the fifth electrode, and the fifth parasitic capacitor is smaller than the fifth capacitor, which is conducive to achieving the above-mentioned coupling shutdown condition in which the coupling strength between the two resonant circuits of the adjustable coupling module and the second superconducting quantum bit has the same sign and the same or similar size.

[0027] In some possible implementations, at least one of the first resonant circuit and the second resonant circuit includes an adjustable inductor and / or an adjustable capacitor, and at least one of the first resonant circuit and the second resonant circuit further includes a bias circuit. The bias circuit is used to adjust the magnitude of the adjustable inductor and / or the magnitude of the adjustable capacitor, thereby ensuring that the frequency of at least one resonant circuit in the adjustable coupling module is adjustable.

[0028] In some possible implementations, the first superconducting qubit is a fixed-frequency Transmon, adjustable Transmon, Fluxonium, or a flux qubit with capacitor shunt, and the second superconducting qubit is a fixed-frequency Transmon, adjustable Transmon, Fluxonium, or a flux qubit with capacitor shunt, which expands the applicable scenarios of this solution.

[0029] In a second aspect, an embodiment of the present application provides a superconducting quantum chip, which includes a plurality of coupling devices for superconducting qubits as described in any embodiment of the first aspect. The coupling devices of the plurality of superconducting qubits are distributed in an array, and the coupling devices of every two adjacent superconducting qubits share one superconducting qubit, and the first superconducting qubit and the second superconducting qubit in the coupling device of each superconducting qubit include two ungrounded electrodes. In this superconducting quantum chip, the shared superconducting qubit is the first superconducting qubit or the second superconducting qubit in the coupling device of two adjacent superconducting qubits. Alternatively, the shared superconducting qubit is the first superconducting qubit in the coupling device of one of the superconducting qubits, and the shared superconducting qubit is the second superconducting qubit in the coupling device of another superconducting qubit.

[0030] That is to say, if the adjustable coupling module, the first coupling module, and the second coupling module in the coupling device of each superconducting qubit are collectively referred to as a coupler, then every two adjacent superconducting qubits in the superconducting quantum chip are coupled through the coupler. Moreover, for any superconducting qubit, the superconducting qubit can serve as both the first superconducting qubit and the second superconducting qubit. Therefore, for this embodiment, only one type of superconducting qubit needs to be designed, and this type of superconducting qubit can be placed in different positions to play the role of the first superconducting qubit or the second superconducting qubit, and the overall symmetry of the superconducting quantum chip is better.

[0031] In a third aspect, an embodiment of the present application provides a superconducting quantum chip, which includes a plurality of coupling devices for superconducting quantum bits as described in any embodiment of the first aspect. The coupling devices of the plurality of superconducting quantum bits are distributed in an array, and the coupling devices of each two adjacent superconducting quantum bits share one superconducting quantum bit. The first superconducting quantum bit in the coupling device of each superconducting quantum bit includes a first electrode and a second electrode, both of which are not grounded, the first electrode includes two interconnected sub-electrodes, and the second electrode includes two interconnected sub-electrodes, and the two sub-electrodes of the first electrode are placed crosswise with the two sub-electrodes of the second electrode. The shared superconducting quantum bit is the first superconducting quantum bit or the second superconducting quantum bit in the coupling device of two adjacent superconducting quantum bits.

[0032] For this embodiment, the two electrodes of the first superconducting quantum bit are designed to be four cross-distributed sub-electrodes, ensuring that the coupling device of each superconducting quantum bit sharing the first superconducting quantum bit can utilize one set of sub-electrode 1 and sub-electrode 2, and the overall symmetry of the superconducting quantum chip is good.

[0033] In a fourth aspect, an embodiment of the present application provides a quantum computer, which includes: a dilution refrigerator, a measurement and control system, and a superconducting quantum chip as described in the third aspect or the fourth aspect.

[0034] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0035] The coupling device of the superconducting qubit provided in the present application includes a first superconducting qubit, a second superconducting qubit, a first coupling module, a second coupling module and an adjustable coupling module, the adjustable coupling module includes a first resonant circuit and a second resonant circuit, and the frequency of at least one of the first resonant circuit and the second resonant circuit is adjustable. The present application is designed so that the coupling strength between the first resonant circuit and the second resonant circuit and the first superconducting qubit is opposite in sign and the absolute value of the coupling strength is the same or similar, and the coupling strength between the first resonant circuit and the second resonant circuit and the second superconducting qubit is opposite in sign and the coupling strength is the same or similar. Therefore, when the frequency of the first resonant circuit is the same as or close to the frequency of the second resonant circuit, the coupling between the first superconducting qubit and the second superconducting qubit is turned off. It can be seen that the present application only requires one adjustment to realize the coupling shutdown between the first superconducting qubit and the second superconducting qubit, and the coupling shutdown is independent of the frequency of the two superconducting qubits, which simplifies the adjustment method for realizing the coupling shutdown between the two superconducting qubits. That is to say, in the subsequent process, no matter how the frequency of the superconducting qubit changes, there is no need to change the bias point of the adjustable coupling module, thus achieving full-band coupling and shutoff of the two superconducting qubits. Even if the frequency of the superconducting qubit changes due to the transition of the superconducting qubit to a higher energy level, the coupling and shutoff between the two superconducting qubits can still be achieved, which is beneficial to suppressing high-energy level leakage and improving the fidelity of the parallel logic gates in the coupling device of the superconducting qubits. In addition, since the coupling and shutoff between the two superconducting qubits are independent of the frequency of the two superconducting qubits, it provides greater freedom for the frequency allocation of multiple superconducting qubits, and there is no coupling leakage problem when performing parallel gate operations in multiple bits, thus supporting high-fidelity multi-bit parallel gates. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG1 is a schematic diagram of a structure of a quantum computer;

[0037] FIG2 is a schematic diagram of a first structure of a coupling device for superconducting quantum bits in an embodiment of the present application;

[0038] FIG3 is a schematic diagram of several structures of the first superconducting quantum bit in an embodiment of the present application;

[0039] FIG4 is a schematic structural diagram of a first coupling module in an embodiment of the present application;

[0040] FIG5( a ) is a schematic diagram of a second structure of a coupling device for superconducting quantum bits in an embodiment of the present application;

[0041] FIG5( b ) is a schematic diagram of a third structure of a coupling device for superconducting quantum bits in an embodiment of the present application;

[0042] FIG6 is a schematic diagram of several structures of the second superconducting quantum bit in an embodiment of the present application;

[0043] FIG7 is a schematic diagram of a first embodiment of an adjustable coupling module in an embodiment of the present application;

[0044] FIG8 is a schematic diagram of several structures of an adjustable coupler and a fixed coupler in an embodiment of the present application;

[0045] FIG9 is a schematic diagram of a first structure of a second coupling module in an embodiment of the present application;

[0046] FIG10 is a schematic diagram of a second embodiment of the adjustable coupling module in the embodiment of the present application;

[0047] FIG11 is a schematic diagram of a second structure of a second coupling module in an embodiment of the present application;

[0048] FIG12 is a schematic diagram of a first structure of a superconducting quantum chip according to an embodiment of the present application;

[0049] FIG13 is a schematic diagram of a second structure of a superconducting quantum chip in an embodiment of the present application. DETAILED DESCRIPTION

[0050] The present invention provides a superconducting qubit coupling device, a superconducting quantum chip, and a quantum computer. These devices simplify the regulation of the coupling between two superconducting qubits, enabling full-band coupling between the two superconducting qubits and providing greater freedom in frequency allocation for multiple superconducting qubits. Furthermore, this design helps suppress high-energy-level leakage and improves the fidelity of parallel logic gates in the superconducting qubit coupling device.

[0051] It should be noted that the terms "first", "second", etc. (if any) in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] This application can be primarily applied to superconducting quantum computing scenarios, which is a quantum computing solution based on superconducting circuits. Superconducting circuits are microwave circuits composed of basic components such as capacitors, inductors, transmission lines, and Josephson junctions. Superconducting circuit chips operate in an ultra-low temperature environment provided by a dilution refrigerator to achieve superconductivity. Superconducting quantum circuits are highly compatible with existing integrated circuit technologies in terms of design, preparation, and measurement. They allow for highly flexible design and control of the energy levels and coupling of quantum bits, and have great potential for scalability. The following is an introduction to quantum computers in the context of superconducting quantum computing.

[0053] Figure 1 is a schematic diagram of the structure of a quantum computer. As shown in Figure 1, the quantum computer includes: a dilution refrigerator for providing a low-temperature environment, a superconducting quantum chip for implementing quantum computing information carriers, and a measurement and control system for manipulating the state of quantum bits to perform computational operations and read the quantum bit states. The superconducting quantum chip is placed in a low-temperature environment. The measurement and control system controls the microwave source and modulates the pulse signal according to the requirements of the computational operation, inputting a series of microwave pulse sequences into the superconducting quantum chip to manipulate the quantum state of the bits. After all operations are completed, the measurement and control system outputs a measurement pulse signal to the superconducting quantum chip. The return signal is used to obtain the state of the superconducting quantum bits and the computational results. Furthermore, as shown in Figure 1, the superconducting quantum chip includes a coupling device for multiple superconducting quantum bits arranged in a two-dimensional array. The coupling device for each superconducting quantum bit includes two superconducting quantum bits and a coupler located between the two superconducting quantum bits. The superconducting quantum bit refers to a superconducting resonant circuit including nonlinear components. It should be understood that the two-dimensional array arrangement shown in Figure 1 is only a specific example. In actual applications, superconducting quantum chips can also adopt other arrangements, such as triangular arrays and hexagonal lattice arrays, and the specific arrangements are not limited here. The coupling device of superconducting quantum bits is described in detail below.

[0054] It should be noted that in some existing solutions, two superconducting qubits are coupled through a traditional tunable coupler. The equivalent coupling strength between the two superconducting qubits is expressed as: Among them, g 12 represents the direct coupling strength between two superconducting qubits. When g 12 When is positive, the frequencies ω1 and ω2 of the two superconducting quantum bits will be tuned to be lower than the frequency ω of the tunable coupler. c , that is, ω1<ω c And ω2<ω c In this way, by adjusting ω c The two terms in the above equation can be made to cancel each other, thus achieving coupling-off between the two superconducting qubits. However, we found that this cancellation is dependent on the frequencies of the two superconducting qubits and the frequency of the tunable coupler. If the frequencies of the superconducting qubits change, or if the superconducting qubits leak to higher energy levels, the coupling-off condition will no longer hold. This property poses significant challenges to multi-qubit automatic calibration and parallel gates.

[0055] FIG2 is a schematic diagram of the first structure of the coupling device of the superconducting qubit in the embodiment of the present application. As shown in FIG2, the coupling device of the superconducting qubit includes a first superconducting qubit 10, a second superconducting qubit 20, an adjustable coupling module 30, a first coupling module 40, and a second coupling module 50. Among them, the adjustable coupling module 30 is coupled to the first superconducting qubit 10 through the first coupling module 40, and the adjustable coupling module 30 is coupled to the first superconducting qubit 20 through the second coupling module 50. The adjustable coupling module 30 includes a first resonant circuit and a second resonant circuit, and the frequency of at least one resonant circuit in the adjustable coupling module 30 is adjustable.

[0056] It should be noted that the coupling device of the superconducting quantum bit designed in the present application realizes that the coupling between the two superconducting quantum bits is turned off and is independent of the frequency of the two superconducting quantum bits. Specifically, the sign of the coupling strength between the first resonant circuit of the adjustable coupling module 30 and the first superconducting quantum bit 10 is opposite to the sign of the coupling strength between the second resonant circuit of the adjustable coupling module 30 and the first superconducting quantum bit 10, and the absolute value of the difference between the absolute value of the coupling strength between the first resonant circuit of the adjustable coupling module 30 and the first superconducting quantum bit 10 and the absolute value of the coupling strength between the second resonant circuit of the adjustable coupling module 30 and the first superconducting quantum bit 10 is less than the first preset value. At the same time, the sign of the coupling strength between the first resonant circuit of the adjustable coupling module 30 and the second superconducting quantum bit 20 is the same as the sign of the coupling strength between the second resonant circuit of the adjustable coupling module 30 and the second superconducting quantum bit 20, and the absolute value of the difference between the coupling strength between the first resonant circuit of the adjustable coupling module 30 and the first superconducting quantum bit 10 and the coupling strength between the second resonant circuit of the adjustable coupling module 30 and the first superconducting quantum bit 10 is less than the first preset value. For example, the first preset value may be 50 MHz.

[0057] In short, the coupling-off condition between the two superconducting qubits is that the coupling strengths between the two resonant circuits of the adjustable coupling module 30 and the first superconducting qubit 10 have opposite signs and are the same or similar in magnitude, and the coupling strengths between the two resonant circuits of the adjustable coupling module 30 and the second superconducting qubit 20 have the same sign and are the same or similar in magnitude. The equivalent coupling strength between the first superconducting qubit 10 and the second superconducting qubit 20 is expressed as:

[0058] Among them, Δ icj =ω i -ω cj represents the detuning between the i-th superconducting quantum bit and the j-th resonant circuit, g i is the absolute value of the coupling strength between the two resonant circuits and the i-th superconducting qubit, ω c1 represents the frequency of the first resonant circuit, ω c2 represents the frequency of the second resonant circuit. It can be seen that when ω c1 =ω c2 When g eff It is unconditionally equal to 0, that is, the coupling between the two superconducting quantum bits is independent of the frequencies of the two superconducting quantum bits, where the frequency of the superconducting quantum bit can be understood as the frequency difference between the two states (such as 0 and 1) of the super-large quantum bit storing information. It should be understood that in practical applications, ω can also be accepted. c1 With ω c2 Similar but not identical, that is, ω c1With ω c2 The absolute value of the difference between the two superconducting qubits is less than a second preset value, for example, the second preset value may be 500 MHz. Furthermore, the coupling between the two superconducting qubits being turned off may be understood as the coupling strength between the two superconducting qubits being less than a certain threshold.

[0059] It should be noted that the present application adjusts the frequency of the first resonant circuit to be the same as or close to the frequency of the second resonant circuit, which is equivalent to only requiring a single calibration. In the subsequent process, no matter how the frequency of the superconducting quantum bit changes, there is no need to change the bias point of the adjustable coupling module, thereby achieving full-band coupling and shutoff of the two superconducting quantum bits. In other words, even if the frequency of the superconducting quantum bit changes due to the transition to a high energy level of the superconducting quantum bit, the coupling between the two superconducting quantum bits can still be shut off, which is beneficial to suppressing high-energy level leakage and improving the fidelity of the parallel logic gate in the coupling device of the superconducting quantum bit. In addition, since the coupling and shutoff between the two superconducting quantum bits are independent of the frequency of the two superconducting quantum bits, it provides greater freedom for the frequency allocation of multiple superconducting quantum bits, and there is no coupling leakage problem when performing parallel gate operations in multiple bits, thereby supporting high-fidelity multi-bit parallel gates.

[0060] It should be understood that the design of this application enables the impedance of the first resonant circuit to be the same as or close to the impedance of the second resonant circuit when the frequency of the first resonant circuit is the same as or close to the frequency of the second resonant circuit, thereby achieving the above-mentioned coupling shutdown condition. Accordingly, it is necessary to specifically design each component of the superconducting qubit coupling device, which is described in detail below.

[0061] As shown in FIG2 , first superconducting qubit 10 includes electrode 101, electrode 102, and inductor circuit 103, wherein electrode 101 is connected to electrode 102 via inductor circuit 103. Electrode 101 and electrode 102 are not grounded, and first superconducting qubit 10 can also be referred to as a dual-electrode floating superconducting qubit. Inductor circuit 103 can be an inductive circuit composed of multiple linear inductors and multiple Josephson junctions connected in series, in parallel, or in a combination of series and parallel.

[0062] It should be understood that in order to achieve the above-mentioned coupling-off condition in which the coupling strengths between the two resonant circuits of the adjustable coupling module 30 and the first superconducting qubit 10 have opposite signs and are the same or similar in magnitude, the first resonant circuit is coupled to the electrode 101 via the first coupling module 40, and the second resonant circuit is coupled to the electrode 102 via the first coupling module 40. Moreover, when the first superconducting qubit 10 is in the resonant state, the voltage on the electrode 101 and the voltage on the electrode 102 have opposite signs. The resonant state of the first superconducting qubit 10 can also be referred to as the first superconducting qubit 10 being in an excited state. At the same time, the absolute value of the difference between the capacitance to ground of the first electrode 101 and the capacitance to ground of the second electrode 102 is less than a third preset value. For example, the third preset value may be 50 fF.

[0063] FIG3 is a schematic diagram of several structures of the first superconducting quantum bit in the embodiment of the present application. As shown in FIG3 , the types of the first superconducting quantum bit 10 include fixed-frequency Transmon, adjustable Transmon, flux bit with capacitor shunt, Fluxonium bit with linear inductance, and Fluxonium bit with large junction series. Among them, the dephasing time of the fixed-frequency Transmon is longer, but the frequency is not adjustable. The frequency of the adjustable Transmon is adjustable, but the dephasing time is relatively short. The anharmonicity of the flux quantum bit with capacitor shunt can be adjusted to positive. The frequencies of the two types of Fluxonium bits are lower, but the anharmonicity is generally large, and the coherence time is longer. It can be seen that no matter which type of first superconducting quantum bit, it includes two ungrounded electrodes, and the difference in the inductance circuit determines the type of the first superconducting quantum bit 10. Generally speaking, the sizes of all capacitors in FIG3 are within the range of 1fF to 50pF, and the sizes of all inductors (including Josephson junctions and linear inductors) are within the range of 0.1nH to 200nH.

[0064] Figure 4 is a structural diagram of the first coupling module in an embodiment of the present application. As shown in Figure 4, the first coupling module includes a capacitor 401 and a capacitor 402. The first resonant circuit of the adjustable coupling module 30 is coupled to the electrode 101 of the first superconducting quantum bit 10 through the capacitor 401, and the second resonant circuit of the adjustable coupling module 30 is coupled to the electrode 102 of the first superconducting quantum bit 10 through the capacitor 402. Among them, the difference between the capacitor 401 and the capacitor 402 is less than the third preset value. On this basis, the parasitic capacitor 403 in the first coupling module is located between the first resonant circuit and the electrode 102, and the parasitic capacitor 404 in the first coupling module is located between the second resonant circuit and the electrode 101, and the absolute value of the difference between the parasitic capacitor 403 and the parasitic capacitor 404 is less than the third preset value.

[0065] FIG5( a ) is a schematic diagram of a second structure of a coupling device for a superconducting qubit in an embodiment of the present application. FIG5( b ) is a schematic diagram of a third structure of a coupling device for a superconducting qubit in an embodiment of the present application. For the second superconducting qubit 20 , as an example, the second superconducting qubit 20 may be a single-electrode grounded structure as shown in FIG5( a ), i.e., the second superconducting qubit 20 includes an electrode 201 and an inductor circuit 202 , and the first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are respectively coupled to the electrode 201 via the second coupling module 40 . As another example, the second superconducting quantum bit 20 can be a dual-electrode floating structure as shown in Figure 5(b), that is, the second superconducting quantum bit 20 includes an electrode 203, an electrode 204 and an inductor circuit 205, and the electrode 203 and the electrode 204 are connected through the inductor circuit 205. In order to achieve the above-mentioned coupling shutdown condition, the coupling strength between the two resonant circuits of the adjustable coupling module 30 and the second superconducting quantum bit 20 has the same sign and the same or similar size, the first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are respectively coupled to one of the electrodes of the second superconducting quantum bit 20, such as electrode 203, through the second coupling module 40.

[0066] FIG6 is a schematic diagram of several structures of the second superconducting quantum bit in the embodiment of the present application. As shown in FIG6, regardless of whether the second superconducting quantum bit 20 adopts a single-electrode grounded structure or a dual-electrode floating structure, the types of the second superconducting quantum bit 20 include fixed-frequency Transmon, adjustable Transmon, flux bit with capacitor shunt, Fluxonium bit with linear inductance, and Fluxonium bit with large junction series. Among them, the dephasing time of the fixed-frequency Transmon is longer, but the frequency is not adjustable. The frequency of the adjustable Transmon is adjustable, but the dephasing time is relatively short. The anharmonicity of the flux quantum bit with capacitor shunt can be adjusted to positive. The frequencies of the two types of Fluxonium bits are lower, but the anharmonicity is generally large and the coherence time is longer. It can be seen that the difference in the inductance circuit determines the type of the second superconducting quantum bit 20. Generally speaking, the sizes of all capacitors in FIG5 are within the range of 1fF to 50pF, and the sizes of all inductors (including Josephson junctions and linear inductors) are within the range of 0.1nH to 200nH.

[0067] It should be noted that the adjustable coupling module 30 is a circuit composed of capacitors, inductors, transmission lines, or a combination thereof, and the adjustable coupling module 30 also includes adjustable inductors and / or adjustable capacitors. Several possible implementations of the adjustable coupling module 30 are described below.

[0068] In a possible implementation, the adjustable coupling module 30 includes two independent single-mode circuits. Each independent single-mode circuit has multiple options. For example, the independent single-mode circuit is a fixed coupler or an adjustable coupler.

[0069] FIG7 is a schematic diagram of a first embodiment of an adjustable coupling module in an embodiment of the present application. As shown in (a) of FIG7 , as an example, the first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are both adjustable couplers, that is, the frequencies of the first resonant circuit and the second resonant circuit are both adjustable. As shown in (b) of FIG7 , as another example, the first resonant circuit of the adjustable coupling module 30 is an adjustable coupler, and the second resonant circuit of the adjustable coupling module 30 is a fixed coupler, that is, the frequency of the first resonant circuit is adjustable, and the frequency of the second resonant circuit is fixed. It should be understood that for an adjustable coupler, the adjustable coupler includes an adjustable inductor and / or an adjustable capacitor, and the adjustable coupler also includes a bias circuit, which is used to adjust the size of the adjustable inductor and / or the adjustable capacitor.

[0070] FIG8 is a schematic diagram of several structures of adjustable couplers and fixed couplers in an embodiment of the present application. As shown in FIG8 , whether it is an adjustable coupler or a fixed coupler, its specific types include grounded couplers, floating same-end couplers, floating heterodyne couplers and transmission line couplers. Generally speaking, the sizes of all capacitors in FIG8 are within the range of 1fF to 50pF, the sizes of all inductors (including Josephson junctions and linear inductors) are within the range of 0.1nH to 200nH, the characteristic impedances of all transmission lines are within the range of 1Ω to 1000Ω, and the lengths of transmission lines are within the range of 100μm to 100mm. It should be understood that selecting two types of floating type or transmission line type couplers in FIG8 can make the specific size of the coupler longer, which helps to widen the distance between the two superconducting quantum bits, thereby increasing the wiring space and thus improving the scalability. At the same time, longer couplers can also be used for long-distance coupling across chips.

[0071] Figure 9 is a schematic diagram of the first structure of the second coupling module in an embodiment of the present application. It should be understood that if the adjustable coupling module 30 adopts the embodiment shown in Figure 7 above, the second coupling module 50 adopts the structure shown in Figure 9. Specifically, the second coupling module 50 includes a capacitor 501 and a capacitor 502. The first resonant circuit of the adjustable coupling module 30 is coupled to one of the electrodes of the second superconducting quantum bit 20 through the capacitor 501, and the second resonant circuit of the adjustable coupling module 30 is coupled to one of the electrodes of the second superconducting quantum bit 20 through the capacitor 502. Among them, the absolute value of the difference between the capacitor 501 and the capacitor 502 is less than the third preset value, so as to achieve the above-mentioned coupling off condition. The coupling strength between the two resonant circuits of the adjustable coupling module 30 and the second superconducting quantum bit 20 has the same sign and the same or similar size.

[0072] As an example, if the second superconducting qubit 20 adopts the single-electrode grounding structure shown in Figure 5(a), the second coupling module 50 adopts the structure shown in Figure 9(a). The first resonant circuit of the adjustable coupling module 30 is coupled to the electrode 201 of the second superconducting qubit 20 through the capacitor 501, and the second resonant circuit of the adjustable coupling module 30 is coupled to the electrode 201 of the second superconducting qubit 20 through the capacitor 502.

[0073] As another example, if the second superconducting qubit 20 adopts a dual-electrode floating structure as shown in FIG5(b), the second coupling module 50 adopts a structure as shown in FIG9(b). The first resonant circuit of the adjustable coupling module 30 is coupled to the electrode 203 of the second superconducting qubit 20 through a capacitor 501, and the second resonant circuit of the adjustable coupling module 30 is coupled to the electrode 203 of the second superconducting qubit 20 through a capacitor 502. In this example, the second coupling module 50 also includes a parasitic capacitor 503 located between the first resonant circuit and the electrode 204 and a parasitic capacitor 504 located between the second resonant circuit and the electrode 204. The absolute value of the difference between the two parasitic capacitors is less than a third preset value, so as to achieve the above-mentioned coupling-off condition in which the coupling strength between the two resonant circuits of the adjustable coupling module 30 and the second superconducting qubit 20 has the same sign and the same or similar magnitude.

[0074] In another possible implementation, the first resonant circuit and the second resonant circuit of the adjustable coupling module 30 have a shared circuit structure, and this shared circuit structure is coupled to the second superconducting qubit 20 via the second coupling module 50 .

[0075] Figure 10 is a schematic diagram of a second embodiment of the adjustable coupling module in the embodiment of the present application. As shown in Figure 10, several specific designs of adjustable coupling modules 30 are provided. For example, the adjustable coupling module 30 is a single adjustable TCQ (Tunable coupling qubit) coupler shown in Figure 10 (a), a dual adjustable TCQ coupler shown in Figure 10 (b), a single adjustable shared transmission line coupler shown in Figure 10 (c), or a dual adjustable shared transmission line coupler shown in Figure 10 (d). It can be seen that each circuit structure shown in Figure 10 includes 3 nodes, 2 of which are located on the same side and the other 1 node is located on the other side. The 2 nodes on the same side are coupled to the first superconducting quantum bit 10 through a first coupling module 40, and the 1 node on the other side is coupled to the second superconducting quantum bit 20 through a second coupling module 50. It should be understood that the partial circuit connected to the 1 node on the other side is the circuit structure shared by the first resonant circuit and the second resonant circuit in the adjustable coupling module 30. It should be noted that for the single-tunable couplers shown in (a) and (c) of FIG10 , the frequency of only one resonant circuit is adjustable. For the dual-tunable couplers shown in (b) and (d) of FIG10 , the frequencies of both resonant circuits are adjustable.

[0076] Generally speaking, all capacitors in Figure 10 are within the range of 1fF to 50pF, all inductors (including Josephson junctions and linear inductors) are within the range of 0.1nH to 200nH, the characteristic impedance of all transmission lines is within the range of 1Ω to 1000Ω, and the transmission line length is within the range of 100μm to 100mm. It should be understood that selecting a floating type coupler as shown in Figures 10 (a) and (b) or a transmission line type coupler as shown in Figures 10 (c) and (d) can make the specific dimensions of the coupler longer, which helps to increase the distance between the two superconducting qubits, thereby increasing the wiring space and improving scalability.

[0077] FIG11 is a schematic diagram of the second structure of the second coupling module in an embodiment of the present application. It should be understood that if the adjustable coupling module 30 adopts the embodiment shown in FIG10 above, the second coupling module 50 adopts the structure shown in FIG11. Specifically, the second coupling module 50 includes a capacitor 505. The first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are both coupled to one of the electrodes of the second superconducting quantum bit 20 through the capacitor 505. That is to say, since the first resonant circuit and the second resonant circuit of the adjustable coupling module 30 have a common circuit structure, this part of the common circuit structure is coupled to one of the electrodes of the second superconducting quantum bit 20 through a single capacitor to achieve the above-mentioned coupling off condition. The coupling strength between the two resonant circuits of the adjustable coupling module 30 and the second superconducting quantum bit 20 has the same sign and the same or similar magnitude. Compared with the method shown in FIG9, the method shown in FIG11 is easier to achieve the coupling off condition.

[0078] As an example, if the second superconducting qubit 20 adopts the single-electrode grounding structure shown in FIG5(a), and the second coupling module 50 adopts the structure shown in FIG11(a), the first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are both coupled to the electrode 201 of the second superconducting qubit 20 via the capacitor 505.

[0079] As another example, if the second superconducting qubit 20 adopts a dual-electrode floating structure as shown in FIG5(b), the second coupling module 50 adopts a structure as shown in FIG11(b). The first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are both coupled to the electrode 203 of the second superconducting qubit 20 through the capacitor 505. In this example, the second coupling module 50 further includes a parasitic capacitor 506 located between the circuit structure shared by the first resonant circuit and the second resonant circuit and the electrode 204. The parasitic capacitor 506 is smaller than the capacitor 503, so as to achieve the above-mentioned coupling-off condition. The coupling strength between the two resonant circuits of the adjustable coupling module 30 and the second superconducting qubit 20 has the same sign and the same or similar magnitude.

[0080] It should be noted that, based on the superconducting qubit coupling devices described above, multiple superconducting qubit coupling devices are arranged in a two-dimensional array to form a superconducting quantum chip. The following describes possible distribution methods for superconducting qubit coupling devices in a superconducting quantum chip. It should be understood that, since square lattice arrays are the most widely used, the following primarily describes implementations for square lattice array arrangements.

[0081] Figure 12 is a schematic diagram of the first structure of the superconducting quantum chip in an embodiment of the present application. As shown in Figure 12, the coupling device of each superconducting quantum bit in the superconducting quantum chip adopts the structure shown in Figure 5(b), that is, the first superconducting quantum bit and the second superconducting quantum bit both adopt a dual-electrode floating ground design. It can be seen that the coupling device of each two adjacent superconducting quantum bits shares one superconducting quantum bit. As an example, as shown in Example 1 in Figure 12, the coupling device of two adjacent superconducting quantum bits shares the first superconducting quantum bit. As another example, as shown in Example 2 in Figure 12, the coupling device of two adjacent superconducting quantum bits shares the second superconducting quantum bit. As yet another example, as shown in Example 3 in Figure 12, the superconducting quantum bit shared by the coupling device of two adjacent superconducting quantum bits is the first superconducting quantum bit in the coupling device of one of the superconducting quantum bits, and is the second superconducting quantum bit in the coupling device of the other superconducting quantum bit. In other words, if the adjustable coupling module 30, the first coupling module 40, and the second coupling module 50 in the coupling device of each superconducting qubit are collectively referred to as a coupler, then every two adjacent superconducting qubits in the superconducting quantum chip are coupled via the coupler. Moreover, for any superconducting qubit, the superconducting qubit can serve as either the first superconducting qubit or the second superconducting qubit. Therefore, for this embodiment, only one type of superconducting qubit needs to be designed, and this type of superconducting qubit can be placed in different positions to play the role of the first superconducting qubit or the second superconducting qubit, resulting in a better overall symmetry of the superconducting quantum chip.

[0082] Figure 13 is a schematic diagram of the second structure of the superconducting quantum chip in an embodiment of the present application. As shown in Figure 13, the first superconducting quantum bit adopts a dual-electrode floating ground design. It should be noted that the first electrode 101 of the first superconducting quantum bit includes two interconnected and cross-placed sub-electrodes 1, and the second electrode 102 of the first superconducting quantum bit includes two interconnected and cross-placed sub-electrodes 2. The common intersection of the two sub-electrodes 1 and the two sub-electrodes 2 is the connection point of the inductor circuit 103. It can be seen that the coupling device of each two adjacent superconducting quantum bits shares one superconducting quantum bit. As an example, as shown in Example 1 in Figure 13, the coupling device of two adjacent superconducting quantum bits shares the first superconducting quantum bit. As another example, as shown in Example 2 in Figure 13, the coupling device of two adjacent superconducting quantum bits shares the second superconducting quantum bit. It should be understood that this embodiment does not limit the design method adopted by the second superconducting quantum bit. For example, the second superconducting quantum bit can choose a grounded or floating design. For this embodiment, the two electrodes of the first superconducting quantum bit are designed to be four cross-distributed sub-electrodes, ensuring that the coupling device of each superconducting quantum bit sharing the first superconducting quantum bit can utilize one set of sub-electrode 1 and sub-electrode 2, and the overall symmetry of the superconducting quantum chip is good.

[0083] It should be noted that the above embodiments are intended only to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A coupling device for superconducting quantum bits, characterized in that: include: A first superconducting qubit, a second superconducting qubit, a first coupling module, a second coupling module and an adjustable coupling module, wherein the adjustable coupling module is coupled to the first superconducting qubit through the first coupling module, the adjustable coupling module is coupled to the second superconducting qubit through the second coupling module, the adjustable coupling module includes a first resonant circuit and a second resonant circuit, and the frequency of at least one of the first resonant circuit and the second resonant circuit is adjustable; The sign of the coupling strength between the first resonant circuit and the first superconducting qubit is opposite to the sign of the coupling strength between the second resonant circuit and the first superconducting qubit, and the absolute value of the difference between the absolute value of the coupling strength between the first resonant circuit and the first superconducting qubit and the absolute value of the coupling strength between the second resonant circuit and the first superconducting qubit is less than a first preset value; The sign of the coupling strength between the first resonant circuit and the second superconducting qubit is the same as the sign of the coupling strength between the second resonant circuit and the second superconducting qubit, and the absolute value of the difference between the coupling strength between the first resonant circuit and the second superconducting qubit and the coupling strength between the second resonant circuit and the second superconducting qubit is less than the first preset value; When the absolute value of the difference between the frequency of the first resonance circuit and the frequency of the second resonance circuit is less than a second preset value, the coupling between the first superconducting qubit and the second superconducting qubit is turned off.

2. The superconducting quantum bit coupling device according to claim 1, characterized in that: The first superconducting qubit includes a first electrode and a second electrode, the first electrode and the second electrode are not grounded, and when the first superconducting qubit is in resonance, a voltage on the first electrode and a voltage on the second electrode have opposite signs.

3. The superconducting quantum bit coupling device according to claim 2, characterized in that: The first electrode includes a first capacitance to ground, the second electrode includes a second capacitance to ground, and an absolute value of a difference between the first capacitance to ground and the second capacitance to ground is smaller than a third preset value.

4. The superconducting quantum bit coupling device according to claim 2 or 3, characterized in that: The first electrode is connected to the second electrode via a first inductor circuit, and the first inductor circuit includes at least one Josephson junction.

5. The superconducting quantum bit coupling device according to any one of claims 2 to 4, characterized in that: The first coupling module includes a first capacitor and a second capacitor, the first resonant circuit is coupled to the first electrode through the first capacitor, the second resonant circuit is coupled to the second electrode through the second capacitor, and the absolute value of the difference between the first capacitor and the second capacitor is less than the third preset value.

6. The superconducting quantum bit coupling device according to any one of claims 2 to 5, characterized in that: The first parasitic capacitor in the first coupling module is located between the first resonant circuit and the second electrode, the second parasitic capacitor in the first coupling module is located between the second resonant circuit and the first electrode, and the absolute value of the difference between the first parasitic capacitor and the second parasitic capacitor is less than the third preset value.

7. The superconducting quantum bit coupling device according to any one of claims 2 to 6, characterized in that: The first resonant circuit and the second resonant circuit are both adjustable couplers; or, The first resonant circuit is an adjustable coupler, and the second resonant circuit is a fixed coupler.

8. The superconducting quantum bit coupling device according to claim 7, characterized in that: The second superconducting quantum bit includes a third electrode, the third electrode is grounded through a second inductance circuit, the second inductance circuit includes at least one Josephson junction, and the first resonant circuit and the second resonant circuit are respectively coupled to the third electrode through the second coupling module.

9. The superconducting quantum bit coupling device according to claim 8, characterized in that: The second coupling module includes a third capacitor and a fourth capacitor, the first resonant circuit is coupled to the third electrode of the second superconducting quantum bit through the third capacitor, the second resonant circuit is coupled to the third electrode of the second superconducting quantum bit through the fourth capacitor, and the absolute value of the difference between the third capacitor and the fourth capacitor is less than the third preset value.

10. The superconducting quantum bit coupling device according to claim 7, characterized in that: The second superconducting quantum bit includes a fourth electrode and a fifth electrode, the fourth electrode and the fifth electrode are not grounded, the fourth electrode is connected to the fifth electrode through a third inductance circuit, the third inductance circuit includes at least one Josephson junction, and the first resonant circuit and the second resonant circuit are respectively coupled to the fourth electrode through the second coupling module.

11. The superconducting quantum bit coupling device according to claim 10, characterized in that: The second coupling module includes a third capacitor and a fourth capacitor, the first resonant circuit is coupled to the fourth electrode of the second superconducting quantum bit through the third capacitor, the second resonant circuit is coupled to the fourth electrode of the second superconducting quantum bit through the fourth capacitor, and the absolute value of the difference between the third capacitor and the fourth capacitor is less than the third preset value.

12. The superconducting quantum bit coupling device according to claim 10 or 11, characterized in that: The third parasitic capacitor in the second coupling module is located between the first resonant circuit and the fifth electrode, the fourth parasitic capacitor in the second coupling module is located between the second resonant circuit and the fifth electrode, and the absolute value of the difference between the third parasitic capacitor and the fourth parasitic capacitor is less than the third preset value.

13. The superconducting quantum bit coupling device according to any one of claims 2 to 6, characterized in that: The first resonant circuit and the second resonant circuit have a common circuit structure.

14. The superconducting quantum bit coupling device according to claim 13, characterized in that: The second superconducting quantum bit includes a third electrode, the third electrode is grounded through a second inductance circuit, the second inductance circuit includes at least one Josephson junction, and the circuit structure shared by the first resonant circuit and the second resonant circuit is coupled to the third electrode through the second coupling module.

15. The superconducting quantum bit coupling device according to claim 14, characterized in that: The second coupling module includes a fifth capacitor, and the circuit structure shared by the first resonant circuit and the second resonant circuit is coupled to the third electrode of the second superconducting quantum bit through the fifth capacitor.

16. The superconducting quantum bit coupling device according to claim 13, characterized in that: The second superconducting quantum bit includes a fourth electrode and a fifth electrode, both of which are not grounded, and the fourth electrode is connected to the fifth electrode through a third inductance circuit, and the third inductance circuit includes at least one Josephson junction, and the circuit structure shared by the first resonant circuit and the second resonant circuit is coupled to the fourth electrode through the second coupling module.

17. The superconducting quantum bit coupling device according to claim 16, characterized in that: The second coupling module includes a fifth capacitor, and the circuit structure shared by the first resonant circuit and the second resonant circuit is coupled to the fourth electrode of the second superconducting quantum bit through the fifth capacitor.

18. The superconducting quantum bit coupling device according to claim 16 or 17, characterized in that: The fifth parasitic capacitor in the second coupling module is located between the circuit structure shared by the first resonant circuit and the second resonant circuit and the fifth electrode, and the fifth parasitic capacitor is smaller than the fifth capacitor.

19. The superconducting quantum bit coupling device according to any one of claims 1 to 18, characterized in that: At least one of the first resonant circuit and the second resonant circuit includes an adjustable inductor and / or an adjustable capacitor, and at least one of the first resonant circuit and the second resonant circuit also includes a bias circuit, and the bias circuit is used to adjust the size of the adjustable inductor and / or the size of the adjustable capacitor.

20. The superconducting quantum bit coupling device according to any one of claims 1 to 19, characterized in that: The first superconducting qubit is a fixed-frequency Transmon, an adjustable Transmon, a Fluxonium, or a flux qubit with capacitor shunt, and the second superconducting qubit is a fixed-frequency Transmon, an adjustable Transmon, a Fluxonium, or a flux qubit with capacitor shunt.

21. A superconducting quantum chip, characterized in that: A method for preparing a superconducting qubit coupling device comprising a plurality of superconducting qubit coupling devices according to any one of claims 1 to 20, wherein the plurality of superconducting qubit coupling devices are distributed in an array, the coupling devices of every two adjacent superconducting qubits share one superconducting qubit, and the first superconducting qubit and the second superconducting qubit in each superconducting qubit coupling device include two ungrounded electrodes; The shared superconducting qubit is the first superconducting qubit or the second superconducting qubit in the coupling device of two adjacent superconducting qubits; or, The shared superconducting qubit is a first superconducting qubit in a coupling device of one of the superconducting qubits, and the shared superconducting qubit is a second superconducting qubit in a coupling device of another of the superconducting qubits.

22. A superconducting quantum chip, characterized in that: A method comprising: comprising a plurality of coupling devices for superconducting qubits according to any one of claims 1 to 20, wherein the plurality of coupling devices for superconducting qubits are distributed in an array, wherein the coupling devices for every two adjacent superconducting qubits share one superconducting qubit, wherein the first superconducting qubit in the coupling device for each superconducting qubit comprises a first electrode and a second electrode, wherein the first electrode and the second electrode are not grounded, wherein the first electrode comprises two interconnected sub-electrodes, wherein the second electrode comprises two interconnected sub-electrodes, wherein the two sub-electrodes of the first electrode and the two sub-electrodes of the second electrode are placed crosswise, and wherein the shared superconducting qubit is the first superconducting qubit or the second superconducting qubit in the coupling device for two adjacent superconducting qubits.

23. A quantum computer, characterized in that: include: A dilution refrigerator, a measurement and control system, and a superconducting quantum chip as claimed in claim 21 or 22.

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