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

Abstract

The embodiment of the invention discloses a coupling device of superconducting quantum bits, a superconducting quantum chip and a quantum computer. The superconducting quantum bit coupling device comprises a first superconducting quantum bit, a second superconducting quantum bit, a first coupling module, a second coupling module and an adjustable coupling module, the adjustable coupling module comprises two resonance circuits, and the frequency of at least one resonance circuit is adjustable. According to the invention, the coupling strength symbols between the two resonance circuits of the adjustable coupling module and the first superconducting quantum bit are opposite and the coupling strength symbols are the same or similar, and the coupling strength symbols between the two resonance circuits of the adjustable coupling module and the second superconducting quantum bit are the same and the coupling strength symbols are the same or similar. Therefore, when the frequency of the first resonance circuit is the same as or close to the frequency of the second resonance circuit, the coupling between the two superconducting quantum bits is turned off, the coupling turn-off is irrelevant to the frequency of the two superconducting quantum bits, and the two superconducting quantum bits have the characteristic of full-band coupling turn-off.

Description

Technical Field

[0001] 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

[0002] Quantum computing is a new type of computing method based on quantum mechanics that uses the properties of quantum superposition and entanglement. In some specific problems, such as large number decomposition and quantum chemical simulation, quantum computing has the advantage of exponential acceleration compared to classical computing in theory. Superconducting quantum bits 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 work in an ultra-low temperature environment provided by a dilution refrigerator to achieve superconductivity.

[0003] At the beginning of the development of superconducting quantum bits, fixed capacitive coupling or quantum bus coupling was used between superconducting quantum bits. This type of design reduces circuit complexity, reduces the burden of superconducting circuit design and micro-nano processing, and has achieved good results. However, with the expansion of the number of superconducting quantum bits, the scale of circuits is getting larger and larger. The crosstalk between bits caused by the fixed coupling between superconducting quantum bits that cannot be turned off has caused a series of difficult-to-solve problems such as difficulty in simultaneously executing single-bit logic gates and limited fidelity of two-bit logic gate operations.

[0004] In order 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 at the same time it has also increased the difficulty of manipulation because of the introduction of additional degrees of freedom of manipulation. The turn-off conditions of existing adjustable couplers are related to the frequency of superconducting qubits, and any frequency adjustment of superconducting qubits will require readjustment of the bias points of surrounding couplers. In other words, if the frequency of the superconducting qubit 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 qubit. Summary of the invention

[0005] 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 realizing the coupling and disconnection between two superconducting quantum bits, realize the full-band coupling and disconnection of two superconducting quantum bits, and provide greater freedom for the frequency allocation of multiple superconducting quantum bits.

[0006] In the first aspect, an embodiment of the present application provides a coupling device for a superconducting quantum bit, specifically comprising: a first superconducting quantum bit, a second superconducting quantum bit, a first coupling module, a second coupling module and an adjustable coupling module. Among them, the adjustable coupling module is coupled to the first superconducting quantum bit through the first coupling module, and the adjustable coupling module is coupled to the second superconducting quantum bit 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 coupling strengths between the first resonant circuit and the second resonant circuit and the first superconducting quantum bit are opposite in sign and the absolute value of the coupling strength is the same or similar, and the coupling strengths between the first resonant circuit and the second resonant circuit and the second superconducting quantum bit are opposite in sign and the coupling strengths are the same or similar. By adjusting the frequency of at least one resonant circuit in 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 quantum bit and the second superconducting quantum bit is turned off.

[0007] In this embodiment, only one adjustment is required 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. 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, and the full-band coupling shutdown of the two superconducting qubits is realized. Even if the frequency of the superconducting qubit changes due to the transition of the superconducting qubit to a high energy level, the coupling shutdown between the two superconducting qubits can still be realized, which is conducive 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 shutdown between the two superconducting qubits is 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.

[0008] In some possible embodiments, the first superconducting quantum bit includes a first electrode and a second electrode, both of which are not grounded, and 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 is of opposite signs and the same or similar magnitude.

[0009] In some possible embodiments, the first electrode includes a first capacitor to ground and a second capacitor to ground, and the first capacitor to ground and the second capacitor to ground are of the same or similar size, 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 size.

[0010] In some possible implementations, 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, which has good practicality.

[0011] 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 are of the same or similar size, 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 of the same or similar size.

[0012] In some possible implementations, the first parasitic capacitor in the first coupling module is located between the first resonant circuit and the second electrode, and the second parasitic capacitor in the first coupling module is located between the second resonant circuit and the first electrode. The first parasitic capacitor and the second parasitic capacitor are of the same or similar magnitude, which is conducive to achieving the above-mentioned coupling-off condition that 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.

[0013] In some possible implementations, the first resonant circuit and the second resonant circuit are both 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, which enhances the scalability of the solution.

[0014] In some possible implementations, the second superconducting qubit includes a third electrode, the third electrode is grounded through 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 through a second coupling module. In other words, the second superconducting qubit can adopt a single-electrode grounding structure, which has good feasibility.

[0015] In some possible implementations, 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, the second resonant circuit is coupled to the third electrode of the second superconducting qubit via the fourth capacitor, and the third capacitor and the fourth capacitor are of the same or similar size. In view of the scenario where the second superconducting qubit adopts a single-electrode grounding structure, a design method for the second coupling module is provided, which is conducive to achieving the same sign and the same or similar size of the coupling strength between the two resonant circuits of the adjustable coupling module and the second superconducting qubit in the above-mentioned coupling off condition.

[0016] In some possible implementations, 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 and the fifth electrode are connected through a third inductor circuit, the third inductor 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 a second coupling module. In other words, the second superconducting quantum bit can also adopt a dual-electrode floating structure, which improves the flexibility of this solution.

[0017] In some possible implementations, 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, the second resonant circuit is coupled to the fourth electrode of the second superconducting qubit via the fourth capacitor, and the third capacitor and the fourth capacitor are of the same or similar size. In view of the scenario where the second superconducting qubit adopts a dual-electrode floating structure, a design method for the second coupling module is provided, which is conducive to achieving the same sign and the same or similar size of the coupling strength between the two resonant circuits of the adjustable coupling module and the second superconducting qubit in the above-mentioned coupling off condition.

[0018] In some possible implementations, the third parasitic capacitor in the second coupling module is located between the first resonant circuit and the fifth electrode, and the fourth parasitic capacitor in the second coupling module is located between the second resonant circuit and the fifth electrode. The third parasitic capacitor and the fourth parasitic capacitor have the same or similar magnitudes, which is conducive to achieving the same sign and the same or similar magnitudes of the coupling strength between the two resonant circuits of the adjustable coupling module and the second superconducting quantum bit in the above-mentioned coupling off condition.

[0019] In some possible implementations, the first resonant circuit and the second resonant circuit have a common circuit structure, and this common 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.

[0020] In some possible implementations, the second superconducting quantum bit includes a third electrode, the third electrode is grounded through 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 through a second coupling module. In other words, the second superconducting quantum bit can adopt a single-electrode grounding structure, which has good feasibility.

[0021] 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. Another design method of the second coupling module is provided here, which has a simpler structure and is easier to achieve the coupling off condition.

[0022] In some possible implementations, the second superconducting quantum bit includes a fourth electrode and a fifth electrode, both of which are not grounded, the fourth electrode and the fifth electrode are connected via a third inductor circuit, the third 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 fourth electrode via a second coupling module. In other words, the second superconducting quantum bit can also adopt a dual-electrode floating structure, which improves the flexibility of this solution.

[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 fourth electrode of the second superconducting qubit via the fifth capacitor. Another design method of the second coupling module is provided here, which has a simpler structure and is easier to achieve the coupling off condition.

[0024] 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.

[0025] 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 also includes a bias circuit. The bias circuit is used to adjust the size of the adjustable inductor and / or the size of the adjustable capacitor, ensuring that the frequency of at least one resonant circuit in the adjustable coupling module is adjustable.

[0026] In some possible implementations, the first superconducting qubit is a fixed-frequency Transmon, an adjustable Transmon, Fluxonium, or a flux qubit with capacitor shunt, and the second superconducting qubit is a fixed-frequency Transmon, an adjustable Transmon, Fluxonium, or a flux qubit with capacitor shunt, which expands the applicable scenarios of this solution.

[0027] In a second 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, and the first superconducting quantum bit and the second superconducting quantum bit in the coupling device of each superconducting quantum bit include two ungrounded electrodes. In the superconducting quantum chip, 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. Alternatively, the shared superconducting quantum bit is the first superconducting quantum bit in the coupling device of one of the superconducting quantum bits, and the shared superconducting quantum bit is the second superconducting quantum bit in the coupling device of another superconducting quantum bit.

[0028] 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, every two adjacent superconducting qubits in the superconducting quantum chip are coupled through a coupler. Moreover, for any superconducting qubit, the superconducting qubit can be used 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 is 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.

[0029] 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, 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.

[0030] 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 that shares the first superconducting quantum bit can utilize one group of sub-electrodes 1 and sub-electrode 2, and the overall symmetry of the superconducting quantum chip is good.

[0031] 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.

[0032] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0033] The coupling device of the superconducting quantum bit provided in the present application includes a first superconducting quantum bit, a second superconducting quantum bit, a first coupling module, a second coupling module and an adjustable coupling module, and the adjustable coupling module includes a first resonant circuit and a second resonant circuit, and the frequency of at least one resonant circuit in 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 quantum bit 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 quantum bit 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 or close to the frequency of the second resonant circuit, the coupling between the first superconducting quantum bit and the second superconducting quantum bit is turned off. It can be seen that the present application only requires one adjustment to realize the coupling shutoff between the first superconducting quantum bit and the second superconducting quantum bit, and the coupling shutoff is independent of the frequency of the two superconducting quantum bits, which simplifies the adjustment method for realizing the coupling shutoff between the two superconducting quantum bits. 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, so that the full-band coupling and shutdown of the two superconducting qubits can be achieved. Even if the frequency of the superconducting qubit changes due to the transition of the superconducting qubit to a high energy level, the coupling and shutdown between the two superconducting qubits can still be achieved, which is beneficial to suppress high-energy level leakage and improve the fidelity of the parallel logic gates in the coupling device of the superconducting qubit. In addition, since the coupling and shutdown 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

[0034] Figure 1 A schematic diagram of the structure of a quantum computer;

[0035] Figure 2This is a schematic diagram of the first structure of the coupling device of the superconducting quantum bit in the embodiment of the present application;

[0036] Figure 3 Several structural schematic diagrams of the first superconducting quantum bit in the embodiments of the present application;

[0037] Figure 4 This is a structural schematic diagram of a first coupling module in an embodiment of the present application;

[0038] 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;

[0039] 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;

[0040] Figure 6 Schematic diagrams of several structures of the second superconducting quantum bit in the embodiments of the present application;

[0041] Figure 7 This is a schematic diagram of a first implementation of an adjustable coupling module in an embodiment of the present application;

[0042] Figure 8 Several structural schematic diagrams of adjustable couplers and fixed couplers in the embodiments of the present application;

[0043] Fig. 9 This is a schematic diagram of a first structure of the second coupling module in an embodiment of the present application;

[0044] Fig.10 This is a schematic diagram of a second implementation of the adjustable coupling module in the embodiment of the present application;

[0045] Fig.11 This is a second structural schematic diagram of the second coupling module in an embodiment of the present application;

[0046] Fig.12 This is a schematic diagram of the first structure of the superconducting quantum chip in the embodiment of the present application;

[0047] Fig.13 This is a schematic diagram of the second structure of the superconducting quantum chip in the embodiment of the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application provide a superconducting quantum bit coupling device, a superconducting quantum chip, and a quantum computer, which simplifies the adjustment method for realizing the coupling and disconnection between two superconducting quantum bits, realizes the full-band coupling and disconnection of two superconducting quantum bits, and provides greater freedom for the frequency allocation of multiple superconducting quantum bits. In addition, this design is also conducive to suppressing high-energy level leakage and improving the fidelity of parallel logic gates in the superconducting quantum bit coupling device.

[0049] It should be noted that the terms "first", "second", etc. (if any) in the specification and claims of the present 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 data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" and "having" and any of their variations 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 that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0050] This application can be mainly applied to superconducting quantum computing scenarios. 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 work 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. The energy levels and couplings of quantum bits can be designed and controlled very flexibly, and have great potential for scalability. The following is an introduction to quantum computers in superconducting quantum computing scenarios.

[0051] Figure 1 This is a schematic diagram of the structure of a quantum computer. Figure 1 As shown, the quantum computer includes: a dilution refrigerator for providing a low-temperature environment, a superconducting quantum chip for realizing quantum computing information carriers, and a measurement and control system for manipulating the state of quantum bits to perform computing operations and read the state of quantum bits. The superconducting quantum chip is placed in a low-temperature environment, and the measurement and control system controls the microwave source and modulates the pulse signal according to the needs of the computing operation, inputs a series of microwave pulse sequences into the superconducting quantum chip, and operates the bit quantum state. After all operations are completed, the measurement and control system outputs a measurement pulse signal to the superconducting quantum chip, obtains the state of the superconducting quantum bit through the returned signal, and obtains the calculation result. Further, as Figure 1 As shown, the superconducting quantum chip includes a plurality of coupling devices of superconducting quantum bits arranged in a two-dimensional array. The coupling device of each superconducting quantum bit includes two superconducting quantum bits and a coupler located between the two superconducting quantum bits, wherein the superconducting quantum bit refers to a superconducting resonant circuit including nonlinear components. It should be understood that Figure 1 The two-dimensional array arrangement shown is only a specific example. In practical applications, superconducting quantum chips can also be arranged in other forms, such as triangular arrays and hexagonal lattice arrays, etc., which are not limited here. The coupling device of the superconducting quantum bit is introduced in detail below.

[0052] It should be noted that in some existing schemes, two superconducting qubits are coupled through a traditional adjustable 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 adjustable 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, thereby realizing the coupling shutdown between the two superconducting qubits. However, we found that the cancellation of the two terms in the above equation is related to the frequency of the two superconducting qubits and the frequency of the adjustable coupler. If the frequency of the superconducting qubit changes, or the superconducting qubit leaks to a high energy level, the coupling shutdown condition will not be met. This feature poses a severe challenge to both multi-bit automatic calibration and parallel gates.

[0053] Figure 2 Schematic diagram of the first structure of the coupling device of superconducting quantum bits in the embodiment of the present application. Figure 2 As shown, 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. 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.

[0054] 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 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.

[0055] In short, the coupling off condition between the two superconducting qubits is that the coupling strength between the two resonant circuits of the adjustable coupling module 30 and the first superconducting qubit 10 has opposite signs and the same or similar magnitudes, and 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 magnitudes. The equivalent coupling strength between the first superconducting qubit 10 and the second superconducting qubit 20 is expressed as:

[0056]

[0057] Among them, Δ icj =ω i -ω cj represents the detuning between the i-th superconducting qubit 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 eff 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 information stored in the super quantum bit. It should be understood that in practical applications, ω c1 With ω c2Similar but not identical, that is, ω c1 With ω c2 The absolute value of the difference between is less than a second preset value, for example, the second preset value may be 500 MHz. Furthermore, the coupling disconnection between the two superconducting qubits may be understood as the coupling strength between the two superconducting qubits being less than a certain threshold.

[0058] It should be noted that the present application adjusts the frequency of the first resonant circuit to be the same 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, the coupling and shutoff between the two superconducting quantum bits 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 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, thus supporting high-fidelity multi-bit parallel gates.

[0059] It should be understood that the design of the present application can make the impedance of the first resonant circuit 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 off condition. Accordingly, it is necessary to design each component of the coupling device of the superconducting quantum bit in a targeted manner, which is described in detail below.

[0060] For the first superconducting quantum bit 10, Figure 2 As shown, the first superconducting quantum bit 10 includes an electrode 101, an electrode 102 and an inductor circuit 103, and the electrode 101 is connected to the electrode 102 through the inductor circuit 103. Among them, the electrode 101 and the electrode 102 are not grounded, and the first superconducting quantum bit 10 can also be called a double-electrode floating superconducting quantum bit. The inductor circuit 103 can be an inductive circuit composed of a plurality of linear inductors and a plurality of Josephson junctions connected in series, in parallel, or in a series-parallel mixture.

[0061] It should be understood that in order to achieve the above-mentioned coupling off condition, the coupling strength between the two resonant circuits of the adjustable coupling module 30 and the first superconducting quantum bit 10 has opposite signs and the same or similar magnitudes, the first resonant circuit is coupled to the electrode 101 through the first coupling module 40, and the second resonant circuit is coupled to the electrode 102 through the first coupling module 40, and when the first superconducting quantum bit 10 is in a resonant state, the voltage on the electrode 101 and the voltage on the electrode 102 are opposite in sign, wherein the first superconducting quantum bit 10 in a resonant state can also be referred to as the first superconducting quantum bit 10 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 the third preset value, for example, the third preset value may be 50fF.

[0062] Figure 3 Schematic diagrams of several structures of the first superconducting quantum bit in the embodiment of the present application. Figure 3 As shown, the types of the first superconducting quantum bit 10 include fixed-frequency Transmon, adjustable Transmon, capacitor-shunt flux bit, linear inductor Fluxonium bit and large-junction series Fluxonium bit. Among them, the fixed-frequency Transmon has a longer dephasing time, 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 capacitor-shunt flux quantum bit can be adjusted to be 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 what type of the first superconducting quantum bit is, it includes two ungrounded electrodes, and the difference in the inductance circuit determines the type of the first superconducting quantum bit 10. Generally speaking, Figure 3 The sizes of all capacitors 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.

[0063] Figure 4 FIG. 1 is a schematic diagram of a structure of the first coupling module in an embodiment of the present application. Figure 4 As shown, 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.

[0064] FIG5(a) is a schematic diagram of the second structure of the coupling device of the superconducting quantum bit in the embodiment of the present application. FIG5(b) is a schematic diagram of the third structure of the coupling device of the superconducting quantum bit in the embodiment of the present application. For the second superconducting quantum bit 20, as an example, the second superconducting quantum bit 20 can be a single electrode grounding structure as shown in FIG5(a), that is, the second superconducting quantum bit 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 through 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-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, 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.

[0065] Figure 6 Schematic diagrams of several structures of the second superconducting quantum bit in the embodiment of the present application. Figure 6 As shown, regardless of whether the second superconducting quantum bit 20 adopts a single-electrode grounding 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 inductance circuits determines the type of the second superconducting quantum bit 20. Generally speaking, the sizes of all capacitors in Figure 5 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.

[0066] 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 an adjustable inductor and / or an adjustable capacitor. Several possible implementations of the adjustable coupling module 30 are described below.

[0067] In a possible implementation, the adjustable coupling module 30 includes two independent single-mode circuits, each of which has multiple options. For example, the independent single-mode circuit is a fixed coupler or an adjustable coupler.

[0068] Figure 7 Schematic diagram of the first implementation of the adjustable coupling module in the embodiment of the present application. Figure 7 As shown in (a) in FIG. 1 , 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. Figure 7 As shown in (b) in FIG. 3 , 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 the 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.

[0069] Figure 8 Schematic diagrams of several structures of adjustable couplers and fixed couplers in the embodiments of the present application. Figure 8 As shown, whether it is an adjustable coupler or a fixed coupler, its specific types include grounded couplers, floating same-end couplers, floating different-end couplers and transmission line couplers. Generally speaking, Figure 8 All capacitors 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, all transmission line characteristic impedances are within the range of 1Ω to 1000Ω, and transmission line lengths are within the range of 100μm to 100mm. Figure 8 The two types of floating type or transmission line type couplers can make the specific size of the coupler longer, which helps to increase the distance between the two superconducting quantum bits, thereby increasing the wiring space and improving scalability. At the same time, longer couplers can also be used for long-distance coupling across chips.

[0070] Fig. 9 FIG. 1 is a schematic diagram of the first structure of the second coupling module in the embodiment of the present application. It should be understood that if the adjustable coupling module 30 adopts the above Figure 7 In the embodiment shown in the figure, the second coupling module 50 adopts Fig. 9Specifically, 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. 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 coupling strength between the two resonant circuits of the adjustable coupling module 30 and the second superconducting quantum bit 20 in the above-mentioned coupling off condition with the same sign and the same or similar size.

[0071] As an example, if the second superconducting quantum bit 20 adopts the single electrode grounding structure as shown in FIG. 5( a), the second coupling module 50 adopts Fig. 9 The first resonant circuit of the adjustable coupling module 30 is coupled to the electrode 201 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 the electrode 201 of the second superconducting quantum bit 20 through the capacitor 502 .

[0072] As another example, if the second superconducting quantum bit 20 adopts a double-electrode floating structure as shown in FIG. 5( b ), the second coupling module 50 adopts Fig. 9 The structure shown in (b). The first resonant circuit of the adjustable coupling module 30 is coupled to the electrode 203 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 the electrode 203 of the second superconducting quantum bit 20 through the 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, and the absolute value of the difference between the two parasitic capacitors 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.

[0073] In another possible implementation, the first resonant circuit and the second resonant circuit of the adjustable coupling module 30 have a common circuit structure, and this part of the common circuit structure is coupled to the second superconducting qubit 20 through the second coupling module 50 .

[0074] Fig.10 FIG. 2 is a schematic diagram of a second implementation of the adjustable coupling module in the embodiment of the present application. Fig.10 Several specific designs of the adjustable coupling module 30 are provided as shown. For example, the adjustable coupling module 30 is Fig.10 The single tunable TCQ (Tunable coupling qubit) coupler shown in (a) Fig.10 The dual tunable TCQ coupler shown in (b) Fig.10 The single tunable shared transmission line coupler shown in (c) or Fig.10 The dual adjustable shared transmission line coupler shown in (d) is shown in Fig. Fig.10 Each circuit structure shown includes three nodes, two of which are located on the same side, and the other node is located on the other side. The two nodes on the same side are coupled to the first superconducting quantum bit 10 through the first coupling module 40, and the node on the other side is coupled to the second superconducting quantum bit 20 through the second coupling module 50. It should be understood that the part of the circuit connected to the 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 Fig.10 The single-tunable type couplers shown in (a) and (c) are couplers in which only one resonant circuit frequency is tunable. Fig.10 The dual tunable type couplers shown in (b) and (d) are where the frequencies of both resonant circuits are tunable.

[0075] Generally speaking, Fig.10 All capacitors 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, all transmission line characteristic impedances are within the range of 1Ω to 1000Ω, and transmission line lengths are within the range of 100μm to 100mm. Fig.10 The floating type shown in (a) and (b) or Fig.10 The transmission line type couplers shown in (c) and (d) can make the specific size of the coupler longer, which helps to increase the distance between the two superconducting quantum bits, thereby increasing the wiring space and improving scalability.

[0076] Fig.11 FIG. 2 is a schematic diagram of a second structure of the second coupling module in the embodiment of the present application. It should be understood that if the adjustable coupling module 30 adopts the above Fig.10 In the embodiment shown in the figure, the second coupling module 50 adopts Fig.11 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 coupled to one of the electrodes of the second superconducting quantum bit 20 through the capacitor 505. That is, 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 to Fig. 9 The method shown, using Fig.11 The approach shown makes it easier to achieve the coupled off condition.

[0077] As an example, if the second superconducting quantum bit 20 adopts the single electrode grounding structure as shown in FIG. 5( a), the second coupling module 50 adopts Fig.11 The first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are coupled to the electrode 201 of the second superconducting quantum bit 20 via the capacitor 505 .

[0078] As another example, if the second superconducting quantum bit 20 adopts a double-electrode floating structure as shown in FIG. 5( b ), the second coupling module 50 adopts Fig.11 The structure shown in (b). The first resonant circuit and the second resonant circuit of the adjustable coupling module 30 are coupled to the electrode 203 of the second superconducting quantum bit 20 through the capacitor 505. In this example, the second coupling module 50 also 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, and the parasitic capacitor 506 is smaller than the capacitor 503, so as to achieve the coupling strength between the two resonant circuits of the adjustable coupling module 30 and the second superconducting quantum bit 20 in the above-mentioned coupling off condition with the same sign and the same or similar size.

[0079] It should be noted that, based on the coupling device of the superconducting quantum bit introduced above, a plurality of coupling devices of the superconducting quantum bits are arranged in a two-dimensional array to form a superconducting quantum chip. The following is an introduction to the possible distribution of the coupling devices of the superconducting quantum bits in the superconducting quantum chip. It should be understood that since the square grid array is the most widely used, the following mainly provides an implementation method for the square grid array arrangement.

[0080] Fig.12 Schematic diagram of the first structure of the superconducting quantum chip in the embodiment of the present application. Fig.12 As shown, 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 double-electrode floating ground design. It can be seen that the coupling device of each adjacent two superconducting quantum bits shares one superconducting quantum bit. As an example, Fig.12 As shown in Example 1 in , the coupling devices of two adjacent superconducting qubits share the first superconducting qubit. As another example, Fig.12 As shown in Example 2 in , the coupling devices of two adjacent superconducting qubits share the second superconducting qubit. As another example, Fig.12As shown in Example 3, the superconducting qubit shared by the coupling device of two adjacent superconducting qubits is the first superconducting qubit in the coupling device of one of the superconducting qubits, and is the second superconducting qubit in the coupling device of another superconducting qubit. 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, every two adjacent superconducting qubits in the superconducting quantum chip are coupled through a coupler. Moreover, for any superconducting qubit, the superconducting qubit can be used 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 is 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.

[0081] Fig.13 Schematic diagram of the second structure of the superconducting quantum chip in the embodiment of the present application. Fig.13 As shown, the first superconducting qubit adopts a dual-electrode floating design. It should be noted that the first electrode 101 of the first superconducting qubit includes two sub-electrodes 1 connected to each other and placed in a cross pattern, and the second electrode 102 of the first superconducting qubit includes two sub-electrodes 2 connected to each other and placed in a cross pattern. 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 qubits shares one superconducting qubit. As an example, Fig.13 As shown in Example 1 in , the coupling devices of two adjacent superconducting qubits share the first superconducting qubit. As another example, Fig.13 As shown in Example 2, the coupling devices of two adjacent superconducting qubits share the second superconducting qubit. It should be understood that this embodiment does not limit the design method adopted by the second superconducting qubit. For example, the second superconducting qubit can choose a grounded or floating design. For this embodiment, the two electrodes of the first superconducting qubit are designed as four cross-distributed sub-electrodes, which ensures that the coupling device of each superconducting qubit that shares the first superconducting qubit can utilize one set of sub-electrodes 1 and sub-electrode 2, and the overall symmetry of the superconducting quantum chip is good.

[0082] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application is described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the 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 and 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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