Quantum chip, method and quantum computer for controlling superconducting quantum bits

Abstract

The present invention belongs to the field of quantum computing technology, and relates to a quantum chip, method and quantum computer for controlling superconducting quantum bits, including: a duplexer, a coupling capacitor, an inductor and a quantum bit; one end of the duplexer is connected to an input signal, and the other end of the duplexer is respectively connected to an input end of the coupling capacitor and an input end of the inductor, for inputting a high-frequency XY control signal and a low-frequency Z control signal of the input signal into the coupling capacitor and the inductor respectively, the output end of the coupling capacitor is connected to the capacitor of the quantum bit, and the output end of the inductor is grounded and forms mutual inductance coupling with a superconducting quantum interference device. It can solve the decoherence problem caused by the high-frequency XY control signal and the low-frequency Z control signal mixing together to drive the quantum bit after the control signal enters the quantum chip in the prior art.

Description

Technical Field

[0001] The present invention relates to a quantum chip, method and quantum computer for controlling superconducting quantum bits, and belongs to the technical field of quantum computing. Background Art

[0002] Frequency-adjustable superconducting quantum bits require two control channels, one is a high-frequency control channel, which controls the XY rotation of the superconducting quantum bit through capacitive coupling; the other is a low-frequency control channel, which quickly biases the superconducting quantum interference device (SQUID) of the quantum bit through inductive coupling to change its equivalent inductance, thereby changing the frequency of the quantum bit and realizing the Z-axis rotation of the bit. Usually, these two control signals are divided into two paths, passing through different coaxial lines from room temperature through a series of attenuators and filters distributed in different temperature zones of the dilution refrigerator to reach the quantum chip at an extremely low temperature of about 10mK. However, this simple method requires more and more coaxial control channels as the number of bits integrated in the quantum chip increases rapidly, which greatly increases the space demand in the dilution refrigerator. In addition, as the number of bits increases, the fan-out and packaging of the control lines of the quantum chip become increasingly difficult.

[0003] Since the frequency ranges of these two control signals are very different, the high-frequency XY control channel is generally around 5GHz, while the low-frequency Z control channel signal is generally in the DC-1GHz range, so it can be achieved through frequency multiplexing. However, after the control signal generated by frequency multiplexing enters the quantum chip, the existing technology mixes the high-frequency XY control signal and the low-frequency Z control signal together to drive the quantum bit, wherein the high-frequency XY control signal is coupled to the capacitor of the quantum bit through capacitance, and the low-frequency Z control signal is coupled to the SQUID of the quantum bit through inductance, but there is still crosstalk between the two. Since the resonance frequency of the low-frequency Z control signal and the bit is very different, it will not cause the XY direction of the quantum bit to rotate. However, the high-frequency XY control signal will be coupled to the SQUID together with the low-frequency Z control signal, quickly changing the magnetic flux of the SQUID, thereby quickly modulating the frequency of the superconducting quantum bit, causing additional sideband driving effects, causing the superconducting quantum bit to couple to other systems of different frequencies, thereby causing decoherence. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a quantum chip, method and quantum computer for controlling superconducting quantum bits, which can solve the decoherence problem in the prior art caused by the high-frequency XY control signal and the low-frequency Z control signal mixing together to drive the quantum bit after the control signal enters the quantum chip.

[0005] To achieve the above-mentioned purpose, the present invention proposes the following technical scheme: a quantum chip for controlling a superconducting quantum bit, comprising: a duplexer, a coupling capacitor, an inductor and a quantum bit; one end of the duplexer is connected to an input signal, and the other end of the duplexer is respectively connected to an input end of the coupling capacitor and an input end of the inductor, so as to input a high-frequency XY control signal and a low-frequency Z control signal of the input signal into the coupling capacitor and the inductor respectively, the output end of the coupling capacitor is connected to a bit capacitor, the output end of the inductor is grounded, and forms mutual inductance coupling with the superconducting quantum interference device of the bit.

[0006] Furthermore, one end of the bit capacitor is connected to the output end of the coupling capacitor, and the other end of the bit capacitor is grounded. The low-frequency Z control signal processing module includes a superconducting quantum interference device, which is connected to the output end of the inductor to form a closed loop.

[0007] Furthermore, an output terminal of the inductor is grounded.

[0008] Furthermore, the duplexer includes: a first impedance converter and a second impedance converter; wherein one end of the first impedance converter is used to access the high-frequency XY control signal, and the other end of the first impedance converter is connected to the input end of the coupling capacitor; one end of the second impedance converter is used to access the low-frequency Z control signal, and the other end of the second impedance converter is connected to the input end of the inductor.

[0009] Furthermore, the first impedance converter and the second impedance converter are both coplanar waveguide impedance converters; and the lengths of the first impedance converter and the second impedance converter are both about one quarter of the wavelength corresponding to the quantum bit operating frequency.

[0010] Furthermore, the wire lengths of the first impedance converter and the second impedance converter are consistent or nearly consistent, and the wire lengths of the first impedance converter and the second impedance converter are determined by the operating frequency of the superconducting quantum bit and the dielectric constant of the substrate.

[0011] The present invention also discloses a quantum computer, comprising a control system, a cryogenic transmission system and any one of the above quantum chips; the control system and the quantum chip are connected via the cryogenic transmission system signal.

[0012] The present invention also discloses a method for controlling a superconducting quantum bit, which adopts any of the above-mentioned quantum chips, and comprises the following steps: inputting XY and Z mixed signals into the quantum chip, and then dividing the input mixed signals into two outputs of a high-frequency XY control signal and a low-frequency Z control signal through the above-mentioned duplexer; coupling the high-frequency XY control signal to the bit capacitor to realize the XY-axis rotation control of the quantum bit; and coupling the low-frequency Z control signal to the superconducting quantum interference device to realize the Z-axis rotation control of the quantum bit.

[0013] Furthermore, when the frequency of the input signal is in the low frequency band, the high frequency XY control signal branch is an open circuit, the low frequency Z control signal branch is a short circuit, and the low frequency Z control signal is coupled to the superconducting quantum interference device to bias the magnetic flux of the superconducting quantum interference device to change the frequency of the superconducting quantum bit, thereby realizing Z-axis rotation control.

[0014] Furthermore, when the frequency of the input signal is close to the operating frequency of the superconducting quantum bit, the Z-axis rotation control signal branch is high impedance, the input signal enters the high-frequency XY control signal branch, and the high-frequency XY control signal is coupled to the bit capacitor to realize the XY-axis rotation control of the superconducting quantum bit.

[0015] The present invention adopts the above technical solution, which has the following advantages:

[0016] 1. The present invention divides the high-frequency XY control signal and the low-frequency Z control signal into two output paths through a duplexer, and then couples the high-frequency XY control signal to the capacitor of the quantum bit to realize the XY axis rotation control, and couples the low-frequency Z axis control signal to the superconducting quantum interference device of the quantum bit to realize the Z axis rotation control. The two do not interfere with each other, and avoid the high-frequency XY control signal and the low-frequency Z control signal being mixed together after entering the quantum chip and coupled to the superconducting quantum interference device to cause additional sideband driving effect, thereby avoiding the decoherence problem caused by the superconducting quantum bit coupling to other different frequency systems.

[0017] 2. The present invention uses a simple duplexer consisting of two quarter-wavelength (λ / 4) impedance converters to control superconducting quantum bits. The duplexer has a simple structure, is compatible with the micro-nano processing technology of quantum chips, and can be directly integrated on quantum chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a circuit schematic diagram of a duplexer and a quantum bit in a quantum chip in one embodiment of the present invention;

[0019] Figure 2 is a working principle diagram of a duplexer controlling a quantum bit in one embodiment of the present invention;

[0020] Figure 3 It is a flow chart of a method for controlling superconducting quantum bits in one embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the provision of specific embodiments is only for a better understanding of the present invention, and they should not be understood as limitations of the present invention. In the description of the present invention, it should be understood that the terms used are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0022] Superconducting qubits are a controllable artificial atomic system based on superconducting Josephson structures. Compared with other quantum computing systems, superconducting qubits have the advantages of strong design controllability, good scalability, easy coupling and easy manipulation. The control of qubits is mainly achieved through qubit gates, which can be divided into single-qubit gates, two-qubit gates and multi-qubit gates. Single-qubit gates in superconducting quantum computing can be divided into XY manipulation and Z manipulation. XY manipulation can be achieved by microwave signals acting on superconducting qubits in a capacitive coupling manner; Z manipulation can be achieved by using a DC Z control signal to generate magnetic flux through a superconducting quantum interferometer SQUID ring to act on superconducting qubits, or by adding phase offsets to all subsequent manipulation microwave pulses in a virtual Z manipulation manner.

[0023] In order to solve the decoherence problem existing in the prior art that the high-frequency XY control signal will be coupled to the SQUID together with the low-frequency Z control signal. The present invention proposes a quantum chip, method and quantum computer for controlling superconducting quantum bits, which outputs the high-frequency XY control signal and the low-frequency Z control signal of the input signal in two ways through a duplexer; couples the high-frequency XY control signal to the bit capacitor to realize the XY axis rotation control of the quantum bit; and couples the low-frequency Z control signal to the superconducting quantum interference device to realize the Z axis rotation control of the quantum bit. As a result, the high-frequency XY control signal and the low-frequency Z control signal do not interfere with each other, thereby avoiding the decoherence problem caused by crosstalk between high and low frequency signals. The scheme of the present invention is described in detail below through several embodiments in conjunction with the accompanying drawings.

[0024] Embodiment 1

[0025] This embodiment discloses a quantum chip for controlling superconducting quantum bits, such as Figure 1 As shown, it includes: a duplexer, a coupling capacitor C1, an inductor L1, a quantum bit and a substrate; one end of the duplexer is connected to the input signal, and the other end of the duplexer is respectively connected to the input end of the coupling capacitor C1 and the input end of the inductor, for inputting the high-frequency XY control signal and the low-frequency Z control signal of the input signal into the coupling capacitor C1 and the inductor respectively, and the output end of the coupling capacitor C1 is connected to the bit capacitor, for coupling the high-frequency XY control signal to the quantum bit, and the output end of the inductor is grounded and forms a mutual inductance coupling with the superconducting quantum interference device, for changing the magnetic flux of the superconducting quantum interference device, thereby realizing the Z rotation of the quantum bit. The duplexer, coupling capacitor C1, inductor L1 and quantum bit are all arranged on the substrate. The substrate material can be silicon, sapphire, etc. In specific use, those skilled in the art can select appropriate materials as needed, without limitation here.

[0026] In this embodiment, the duplexer includes: a first impedance converter and a second impedance converter; wherein one end of the first impedance converter, i.e., the input end A of the duplexer, is used to access the high-frequency XY control signal, and the other end of the first impedance converter is connected to the input end of the coupling capacitor C1, and is used to couple the high-frequency XY control signal to the bit capacitor C2 through the coupling capacitor C1. One end of the second impedance converter, i.e., the input end A of the duplexer, is used to access the low-frequency Z control signal, and the other end of the second impedance converter is connected to the input end of the inductor, and is used to couple the low-frequency Z control signal to the superconducting quantum interference device SQUID through the inductor L1.

[0027] In this embodiment, the first impedance converter and the second impedance converter are preferably coplanar waveguide impedance converters, but other existing impedance converters may also be used, and are not limited thereto. The lengths of the first impedance converter and the second impedance converter are both about one-quarter of the wavelength corresponding to the operating frequency of the quantum bit. The length of the wires of the first impedance converter and the second impedance converter are consistent. The consistency of the length here does not mean that the lengths must be exactly the same, as long as the difference in length between the two is within an allowable range. The length of the wires of the first impedance converter and the second impedance converter is determined by the operating frequency of the superconducting quantum bit and the dielectric constant of the substrate.

[0028] After the high-frequency XY control signal and the low-frequency Z control signal of the input signal are output in two paths at the input end, the other end of the high-frequency XY control signal branch is open, and the high-frequency XY control signal is coupled to the bit capacitor C2 through the coupling capacitor C1 to realize XY axis rotation control, and the other end of the low-frequency Z control signal branch is short-circuited, and the low-frequency Z control signal is coupled to the superconducting quantum interference device SQUID through the inductor L1 to realize Z axis rotation control.

[0029] Among them, when the frequency of the input signal is in the low frequency band, the high-frequency XY control signal branch is open circuit, the low-frequency Z control signal branch is short circuit, and the low-frequency Z control signal is coupled to the superconducting quantum interference device to bias the magnetic flux of the superconducting quantum interference device to change the frequency of the superconducting quantum bit, thereby realizing Z-axis rotation control. When the input signal is close to the operating frequency of the superconducting quantum bit, the low-frequency Z control signal branch is high impedance, the input signal enters the high-frequency XY control signal branch, and the high-frequency XY control signal is coupled to the bit capacitor to realize the XY axis rotation control of the superconducting quantum bit.

[0030] like Figure 2As shown, the working principle of the duplexer controlling the superconducting quantum bit is explained by taking the input signal connected to the input end of the duplexer as a signal with a voltage of Vin and a current of Iin as an example. First, calculate the signal strength ratio Vxy / Vin of the voltage Vxy at the coupling capacitor C1 and the input voltage Vin, and the signal strength ratio Iz / Iin of the current Iz at the inductor L1 and the input current Iin. The relationship between the ratio and the input signal frequency is shown in Figure 2 As shown in the figure, when the input signal frequency is low, the high-frequency XY control signal branch is equivalent to an open circuit, and the low-frequency Z control signal branch is equivalent to a short circuit, so Vxy is extremely small, and Iz is very large, which can effectively bias the magnetic flux of the superconducting quantum interference device. Due to the superposition of the total reflection signal and the input signal, Iz is approximately equal to 2 times Iin, that is, 6dB (as shown by the dotted line in the figure). Near the operating frequency of the superconducting quantum bit (taking 5GHz as an example), due to the characteristics of the quarter coplanar waveguide impedance converter, the low-frequency Z control signal branch impedance is close to infinity, so the Iz end can be regarded as an open circuit, and the input signal mainly enters the Vxy end. When the input signal wavelength is completely matched with the first impedance converter IT1, the total reflection signal is superimposed on the input signal, so that Vxy is equal to 2 times Vin, that is, 6dB, so the high-frequency XY control signal can effectively realize the XY axis rotation control of the superconducting quantum bit through the coupling capacitor C1; at the same time, the current Iz of the low-frequency Z control signal branch is extremely small, so the high-frequency XY signal can be avoided. Rapid modulation of the superconducting quantum interference device.

[0031] Therefore, after entering the quantum chip, the present invention sets a duplexer to couple the high-frequency XY control signal to the bit capacitor through capacitance, and couples the low-frequency Z control signal to the superconducting quantum interference device through inductance, while avoiding the mutual crosstalk between the two, that is, avoiding the high-frequency XY control signal to be coupled to the superconducting quantum interference device SQUID together with the low-frequency Z control signal to quickly bias the SQUID magnetic flux, thereby quickly modulating the superconducting quantum bit frequency. The additional sideband driving effect caused, that is, avoiding the decoherence problem caused by the superconducting quantum bit coupling to other different frequency systems. In addition, the duplexer provided by the present invention has a simple structure, is compatible with the micro-nano processing technology of the quantum chip, and can be directly integrated on the quantum chip.

[0032] Embodiment 2

[0033] Based on the same inventive concept, this embodiment discloses a quantum computer, including a control system, a cryogenic transmission system and any of the above quantum chips; the control system and the quantum chip are connected by a cryogenic transmission system signal. The cryogenic transmission system includes a cryogenic microwave circuit, and the control system and the quantum chip are connected by a cryogenic microwave circuit. Among them, the control system is generally placed in the room temperature area, and a duplexer is used to merge the high and low frequency signals at room temperature, and then the signal is transmitted to the quantum chip through a coaxial line to control the quantum bit. Through a coaxial line and a quantum chip placed in the cryogenic transmission system, a complete control of a superconducting quantum bit including XY axis rotation and Z axis rotation can be achieved. This method can save half of the control line channel and has significant advantages for multi-bit quantum chips. Its main working principle is: a vector signal generator is used to generate a microwave control signal, and an arbitrary wave generator is used to generate a gate signal. The above two control signals are transmitted to the quantum chip through a cryogenic microwave circuit, so as to perform frequency tuning, state flipping and energy level transition operations on the quantum bit. ADC (analog / digital converter) is used to collect and process quantum signals. The quantum signal of the quantum bit is transmitted to the ADC via the cryogenic microwave circuit to read the quantum bit information. The cryogenic transmission system may include a refrigeration component (such as a refrigerator) to provide a low-temperature environment for the cryogenic microwave circuit and the quantum chip 01, thereby creating superconducting conditions for the cryogenic microwave circuit and the quantum chip to prevent adverse effects such as thermal noise.

[0034] Embodiment 3

[0035] Based on the same inventive concept, this embodiment discloses a method for controlling a superconducting quantum bit, such as Figure 3 As shown, a quantum chip using any of the above items comprises the following steps:

[0036] The S1 input signal is divided into two outputs, a high-frequency XY control signal and a low-frequency Z control signal, through a duplexer;

[0037] Among them, the quantum chip includes: a duplexer, a coupling capacitor C1, an inductor L1, a quantum bit and a substrate; one end of the duplexer is connected to the input signal, and the other end of the duplexer is respectively connected to the input end of the coupling capacitor C1 and the input end of the inductor, for inputting the high-frequency XY control signal and the low-frequency Z control signal of the input signal into the coupling capacitor C1 and the inductor respectively, and the output end of the coupling capacitor C1 is connected to the bit capacitor, for coupling the high-frequency XY control signal to the quantum bit, and the output end of the inductor is grounded and forms a mutual inductance coupling with the superconducting quantum interference device SQUID, for controlling the magnetic flux of the superconducting quantum interference device SQUID. The duplexer, coupling capacitor C1, inductor L1 and quantum bit are all arranged on the substrate. The substrate material can be silicon, sapphire, etc. In specific use, those skilled in the art can select appropriate materials as needed, without limitation here.

[0038] In this embodiment, the duplexer includes: a first impedance converter and a second impedance converter; wherein one end of the first impedance converter, i.e., the input end A of the duplexer, is used to access the high-frequency XY control signal, and the other end of the first impedance converter is connected to the input end of the coupling capacitor C1, and is used to couple the high-frequency XY control signal to the bit capacitor C2 through the coupling capacitor C1. One end of the second impedance converter, i.e., the input end A of the duplexer, is used to access the low-frequency Z control signal, and the other end of the second impedance converter is connected to the input end of the inductor, and is used to couple the low-frequency Z control signal to the superconducting quantum interference device SQUID through the inductor L1.

[0039] In this embodiment, the first impedance converter and the second impedance converter are preferably coplanar waveguide impedance converters, but can also be impedance converters constructed of lumped components. The lengths of the first impedance converter and the second impedance converter are both about one-quarter of the wavelength corresponding to the operating frequency of the quantum bit. The wire lengths of the first impedance converter and the second impedance converter are consistent. The wire lengths of the first impedance converter and the second impedance converter are determined by the operating frequency of the superconducting quantum bit and the dielectric constant of the substrate. The length of the wire should be equal to one-quarter of the wavelength corresponding to the operating frequency of the superconducting quantum bit, which is generally 4-8 mm on a silicon substrate or a sapphire substrate.

[0040] S2 couples the high-frequency XY control signal to the bit capacitor to achieve XY axis rotation control of the quantum bit;

[0041] S3 couples the low-frequency Z control signal to the superconducting quantum interference device to achieve Z-axis rotation control of the quantum bit.

[0042] When the high-frequency XY control signal and the low-frequency Z control signal of the input signal are output in two paths at the input end, the other end of the high-frequency XY control signal branch is open, and the high-frequency XY control signal is coupled to the superconducting quantum bit through the coupling capacitor to realize XY axis rotation control. The other end of the low-frequency Z control signal branch is short-circuited, and the low-frequency Z control signal is coupled to the superconducting quantum interference device through induction to realize Z axis rotation control.

[0043] When the frequency of the input signal is in the low frequency band, the high-frequency XY control signal branch is an open circuit, and the low-frequency Z control signal branch is a short circuit. The low-frequency Z control signal is coupled to the superconducting quantum interference device to bias the magnetic flux of the superconducting quantum interference device to change the frequency of the superconducting quantum bit, thereby realizing Z-axis rotation control.

[0044] When the frequency of the input signal is close to the operating frequency of the superconducting quantum bit, the Z-axis rotation control signal branch is high impedance, the input signal enters the high-frequency XY control signal branch, and the high-frequency XY control signal is coupled to the bit capacitor to realize the XY-axis rotation control of the superconducting quantum bit.

[0045] It can be seen that in this embodiment, by dividing the high-frequency XY control signal and the low-frequency Z control signal into two outputs through a duplexer, the high-frequency XY control signal can be coupled to the bit capacitor of the superconducting quantum bit to realize XY axis rotation control, and the low-frequency Z axis control signal can be coupled to the superconducting quantum interference device SQUID of the superconducting quantum bit to realize Z axis rotation control. The two do not interfere with each other, avoiding the high-frequency XY control signal and the low-frequency Z control signal from mixing together and coupling to the superconducting quantum interference device SQUID after entering the quantum chip to cause additional sideband driving effect, thereby avoiding the decoherence problem caused by the superconducting quantum bit coupling to other different frequency systems.

[0046] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0047] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0048] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0049] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention should be included in the protection scope of the claims of the present invention. The above content is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A quantum chip for controlling superconducting quantum bits, characterized in that: include: duplexers, coupling capacitors, inductors, and qubits; One end of the duplexer is connected to the input signal, and the other end of the duplexer is respectively connected to the input end of the coupling capacitor and the input end of the inductor, so as to input the high-frequency XY control signal and the low-frequency Z control signal of the input signal into the coupling capacitor and the inductor respectively, the output end of the coupling capacitor is connected to the bit capacitor of the quantum bit, and the output end of the inductor is grounded and forms mutual inductance coupling with the superconducting quantum interference device SQUID of the quantum bit; One end of the bit capacitor of the quantum bit is connected to the output end of the coupling capacitor, and the other end of the bit capacitor is grounded; The duplexer includes: a first impedance converter and a second impedance converter; wherein one end of the first impedance converter is used to access the high-frequency XY control signal, and the other end of the first impedance converter is connected to the input end of the coupling capacitor; one end of the second impedance converter is used to access the low-frequency Z control signal, and the other end of the second impedance converter is connected to the input end of the inductor.

2. The quantum chip for controlling superconducting quantum bits according to claim 1, characterized in that: The first impedance converter and the second impedance converter are both coplanar waveguide impedance converters; the lengths of the first impedance converter and the second impedance converter are both one quarter of the wavelength corresponding to the quantum bit operating frequency.

3. The quantum chip for controlling superconducting quantum bits according to claim 2, characterized in that: The wire lengths of the first impedance converter and the second impedance converter are consistent, and the wire lengths of the first impedance converter and the second impedance converter are determined by the operating frequency of the superconducting quantum bit and the dielectric constant of the substrate.

4. A quantum computer, characterized in that: It comprises a control system, a low-temperature transmission system and a quantum chip as described in any one of claims 1 to 3; the control system and the quantum chip are connected through the signal of the low-temperature transmission system.

5. A method for controlling a superconducting quantum bit, characterized in that: Using the quantum chip as described in any one of claims 1 to 3, The following steps are involved: Inputting a mixed signal of XY and Z, and dividing the mixed signal of XY and Z into two outputs of a high-frequency XY control signal and a low-frequency Z control signal through the duplexer; Coupling the high frequency XY control signal to the capacitance of the quantum bit to achieve XY axis rotation control of the quantum bit; The low-frequency Z control signal is coupled to a superconducting quantum interference device to achieve Z-axis rotation control of the quantum bit.

6. The method for controlling a superconducting quantum bit according to claim 5, characterized in that: When the frequency of the input signal is in the low frequency band, the high-frequency XY control signal branch is an open circuit, and the low-frequency Z control signal branch is a short circuit. The low-frequency Z control signal is coupled to the superconducting quantum interference device to bias the magnetic flux of the superconducting quantum interference device to change the frequency of the superconducting quantum bit, thereby realizing Z-axis rotation control.

7. The method for controlling a superconducting quantum bit according to claim 5, characterized in that: When the frequency of the input signal is close to the operating frequency of the superconducting quantum bit, the Z-axis rotation control signal branch is high impedance, and the input signal enters the high-frequency XY control signal branch, and the high-frequency XY control signal is coupled to the bit capacitor to realize the XY-axis rotation control of the superconducting quantum bit.

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