Circulator and quantum computer

Abstract

This invention relates to the field of circulator technology, and discloses a circulator and a quantum computer. The circulator includes multiple superconducting cavities and at least one acoustic wave device. The superconducting cavities are microwave resonant cavities fabricated from superconducting materials. A first acoustic wave device generates acoustic waves, which propagate along a predetermined direction between the first and second superconducting cavities. The first and second superconducting cavities interact optically via the acoustic waves, causing the signal between them to propagate along a target propagation direction. The first and second superconducting cavities can be any two of the multiple superconducting cavities, and the first acoustic wave device is one of at least one acoustic wave device. The circulator provided by this invention does not contain a magnetic field, which can significantly reduce the manufacturing cost of the circulator, thereby reducing the development cost of a superconducting quantum computer.

Description

Technical Field

[0001] The present invention relates to the technical field of circulators, and in particular to a circulator and a quantum computer. Background Art

[0002] In superconducting quantum computing and quantum signal processing systems, a circulator is an important passive device that can achieve directional transmission of signals, ensuring that the signal can only flow in the set direction and cannot be transmitted in the opposite direction. Simply put, a circulator has three or more ports. For a signal input from one port, it will only be output to the next port, forming a loop direction, which can effectively isolate signals on different paths, prevent reflections and crosstalk, and thus ensure the stability of the system and the quality of the signal.

[0003] At present, microwave circulators are mainly based on the Faraday rotation effect of the rotation of the polarization plane when electromagnetic waves are transmitted in gyromagnetic ferrite materials (with an external DC magnetic field) to achieve unidirectional transmission of signals, that is, the circulators on superconducting quantum computers are made of magnetic materials. However, superconducting quantum chips are extremely sensitive to magnetic fields, which will reduce the performance of superconducting quantum bits. Therefore, very special shells are generally designed to prevent magnetic field leakage from affecting superconducting quantum chips, resulting in higher costs for the prepared circulators. Summary of the invention

[0004] In view of this, the present invention provides a circulator and a quantum computer to solve the problem of high cost of preparing the circulator.

[0005] In a first aspect, the present invention provides a circulator, comprising a plurality of superconducting cavities and at least one acoustic wave device, wherein the superconducting cavity is a microwave resonant cavity made of superconducting material; the first acoustic wave device is used to generate acoustic waves, the acoustic waves are transmitted along a preset direction between the first superconducting cavity and the second superconducting cavity, the first superconducting cavity and the second superconducting cavity interact with each other through the acoustic waves, so that the signal between the first superconducting cavity and the second superconducting cavity is transmitted along a target transmission direction, wherein the first superconducting cavity and the second superconducting cavity are any two of the plurality of superconducting cavities, and the first acoustic wave device is one of the at least one acoustic wave device.

[0006] In an optional embodiment, the circulator also includes an acoustic wave medium layer; the first acoustic wave device is arranged on the acoustic wave medium layer, the first superconducting cavity and the second superconducting cavity are connected through the acoustic wave medium layer in the preset direction, and the acoustic wave is transmitted along the acoustic wave medium layer.

[0007] In this embodiment, by transmitting sound waves through the acoustic wave medium layers located in the first superconducting cavity and the second superconducting cavity, the sound waves can be confined to a preset direction, the loss of the sound waves during the transmission process can be reduced, and the sound wave transmission efficiency can be improved.

[0008] In an optional embodiment, the target transmission direction is determined based on a signal transmission matrix of the center frequencies of the first superconducting cavity and the second superconducting cavity, wherein the center frequencies of the superconducting cavities are the same and the signal transmission matrix , the signal transmission matrix is ​​used to represent the probability of the signal being transmitted in each transmission direction, represents the probability of transmission in the transmission direction between the two ports of the first superconducting cavity, represents the probability of transmission in the transmission direction from the first superconducting cavity to the second superconducting cavity, represents the probability of transmission in the transmission direction from the second superconducting cavity to the first superconducting cavity, represents the probability of transmission in the transmission direction between the two ports of the second superconducting cavity, and the target transmission direction is the transmission direction corresponding to the maximum probability in the signal transmission matrix.

[0009] In this embodiment, the target transmission direction of the signal can be accurately determined through the signal transmission matrix.

[0010] In an optional implementation, the signal transmission matrix is ​​determined based on a coupling phase between the first superconducting cavity and the first acoustic wave device and a coupling phase between the second superconducting cavity and the first acoustic wave device.

[0011] In this embodiment, when preparing the circulator, the target transmission direction of the circulator can be flexibly adjusted by adjusting the coupling phase between the first superconducting cavity and the first acoustic wave device, or adjusting the coupling phase between the second superconducting cavity and the first acoustic wave device.

[0012] In an optional embodiment, the signal transmission matrix is ​​determined based on the coupling phase between the first superconducting cavity and the first acoustic wave device and the coupling phase between the second superconducting cavity and the first acoustic wave device, by the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity.

[0013] In an optional implementation, the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity is expressed by the following formula:

[0014]

[0015] The motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity is expressed by the following formula:

[0016]

[0017] in, d represents the differential operator, t represents the transmission time of the signal, represents an infinitesimal quantity, represents the photon annihilation operator in the first superconducting cavity, represents the decay rate of the superconducting cavity, represents a natural constant, represents an imaginary root, represents the coupling phase between the first superconducting cavity and the first acoustic wave device, represents the coupling phase between the second superconducting cavity and the first acoustic wave device, represents the coupling strength between the first superconducting cavity and the second superconducting cavity, represents the photon annihilation operator in the second superconducting cavity, , represents the effective coupling strength between the first superconducting cavity and the first acoustic wave device when the average number of multiphotons or photons in the first superconducting cavity is not 1, represents the attenuation rate of the first acoustic wave device, represents the frequency detuning between the first superconducting cavity and the first acoustic wave device, , represents the frequency of photons in the first superconducting cavity, represents the frequency of the phonon of the first acoustic wave device, Greater than .

[0018] In an optional implementation, the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity are determined by Hamiltonian.

[0019] In an optional implementation, the Hamiltonian is expressed by the following formula:

[0020]

[0021] in, represents the Hamiltonian, is Planck's constant, represents the generation operator of phonons and photons in the first acoustic wave device, represents the annihilation operator of phonons and photons in the first acoustic wave device, represents the amplitude of the signal in the first superconducting cavity, represents the amplitude of the signal in the second superconducting cavity, represents the photon generation operator in the first superconducting cavity, represents the photon generation operator in the second superconducting cavity, represents the optical force coupling strength between the first acoustic wave device and the first superconducting cavity, represents the optical force coupling strength between the first acoustic wave device and the second superconducting cavity.

[0022] In an optional embodiment, the and stated The attenuation rate is determined based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, wherein the attenuation rates of the plurality of superconducting cavities are the same.

[0023] In this embodiment, when preparing the circulator, the target transmission direction of the circulator can be flexibly adjusted by adjusting the attenuation rate of the first acoustic wave device and / or adjusting the attenuation rate of the first superconducting cavity.

[0024] In an optional embodiment, the Based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, the attenuation rate of the first superconducting cavity is determined by a first corresponding relationship. Based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, the second corresponding relationship is determined, wherein the first corresponding relationship is used to characterize The corresponding relationship between the frequency of the signal, the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, the second corresponding relationship is used to characterize The correspondence between the frequency of the signal, the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity.

[0025] In an optional implementation manner, the first corresponding relationship is expressed by the following formula:

[0026]

[0027] The second corresponding relationship is expressed by the following formula:

[0028]

[0029] in, represents the frequency of the signal, represents the attenuation rate of the first acoustic wave device, represents the decay rate of the superconducting cavity; the second corresponding relationship is expressed by the following formula.

[0030] In an optional implementation, the transmission bandwidth of the signal is determined based on the attenuation rate of the superconducting cavity.

[0031] In an optional embodiment, the first corresponding relationship is determined based on the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity, and the second corresponding relationship is determined based on the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity.

[0032] In an optional implementation manner, the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise is expressed by the following formula:

[0033]

[0034] The motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity under the influence of noise is expressed by the following formula:

[0035]

[0036] in, represents the differential operator, represents the transmission time of the signal, represents an infinitesimal quantity, represents the photon annihilation operator in the first superconducting cavity, represents the decay rate of the superconducting cavity, represents a natural constant, represents an imaginary root, represents the coupling phase between the first superconducting cavity and the first acoustic wave device, represents the coupling phase between the second superconducting cavity and the first acoustic wave device, represents the coupling strength between the first superconducting cavity and the second superconducting cavity, represents the photon annihilation operator in the second superconducting cavity, represents the coupling strength with external environmental noise, represents the input noise of the first superconducting cavity, represents the input noise of the first acoustic wave device, , represents the attenuation rate of the first acoustic wave device, Greater than , , , represents the input noise of the second superconducting cavity.

[0037] In an optional implementation, the absolute value of the difference between the center frequency of the superconducting cavity and the frequency of the signal is smaller than a preset value.

[0038] In an optional implementation, the number of the superconducting cavities is greater than or equal to 3, and the number of the acoustic wave devices is greater than or equal to 3.

[0039] In an optional implementation, the number of the superconducting cavities is 2, and the number of the acoustic wave devices is 1.

[0040] In an optional embodiment, the microwave resonant cavity is a coplanar waveguide resonant cavity, which includes a cavity, a central conductor, an input feeder port and an output feeder port; the cavity has a accommodating space; the central conductor is located in the accommodating space and is used to transmit signals; the input feeder port and the output feeder port are respectively located at two ends of the central conductor, a gap is provided between the central conductor and the input feeder port, a gap is provided between the central conductor and the output feeder port, the input feeder port is used to input signals into the central conductor, and the output feeder port is used to output the signals on the central conductor.

[0041] In an optional embodiment, the first acoustic wave device includes an acoustic wave transmitter and an acoustic wave reflector; the acoustic wave transmitter is located at one end of the first superconducting cavity in the preset direction, and is used to generate acoustic waves; the acoustic wave reflector is located at one end of the second superconducting cavity in the preset direction, and is used to adjust the transmission direction of the acoustic waves.

[0042] In a second aspect, the present invention provides a quantum computer, comprising a circulator as described in the first aspect or any corresponding embodiment thereof, wherein the circulator is connected to a superconducting quantum chip or a superconducting Josephson parametric amplifier for isolating signals in different transmission directions.

[0043] The circulator provided by the present invention generates non-reciprocity based on the interaction between sound waves and two superconducting cavities through optical force, so that signals can be transmitted unidirectionally in the two superconducting cavities without increasing the magnetic field. That is, the circulator provided by the present invention does not contain a magnetic field, which can greatly reduce the production cost of the circulator, and thus reduce the research and development cost of superconducting quantum computers. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 is a connection diagram of a circulator and a superconducting Josephson parametric amplifier according to an embodiment of the present invention;

[0046] Figure 2 It is a schematic diagram of the structure of a conventional circulator;

[0047] Figure 3 is a schematic structural diagram of a circulator according to an embodiment of the present invention;

[0048] Figure 4 According to an embodiment of the present invention, With the frequency of the signal A schematic diagram of the curve of the change of

[0049] Figure 5 According to an embodiment of the present invention, With the frequency of the signal A schematic diagram of the curve of the change of

[0050] Figure 6 Another embodiment of the present invention is With the frequency of the signal A schematic diagram of the curve of the change of

[0051] Figure 7 Another embodiment of the present invention is With the frequency of the signal A schematic diagram of the curve of the change of

[0052] Figure 8 According to another embodiment of the present invention With the frequency of the signal A schematic diagram of the curve of the change of

[0053] Fig. 9 According to another embodiment of the present invention With the frequency of the signal Schematic diagram of the curve of the change of .

[0054] Figure numerals: 110, superconducting Josephson parametric amplifier; 300, circulator; 311, superconducting cavity; 3111, cavity; 3111a, accommodating space; 3112, central conductor; 3113, input feeder port; 3114, output feeder port; 321, acoustic wave device; 3211, acoustic wave transmitter; 3212, acoustic wave reflector; 330, acoustic wave dielectric layer. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0056] In order to facilitate the understanding of the present invention, the terms involved in the present invention are first introduced.

[0057] (1) Circulator

[0058] A circulator, also called a circulator, is a non-reciprocal device with several ports. Generally, a circulator has several ports. The signal is transmitted to the next port in the direction determined by the static magnetic field, and can only be transmitted in this direction and cannot be transmitted in the reverse order. The circulator can isolate the signal from the noise and improve the quality of the test signal.

[0059] (2) Superconducting Josephson parametric amplifier

[0060] A superconducting Josephson Parametric Amplifier (S-JPA) is a quantum electronic device that uses the nonlinear characteristics of a superconducting Josephson junction to amplify signals (such as microwave signals). It is used to amplify weak quantum signals with low noise to maintain quantum coherence and achieve high-fidelity quantum operations.

[0061] The core of the superconducting Josephson parametric amplifier is the superconducting Josephson junction, which is a structure consisting of two layers of superconducting material separated by a very thin insulating layer (or weak link layer). In the superconducting state, the Josephson junction allows unimpeded superconducting current to pass through and exhibits unique nonlinear electrical properties. When a microwave signal (usually related to the manipulation frequency of the quantum bit) passes through the Josephson junction, the nonlinear response of the junction will change the phase and amplitude of the microwave signal. By appropriately modulating the external drive (pump) signal, parametric amplification of the input signal can be achieved.

[0062] In superconducting quantum computing or quantum communication systems, superconducting Josephson parametric amplifiers and circulators are usually integrated together in the readout link of quantum bits. The readout signal of the quantum bit first passes through the circulator to ensure that the signal can only be transmitted in one direction to the superconducting Josephson parametric amplifier for amplification, and will not be fed back to the quantum bit to affect its quantum state.

[0063] Exemplarily, the connection relationship between the superconducting Josephson parametric amplifier and the circulator can be as follows: Figure 1 As shown, since the superconducting Josephson parametric amplifier 110 has only one signal terminal, in order to reduce the interference between the input and output signals, a circulator 300 can be used to isolate the two signals (input signal and output signal).

[0064] (3) Superconducting quantum chip

[0065] Superconducting quantum chips refer to integrated circuits made of superconducting materials (such as niobium, aluminum, niobium nitride, etc.) and superconducting circuit technology for quantum information processing. Superconducting quantum chips usually contain a series of superconducting quantum bits (such as superconducting Josephson junction bits or Transmon bits) and necessary control and readout circuits to achieve quantum information tasks such as quantum computing, quantum simulation and quantum communication. Superconducting quantum chips operate on low-temperature platforms such as dilution refrigerators to maintain the operating temperature of superconducting quantum chips far below the critical temperature.

[0066] Superconducting qubits are the basic computing units of superconducting quantum chips, usually composed of superconducting Josephson junctions or their derivative structures). Superconducting qubits use the quantum properties of superconducting states (such as Cooper pairs, macroscopic quantum coherence, etc.) to encode and manipulate quantum information. The quantum state of a superconducting qubit is usually read out through its strong coupling with a superconducting resonant cavity. The resonant cavity acts as an interface between the qubit and the microwave signal, and the state of the qubit can be indirectly inferred by detecting small changes in the resonant frequency of the microwave cavity (caused by the state of the qubit). Superconducting quantum chips must be operated on low-temperature platforms such as dilution refrigerators to maintain the chip operating temperature far below the critical temperature.

[0067] (4) Superconducting quantum computers

[0068] A superconducting quantum computer is a computing device that uses the quantum properties of superconducting materials to implement quantum bits (Qubits) and perform quantum computing. Superconducting quantum computing uses superconducting Josephson junctions as basic building blocks to construct qubits. The state of the qubit is controlled by microwave pulses, which precisely adjust the energy state of the qubit to implement quantum gate operations. The reading of qubits is usually achieved by measuring the energy state of the qubit, usually by coupling the qubit with a resonant cavity and indirectly by measuring the microwave signal of the resonant cavity. Superconducting quantum computing systems must operate at extremely low temperatures, usually in the millikelvin (mK) range, to reduce thermal noise and extend the coherence time of the qubit.

[0069] (5) Dilution refrigerator

[0070] A dilution refrigerator is a cryogenic device that is mainly used to produce an extremely low temperature environment close to absolute zero (0K, approximately equal to -273.15°C). It is a key tool for achieving ultra-low temperatures. The working principle of a dilution refrigerator is based on dilution refrigeration technology, which uses the dilution process of a dilution refrigerant (usually helium-3 (^3He)) in superfluid helium-4 (^4He) to achieve extremely low temperatures.

[0071] In superconducting quantum computing or quantum communication systems, superconducting quantum chips are tightly integrated with circulators. The readout signal of the quantum bit is transmitted unidirectionally through the circulator to the subsequent signal amplification and processing link (such as superconducting quantum bit parametric amplifier, classical amplifier or demodulator, etc.), without being fed back to the quantum bit to affect the stability of its quantum state. Specifically, the circulator provides a controlled signal path for the superconducting quantum chip, ensuring that the readout signal flows along the predetermined path, avoiding unnecessary cross-interference, and helping to build a high-fidelity, low-noise quantum information processing system.

[0072] As can be seen from the above, both superconducting quantum chips and superconducting Josephson parametric amplifiers require circulators to isolate signals, thereby improving signal transmission quality and reducing interference between signals. However, as the number of superconducting quantum bits increases, the superconducting quantum bit measurement and control system becomes very large, the use of various isolators and circulators increases, and the cost increases massively. Reducing the cost of major components such as isolators and circulators is currently an important goal of superconducting quantum computer research and development.

[0073] At present, microwave circulators are mainly based on the Faraday rotation effect, in which the polarization plane rotates when electromagnetic waves are transmitted in gyromagnetic ferrite materials (with an external DC magnetic field), to achieve unidirectional signal transmission. Specifically, under the combined action of the microwave field and the constant magnetic field generated by the DC line, the ferrite material produces gyromagnetic properties and performs polarization rotation on the electromagnetic waves propagating therein, and can strongly absorb the electromagnetic waves (ferromagnetic resonance). After proper design, the polarization plane of the electromagnetic wave is perpendicular to the grounded resistive plug during forward transmission, so the attenuation is very small. During reverse transmission, the polarization plane of the electromagnetic wave is parallel to the grounded resistive plug and is almost completely absorbed. This gyromagnetic phenomenon can be used to produce devices such as Figure 2 Circulator shown.

[0074] For example, Figure 2 As shown, the microwave signal input from port 1 flows to port 2, the microwave signal input from port 2 flows to port 3, and the microwave signal input from port 3 flows to port 1. That is, when a microwave signal is input from any port, it can only be output from the next port in a specific order and cannot be transmitted in the reverse direction.

[0075] However, superconducting quantum chips are extremely sensitive to magnetic fields, which can degrade the performance of superconducting quantum bits. Currently, circulators on superconducting quantum computers are all made of magnetic materials, so very special casings need to be designed to prevent magnetic field leakage from affecting superconducting quantum chips, which makes circulators expensive.

[0076] In view of this, the present invention provides a circulator, which is prepared based on the non-reciprocal effect (which enables unidirectional transmission of microwave signals) produced by the photomechanical interaction between two superconducting cavities assisted by sound waves. There is no need to increase the magnetic field, which can greatly reduce the production cost of the circulator and reduce the heat generation of the circulator.

[0077] The circulator provided by the present invention is described in detail below with reference to the accompanying drawings.

[0078] like Figure 3 As shown, the circulator 300 provided by the present invention includes a plurality of superconducting cavities and at least one acoustic wave device, wherein the superconducting cavity is a microwave resonant cavity made of superconducting materials (such as niobium, aluminum, niobium nitride, etc.).

[0079] Specifically, Figure 3 Three superconducting cavities 311 and three acoustic wave devices 321 are taken as an example, but not limited thereto. For example, the circulator 300 may include two superconducting cavities and one acoustic wave device, or the circulator 300 may include four superconducting cavities and four acoustic wave devices. When the number of the multiple superconducting cavities is 2, the circulator is called an isolator.

[0080] It should be understood that a microwave resonant cavity is a closed or semi-closed structure used to generate, amplify and measure electromagnetic waves in the microwave frequency range (e.g., 300 MHz to 300 GHz). The microwave resonant cavity is designed with a specific geometric shape and size so that the electromagnetic wave forms a standing wave in the cavity, thereby achieving selective response and amplification of signals of a specific frequency (e.g., microwave signals of 4 GHz to 8 GHz). The present invention does not limit the type of microwave resonant cavity. For example, the microwave resonant cavity can be a rectangular resonant cavity, a cylindrical resonant cavity, a coaxial resonant cavity, or a waveguide resonant cavity.

[0081] Among them, the first acoustic wave device is used to generate acoustic waves, and the acoustic waves are transmitted between the first superconducting cavity and the second superconducting cavity along a preset direction. The first superconducting cavity and the second superconducting cavity are coupled by optical force interaction through acoustic waves to produce non-reciprocity, so that the signal between the first superconducting cavity and the second superconducting cavity is transmitted along the target transmission direction (i.e., a specific direction).

[0082] Specifically, the first superconducting cavity and the second superconducting cavity are any two of the plurality of superconducting cavities 311. For example, the first superconducting cavity may be Figure 3 From the first superconducting cavity in the top-to-bottom direction, the second superconducting cavity can be Figure 3The second superconducting cavity in the direction from top to bottom; the first superconducting cavity can also be Figure 3 The second superconducting cavity in the direction from top to bottom can be Figure 3 The third superconducting cavity from top to bottom. In addition, it should be noted that the first superconducting cavity and the second superconducting cavity are directly coupled to each other through capacitance and inductance.

[0083] The first acoustic wave device is one of the at least one acoustic wave device 321, and is located near the first superconducting cavity and the second superconducting cavity, for example, Figure 3 As shown, in the first superconducting cavity Figure 3 From top to bottom, the first superconducting cavity and the second superconducting cavity are Figure 3 In the case of the second superconducting cavity from top to bottom, the first acoustic wave device can be Figure 3 The first acoustic wave device from left to right; in the first superconducting cavity is Figure 3 The second superconducting cavity from top to bottom is Figure 3 In the case of the third superconducting cavity in the top-to-bottom direction, the first acoustic wave device can be Figure 3 The second acoustic wave device from left to right. The preset direction is a preset direction that can be configured by the staff, for example, Figure 3 For example, the preset direction may be the direction of arrow S, or the preset direction may be a vertical direction. The signal may be a microwave signal, and the microwave signal is taken as an example for description below.

[0084] That is to say, an acoustic wave device is added between any two superconducting cavities, so that any two superconducting cavities can be coupled by acoustic waves. When the acoustic wave device generates acoustic waves, the acoustic waves are transmitted along a preset direction, thereby coupling the two superconducting cavities through the acoustic waves, generating a non-reciprocal effect, and realizing unidirectional transmission of microwave signals.

[0085] It should be noted that the non-reciprocal effect based on quantum optical systems - unidirectional transmission of photons has been realized in the laboratory. That is, theoretical and experimental studies have shown that the nonlinear interaction caused by the coupling of two optical modes with acoustic wave modes in optomechanical systems can produce non-reciprocal phenomena, enabling unidirectional transmission of optical signals.

[0086] The circulator provided by the present invention generates non-reciprocity based on the interaction between acoustic waves and two superconducting cavities through optomechanics, so that signals can be transmitted unidirectionally in the two superconducting cavities without increasing the magnetic field. That is, the circulator provided by the present invention does not contain a magnetic field, which can greatly reduce the production cost of the circulator, and thus reduce the research and development cost of superconducting quantum computers.

[0087] Furthermore, in order to reduce the sound wave transmission loss and improve the sound wave transmission efficiency, such as Figure 3As shown, the circulator 300 also includes an acoustic wave medium layer 330. The first superconducting cavity and the second superconducting cavity are connected through the acoustic wave medium layer 330 in a preset direction. The first acoustic wave device is arranged on the acoustic wave medium layer 330. The acoustic wave is transmitted along the acoustic wave medium layer 330 to limit the transmission of the acoustic wave in the preset direction.

[0088] Specifically, the acoustic wave medium layer 330 refers to a deformable material layer, and the deformable material layer refers to a film or thin layer structure made of a material that is easy to change shape or size under the action of external force.

[0089] Exemplarily, the material of the acoustic wave medium layer 330 may be zinc oxide (ZnO) or quartz, etc. The acoustic wave medium layer 330 may utilize its own physical properties (such as piezoelectric effect, nanostructure properties, etc.) to exhibit deformation response.

[0090] It should be understood that zinc oxide is a semiconductor material with high hardness and good mechanical stability. At the nanoscale, zinc oxide nanowires, nanofilms or nanoparticles can show high strain sensitivity and certain plasticity. Quartz crystal is a material with high hardness and excellent thermal stability. Under certain conditions, quartz crystal can respond to external forces due to its piezoelectric effect, that is, it can produce mechanical deformation under the action of an electric field, or generate electric charge under the action of mechanical stress. This conversion between strain and charge can be regarded as the deformation of quartz in specific functional applications.

[0091] It should be noted that, since the transmission efficiency of the acoustic wave along the acoustic wave medium layer 330 is relatively high, the weak influence of the acoustic wave on other superconducting cavities can be ignored.

[0092] Exemplarily, the critical temperature of the superconducting material in the present invention is greater than or equal to the liquid nitrogen temperature, that is, the superconducting material in the present invention is a high-temperature superconducting material, and the superconducting cavity is a microwave resonant cavity made of the high-temperature superconducting material.

[0093] Specifically, high-temperature superconducting materials refer to superconducting materials whose critical temperature works at liquid nitrogen temperature (77K). For example, the superconducting material can be bismuth strontium calcium copper oxide superconductor (BSCCO) with a critical temperature of 110K, thallium barium calcium copper oxide superconductor (TBCCO) with a critical temperature of 125K, or mercury barium calcium copper oxide superconductor (HBCCO) with a critical temperature of 135K.

[0094] In this embodiment, a superconducting cavity is prepared by high-temperature superconducting materials, so that the superconducting cavity can work normally at high temperature, and the circulator can be placed in the 4K temperature zone of the dilution refrigerator, reducing the circulator's occupation of the 10mK low-temperature zone of the dilution refrigerator and improving the flexibility of the circulator placement position.

[0095] The present invention does not limit the specific structure of the superconducting cavity. For example, Figure 3As shown, the superconducting cavity may be a coplanar waveguide resonant cavity made of superconducting material, and the coplanar waveguide resonant cavity includes a cavity body 3111 , a central conductor 3112 , an input feeder port 3113 , and an output feeder port 3114 .

[0096] Specifically, the cavity 3111 has a containing space 3111a, and the central conductor 3112 is located in the containing space 3111a, which is used to transmit signals, and the signals are reflected back and forth at both ends of the field rectangle to form standing waves. The frequency of the signal can be determined according to the length of the central conductor, that is, the frequency of the signal can be adjusted by adjusting the length of the central conductor, for example, the signal can be adjusted to a microwave signal.

[0097] The input feeder port 3113 and the output feeder port 3114 are respectively located at two ends of the central conductor 3112, and there is a gap between the central conductor 3112 and the input feeder port 3113, and there is a gap between the central conductor 3112 and the output feeder port 3114. The input feeder port 3113 inputs the microwave signal into the central conductor 3112 through capacitive coupling, and the output feeder port 3114 outputs the microwave signal on the central conductor 3112 through capacitive coupling.

[0098] The central conductor 3112, the input feeder port 3113 and the output feeder port 3114 of the coplanar waveguide resonant cavity are on the same substrate plane, and have the advantages of compact structure, low loss and flexible resonance mode.

[0099] The present invention does not limit the type of acoustic wave device, as long as it can generate acoustic waves. Exemplarily, the acoustic wave device can be a surface acoustic wave device.

[0100] Specifically, surface acoustic wave (SAW) devices are electronic components designed and manufactured using the surface acoustic wave phenomenon, and mainly use the characteristics of acoustic waves propagating on the surface of solid media to achieve signal processing and sensing functions. The surface acoustic wave phenomenon refers to a type of elastic wave that propagates along the surface of a solid medium. The energy of this wave is mainly concentrated near the surface of the medium, and the energy decays rapidly as it penetrates deeper into the medium.

[0101] The core of the surface acoustic wave device is the interdigital transducer, which is usually composed of metal electrodes (such as aluminum) forming an interlaced finger structure on a piezoelectric substrate (such as quartz, lithium tantalum oxide LiTaO3, lithium niobium oxide LiNbO3, etc.). When an electrical signal is applied to the interdigital transducer, the piezoelectric effect causes acoustic waves to be generated on the surface of the substrate; conversely, when the acoustic wave reaches the interdigital transducer, it is converted back into an electrical signal.

[0102] For example, Figure 3 As shown, the first acoustic wave device includes an acoustic wave transmitter 3211 and an acoustic wave reflector 3212 .

[0103] Specifically, the sound wave emitter 3211 is located at one end of the sound wave medium layer 330 close to the first superconducting cavity in a preset direction, or it can be said that the sound wave emitter 3211 is located at one end of the sound wave medium layer 330 close to the first superconducting cavity, and is used to generate sound waves. The sound wave reflector 3212 is located at one end of the sound wave medium layer 330 close to the second superconducting cavity in a preset direction, or it can be said that the sound wave reflector 3212 is located at one end of the sound wave medium layer 330 close to the second superconducting cavity, and is used to adjust the transmission direction of the sound wave to enhance the sound wave on the piezoelectric layer.

[0104] Specifically, the target transmission direction of the microwave signal can be determined based on the signal matrix of the center frequencies of the first superconducting cavity and the second superconducting cavity, and the center frequencies of the superconducting cavities are the same, that is, the center frequencies of the first superconducting cavity and the second superconducting cavity are the same. Signal transmission matrix It can be expressed by the following formula (1):

[0105]

[0106] Among them, the signal transmission matrix It is used to indicate the probability of microwave signal transmission in each transmission direction. represents the probability of transmission in the transmission direction between the two ports of the first superconducting cavity, represents the probability of transmission in the transmission direction from the first superconducting cavity to the second superconducting cavity, represents the probability of transmission in the transmission direction from the second superconducting cavity to the first superconducting cavity, It represents the probability of transmission in the transmission direction between the two ports of the second superconducting cavity, and the target transmission direction is the transmission direction corresponding to the maximum probability in the signal transmission matrix.

[0107] Furthermore, the signal transmission matrix can be determined based on the coupling phase between the first superconducting cavity and the first acoustic wave device and the coupling phase between the second superconducting cavity and the first acoustic wave device. That is, the present invention can change the unidirectional transmission direction between any two superconducting cavities by adjusting the coupling phase.

[0108] The relationship between the coupling phase between the first superconducting cavity and the first acoustic wave device, the coupling phase between the second superconducting cavity and the first acoustic wave device, and the signal transmission matrix is ​​described below.

[0109] Specifically, the two superconducting cavities are coupled with the acoustic wave, and the Hamiltonian of the two superconducting cavities (i.e., the first superconducting cavity and the second superconducting cavity) is expressed by the following formula (2):

[0110]

[0111] in, represents the Hamiltonian, represents the frequency of photons in the first superconducting cavity, represents the photon generation operator in the first superconducting cavity, represents the photon annihilation operator in the first superconducting cavity, is Planck's constant, represents the frequency of photons in the second superconducting cavity, represents the photon generation operator in the second superconducting cavity, represents the photon annihilation operator in the second superconducting cavity, represents the frequency of the phonon of the first acoustic wave device, represents the generation operator of phonons and photons in the first acoustic wave device, represents the annihilation operator of phonons and photons in the first acoustic wave device, represents the coupling strength between the first superconducting cavity and the second superconducting cavity, represents the optical force coupling intensity between the first acoustic wave device and the first superconducting cavity, represents a natural constant, represents an imaginary root, represents the coupling phase between the first superconducting cavity and the first acoustic wave device, represents the optical-mechanical coupling strength between the first acoustic wave device and the second superconducting cavity, represents the coupling phase between the second superconducting cavity and the first acoustic wave device. situation and situations, corresponding to different unidirectional transmission directions.

[0112] The frequency of the superconducting cavity is The Hamiltonian shown in formula (2) can be expressed by the following formula (3) when the analytical calculation is performed in the rotating coordinate system:

[0113]

[0114] in, represents the frequency detuning between the first superconducting cavity and the first acoustic wave device, , the frequencies of the transmission channels at each port of the circulator are very close, so we assume that the frequencies of the superconducting cavities are the same , and its decay rate is also the same, that is, The attenuation rate of the sound wave is simplified to .

[0115] When the amplitude of the average light wave in the cavity is much larger than its fluctuation, we make a linear approximation of the light field, that is, and , represents the amplitude of the microwave signal in the first superconducting cavity, represents the amplitude of the microwave signal in the second superconducting cavity, represents an infinitesimal quantity. Here I assume that its average amplitude is a real number, then as well as ,in, is the number of photons in the first superconducting cavity, It refers to the number of photons in the second superconducting cavity.

[0116] By linearization approximation, the Hamiltonian shown in formula (3) can be expressed by the following formula (4):

[0117]

[0118] The coupling strength between each superconducting cavity and the acoustic wave is similar, and the average number of photons is also similar, so we assume that Ignoring the second-order small quantity and performing differentiation on the above formula (4), we can obtain the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity (the microwave amplitude in the superconducting cavity minus the stable value), the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity, and the motion equation of the sound wave.

[0119] Specifically, the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity, the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity, and the motion equation of the acoustic wave are respectively expressed by the following formulas (5), (6), and (7):

[0120]

[0121] in, d represents the differential operator, t represents the transmission time of the microwave signal, represents the effective coupling strength between the first superconducting cavity and the first acoustic wave device when the average number of multi-photons or photons in the first superconducting cavity is not 1, represents the attenuation rate of the first acoustic wave device.

[0122] Furthermore, the acoustic wave device is designed as a high-loss device, and the attenuation rate is much greater than the attenuation of superconducting cavity photons, that is, , using the adiabatic approximation, we can get and , It can be expressed by the following formula (8): It can be expressed by the following formula (9).

[0123]

[0124] Will Substitute into the above formulas (5) and (6), and for convenience, define , the above formulas (5) and (6) can be expressed as formulas (10) and (11), where: No actual physical meaning.

[0125]

[0126] After determining the coupling phase between the first superconducting cavity and the first acoustic wave device, the coupling phase between the second superconducting cavity and the first acoustic wave device, the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity, and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity, the coupling phase between the first superconducting cavity and the first acoustic wave device and the coupling phase between the second superconducting cavity and the first acoustic wave device are substituted into formula (10) and formula (11), and after certain conversion processing, the signal transmission matrix can be obtained.

[0127] That is to say, the signal transmission matrix is ​​determined based on the coupling phase between the first superconducting cavity and the first acoustic wave device and the coupling phase between the second superconducting cavity and the first acoustic wave device, through the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity.

[0128] For example, if , , then the signal transmission matrix can be shown as formula (12):

[0129]

[0130] Specifically, it can be seen from formula (12) that and In the case of , that is, the probability of microwave signal transmission from the first superconducting cavity to the second superconducting cavity is basically 0, , indicating that the transmission of microwave signals from the second superconducting cavity to the first superconducting cavity is not zero. hour, , indicating that the target transmission direction is from the second superconducting cavity to the first superconducting cavity, and the microwave signal can be transmitted almost without loss.

[0131] For example, and It can be determined based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, and the attenuation rates of multiple superconducting cavities are the same. That is, the target transmission direction is not only related to the coupling phase, but also to the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity. When preparing the circulator, the present invention can also adjust the target transmission direction by adjusting the attenuation rate of the first acoustic wave device and / or the attenuation rate of the first superconducting cavity.

[0132] Specifically, It can be determined based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity through a first corresponding relationship, It can be determined based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity through a second corresponding relationship. The first corresponding relationship is used to characterize The corresponding relationship between the frequency of the microwave signal, the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity is used to characterize The corresponding relationship between the frequency of the microwave signal, the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity.

[0133] The first corresponding relationship and the second corresponding relationship are described in detail below.

[0134] For example, in consideration of the influence of noise (such as noise of the superconducting cavity and noise of sound waves), the above formula (10) and formula (11) can be expressed as formula (13) and formula (14), respectively:

[0135]

[0136] in, represents the coupling strength with external environmental noise, represents the input noise of the first superconducting cavity, represents the input noise of the first acoustic wave device, represents the input noise of the second superconducting cavity, It has no actual physical meaning and can be adjusted Get, for example, .

[0137] Specifically, the first corresponding relationship can be determined based on the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise (i.e., the above formula (13)) and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity (i.e., the above formula (14)), and the second corresponding relationship can also be determined based on the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity.

[0138] For example, in , , , adjust the parameters so that In the case of, based on the above formula (13) and formula (14), the first corresponding relationship can be shown as the following formula (15), and the second corresponding relationship can be shown as the following formula (16):

[0139]

[0140] in, represents the frequency of the microwave signal, represents the attenuation rate of the first acoustic wave device, represents the decay rate of the superconducting cavity.

[0141] In order to meet the needs of superconducting quantum bit reading signal transmission on the superconducting quantum chip, the frequency of the superconducting cavity is set to 6 GHz, the frequency of the acoustic wave device is set to 0.2 GHz, and the coupling strength between the acoustic wave device and the superconducting cavity is set to 1 MHz. In this case, based on the above formulas (15) and (16), and With the frequency of the signal The changes in Figure 4 and Figure 5 shown.

[0142] Specifically, from Figure 4 It can be seen that the probability of signal transmission from the first superconducting cavity to the second superconducting cavity is very low, especially near the center frequency of the superconducting cavity, the probability (which can also be the ratio of the transmission amplitude of the output microwave signal to the transmission amplitude of the input microwave signal) is close to 0. Figure 5 It can be seen that the probability of microwave signals being transmitted from the second superconducting cavity to the first superconducting cavity is relatively high, especially near the center frequency of the superconducting cavity, where the probability is close to 1, that is, the input microwave signal of the second superconducting cavity is almost completely output from the first superconducting cavity.

[0143] While keeping the above parameters unchanged (i.e. the frequency of the superconducting cavity is still 6 GHz, the frequency of the acoustic wave device is still 0.2 GHz, and the coupling strength between the acoustic wave device and the superconducting cavity is still 1 MHz), the attenuation of the superconducting cavity is adjusted to MHz, based on the above formula (15) and formula (16), and The frequency of the microwave signal The changes in Figure 6 and Figure 7 shown.

[0144] Specifically, from Figure 7 It can be seen that The peak of the transmission curve near the center frequency becomes narrower, which means that when transmitting signals from the second superconducting cavity to the first superconducting cavity, the bandwidth of the signal that can be transmitted efficiently becomes narrower. Figure 6 It can be seen that The frequency range where the signal transmission probability on the curve is close to 0 also becomes narrower. In other words, the transmission bandwidth of the microwave signal is related to the attenuation rate of the superconducting cavity. The transmission bandwidth of the microwave signal can be adjusted by adjusting the attenuation rate of the superconducting cavity.

[0145] While keeping the above parameters unchanged (i.e. the frequency of the superconducting cavity is still 6 GHz, the frequency of the acoustic wave device is still 0.2 GHz, and the coupling strength between the acoustic wave device and the superconducting cavity is still 1 MHz), the attenuation rate of the acoustic wave is adjusted to MHz, based on the above formula (15) and formula (16), and The frequency of the microwave signal The changes in Figure 8 and Fig. 9 shown.

[0146] Specifically, from Figure 8 It can be seen that The highest value on the curve is depressed by an order of magnitude, so increasing the attenuation rate of the surface acoustic wave can further suppress the transmission of the signal from the first superconducting cavity to the second superconducting cavity. Fig. 9 It can be seen that The curve changes very little, indicating that the attenuation rate of the surface acoustic wave signal has little effect on the signal transmission from the second superconducting cavity to the first superconducting cavity. In other words, by increasing the attenuation rate of the surface acoustic wave, the probability of signal transmission from the second superconducting cavity to the first superconducting cavity can be increased.

[0147] Exemplarily, the absolute value of the difference between the center frequency of the superconducting cavity and the frequency of the signal is less than a preset value (e.g., 0.1 GHz), that is, the center frequency of the superconducting cavity in the circulator is controlled near the frequency of the transmission signal, or the frequency of the transmission signal is controlled near the center frequency of the superconducting cavity.

[0148] Specifically, when the acoustic wave device is excited, the acoustic wave is transmitted between the first superconducting cavity and the second superconducting cavity through the piezoelectric material, causing the two superconducting cavities to deform, thereby changing the width of the intermediate conductor and the gap of the superconducting cavity, thereby affecting the resonant frequency (i.e., the center frequency) of the superconducting cavity.

[0149] In this embodiment, the frequency of the transmission signal is brought close to the center frequency of the superconducting cavity, which can reduce the loss and attenuation of the transmission signal and allow the transmission signal to remain in the superconducting cavity for a long time.

[0150] An embodiment of the present invention further provides a quantum computer having a circulator as shown in any of the above embodiments, wherein the circulator is connected to a superconducting quantum chip or a superconducting Josephson parametric amplifier to isolate signals in different transmission directions.

[0151] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0152] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0153] In the description of this specification, the description with reference to the terms "this embodiment", "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0154] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0155] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the present invention.

Claims

1. A circulator, characterized in that: The circulator includes a plurality of superconducting cavities, at least one acoustic wave device and an acoustic wave dielectric layer, wherein the superconducting cavity is a microwave resonant cavity prepared by superconducting material, and the first acoustic wave device includes an acoustic wave transmitter and an acoustic wave reflector; The acoustic wave medium layer is arranged along a preset direction, a partial area of ​​the first superconducting cavity and a partial area of ​​the second superconducting cavity are arranged on the acoustic wave medium layer, the acoustic wave transmitter is located at one end of the acoustic wave medium layer close to the first superconducting cavity, the acoustic wave reflector is located at one end of the acoustic wave medium layer close to the second superconducting cavity, and a partial area of ​​the first superconducting cavity and a partial area of ​​the second superconducting cavity are located between the acoustic wave transmitter and the acoustic wave reflector, the acoustic wave transmitter is used to generate an acoustic wave, and the acoustic wave reflector is used to adjust the transmission direction of the acoustic wave so that the acoustic wave is transmitted along the preset direction between the first superconducting cavity and the second superconducting cavity. The first superconducting cavity and the second superconducting cavity perform optical force interaction through the acoustic wave, so that the signal between the first superconducting cavity and the second superconducting cavity is transmitted along a target transmission direction, wherein the first superconducting cavity and the second superconducting cavity are any two of the multiple superconducting cavities, the first acoustic wave device is one of the at least one acoustic wave device, and the target transmission direction is adjusted based on the coupling phase between the first superconducting cavity and the first acoustic wave device, the coupling phase between the second superconducting cavity and the first acoustic wave device, the attenuation rate of the first acoustic wave device and / or the attenuation rate of the first superconducting cavity.

2. The circulator according to claim 1, characterized in that: The target transmission direction is determined based on a signal transmission matrix of the center frequencies of the first superconducting cavity and the second superconducting cavity, wherein the center frequencies of the superconducting cavities are the same and the signal transmission matrix , the signal transmission matrix is ​​used to represent the probability of the signal being transmitted in each transmission direction, represents the probability of transmission in the transmission direction between the two ports of the first superconducting cavity, represents the probability of transmission in the transmission direction from the first superconducting cavity to the second superconducting cavity, represents the probability of transmission in the transmission direction from the second superconducting cavity to the first superconducting cavity, represents the probability of transmission in the transmission direction between the two ports of the second superconducting cavity, and the target transmission direction is the transmission direction corresponding to the maximum probability in the signal transmission matrix.

3. The circulator according to claim 2, characterized in that: The signal transmission matrix is ​​determined based on a coupling phase between the first superconducting cavity and the first acoustic wave device and a coupling phase between the second superconducting cavity and the first acoustic wave device.

4. The circulator according to claim 3, characterized in that: The signal transmission matrix is ​​determined based on the coupling phase between the first superconducting cavity and the first acoustic wave device and the coupling phase between the second superconducting cavity and the first acoustic wave device, through the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity.

5. The circulator according to claim 4, characterized in that: The motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity is expressed by the following formula: The motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity is expressed by the following formula: in, d represents the differential operator, t represents the transmission time of the signal, represents an infinitesimal quantity, represents the photon annihilation operator in the first superconducting cavity, represents the decay rate of the superconducting cavity, represents a natural constant, represents an imaginary root, represents the coupling phase between the first superconducting cavity and the first acoustic wave device, represents the coupling phase between the second superconducting cavity and the first acoustic wave device, represents the coupling strength between the first superconducting cavity and the second superconducting cavity, represents the photon annihilation operator in the second superconducting cavity, , represents the effective coupling strength between the first superconducting cavity and the first acoustic wave device when the average number of multiphotons or photons in the first superconducting cavity is not 1, represents the attenuation rate of the first acoustic wave device, represents the frequency detuning between the first superconducting cavity and the first acoustic wave device, , represents the frequency of photons in the first superconducting cavity, represents the frequency of the phonon of the first acoustic wave device, Greater than .

6. The circulator according to claim 5, characterized in that: The motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity are determined by Hamiltonian.

7. The circulator according to claim 6, characterized in that The Hamiltonian is expressed by the following formula: in, represents the Hamiltonian, is Planck's constant, represents the generation operator of phonons and photons in the first acoustic wave device, represents the annihilation operator of phonons and photons in the first acoustic wave device, represents the amplitude of the signal in the first superconducting cavity, represents the amplitude of the signal in the second superconducting cavity, represents the photon generation operator in the first superconducting cavity, represents the photon generation operator in the second superconducting cavity, represents the optical force coupling strength between the first acoustic wave device and the first superconducting cavity, represents the optical force coupling strength between the first acoustic wave device and the second superconducting cavity.

8. The circulator according to claim 2, characterized in that: Said and stated The attenuation rate is determined based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, wherein the attenuation rates of the plurality of superconducting cavities are the same.

9. The circulator according to claim 8, characterized in that Said Based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, the attenuation rate of the first superconducting cavity is determined by a first corresponding relationship. Based on the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, the second corresponding relationship is determined, wherein the first corresponding relationship is used to characterize The corresponding relationship between the frequency of the signal, the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity, the second corresponding relationship is used to characterize The correspondence between the frequency of the signal, the attenuation rate of the first acoustic wave device and the attenuation rate of the first superconducting cavity.

10. The circulator according to claim 9, characterized in that The first corresponding relationship is expressed by the following formula: The second corresponding relationship is expressed by the following formula: in, represents the frequency of the signal, represents the attenuation rate of the first acoustic wave device, represents the decay rate of the superconducting cavity.

11. The circulator according to claim 9, characterized in that The transmission bandwidth of the signal is determined based on the decay rate of the superconducting cavity.

12. The circulator according to claim 9, characterized in that The first corresponding relationship is determined based on the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity, and the second corresponding relationship is determined based on the motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise and the motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity.

13. The circulator according to claim 12, characterized in that The motion equation of the microwave photon amplitude fluctuation term in the first superconducting cavity under the influence of noise is expressed by the following formula: The motion equation of the microwave photon amplitude fluctuation term in the second superconducting cavity under the influence of noise is expressed by the following formula: in, represents the differential operator, represents the transmission time of the signal, represents an infinitesimal quantity, represents the photon annihilation operator in the first superconducting cavity, represents the decay rate of the superconducting cavity, represents a natural constant, represents an imaginary root, represents the coupling phase between the first superconducting cavity and the first acoustic wave device, represents the coupling phase between the second superconducting cavity and the first acoustic wave device, represents the coupling strength between the first superconducting cavity and the second superconducting cavity, represents the photon annihilation operator in the second superconducting cavity, represents the coupling strength with external environmental noise, represents the input noise of the first superconducting cavity, represents the input noise of the first acoustic wave device, , represents the attenuation rate of the first acoustic wave device, Greater than , , , represents the input noise of the second superconducting cavity.

14. The circulator according to claim 1, characterized in that An absolute value of a difference between a center frequency of the superconducting cavity and a frequency of the signal is smaller than a preset value.

15. The circulator according to claim 1, characterized in that The number of the superconducting cavities is greater than or equal to 3, and the number of the acoustic wave devices is greater than or equal to 3.

16. The circulator according to claim 1, characterized in that The number of the superconducting cavities is 2, and the number of the acoustic wave devices is 1.

17. The circulator according to claim 1, characterized in that The microwave resonant cavity is a coplanar waveguide resonant cavity, and the coplanar waveguide resonant cavity comprises a cavity body, a central conductor, an input feeder port and an output feeder port; The cavity has a containing space; The central conductor is located in the accommodation space and is used to transmit signals; The input feeder port and the output feeder port are respectively located at two ends of the central conductor, with a gap between the central conductor and the input feeder port, and a gap between the central conductor and the output feeder port. The input feeder port is used to input a signal into the central conductor, and the output feeder port is used to output the signal on the central conductor.

18. A quantum computer, characterized in that: The circulator comprises the circulator as claimed in any one of claims 1 to 17, wherein the circulator is connected to a superconducting quantum chip or a superconducting Josephson parametric amplifier for isolating signals in different transmission directions.

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