Method for determining the fidelity of qubit quantum gates in a quantum processor and storage medium

Abstract

The present application discloses a method for determining the fidelity of a two-qubit quantum gate in a quantum processor and a storage medium. Among them, the method includes: determining an environmental qubit quantum gate associated with the two-qubit quantum gate in the quantum processor, where the two-qubit quantum gate and the environmental qubit quantum gate interact with each other in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate. The present application solves the technical problem of being unable to determine the fidelity of two qubit quantum gates.

Description

Technical Field

[0001] The present application relates to the field of superconducting quantum, and in particular, to a method for determining the fidelity of a qubit quantum gate in a quantum processor and a storage medium. Background Art

[0002] In the design process of a quantum chip, usually only the fidelity of an isolated two-qubit quantum gate is considered. However, in the actual use process of a quantum chip, two-qubit quantum gates will inevitably interact with surrounding qubits. But currently, there is no related technology to characterize the fidelity of two-qubit quantum gates in a multi-qubit environment, thus there is a technical problem that the fidelity of two-qubit quantum gates cannot be determined.

[0003] In view of the above problems, no effective solution has been proposed yet. Summary of the Invention

[0004] Embodiments of the present application provide a method for determining the fidelity of a qubit quantum gate in a quantum processor and a storage medium, so as to at least solve the technical problem that the fidelity of two qubit quantum gates cannot be determined.

[0005] According to one aspect of the embodiments of the present application, a method for the fidelity of a qubit quantum gate in a quantum processor is provided. The method may include: determining an environmental qubit quantum gate associated with a two-qubit quantum gate in the quantum processor, wherein the two-qubit quantum gate and the environmental qubit quantum gate interact with each other in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate.

[0006] According to another aspect of the embodiments of the present application, another method for the fidelity of a qubit quantum gate in a quantum processor is provided. The method may include: obtaining an environmental qubit quantum gate associated with a two-qubit quantum gate in the quantum processor by calling a first interface, wherein the first interface includes a first parameter, and the parameter value of the first parameter is the two-qubit quantum gate and the environmental qubit quantum gate, and the two-qubit quantum gate and the environmental qubit quantum gate interact with each other in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate; outputting the fidelity of the two-qubit quantum gate by calling a second interface, wherein the second interface includes a second parameter, and the parameter value of the second parameter is the fidelity of the two-qubit quantum gate.

[0007] According to another aspect of the embodiments of the present application, another method for the fidelity of qubit quantum gates in a quantum processor is provided. The method may include: obtaining, from a quantum platform, an environmental qubit quantum gate associated with a two-qubit quantum gate in the quantum processor, where the two-qubit quantum gate and the environmental qubit quantum gate interact with each other in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate; and returning the fidelity of the two-qubit quantum gate to the quantum platform.

[0008] According to one aspect of the embodiments of the present application, an apparatus for the fidelity of qubit quantum gates in a quantum processor is provided. The apparatus may include: a first determination unit, configured to determine an environmental qubit quantum gate associated with a two-qubit quantum gate in the quantum processor, where the two-qubit quantum gate and the environmental qubit quantum gate interact with each other in the quantum processor; a second determination unit, configured to determine the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; a third determination unit, configured to determine the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; and a fourth determination unit, configured to determine the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate.

[0009] According to another aspect of the embodiments of the present application, another apparatus for the fidelity of qubit quantum gates in a quantum processor is provided. The apparatus may include: a first acquisition unit, configured to obtain, by invoking a first interface, an environmental qubit quantum gate associated with a two-qubit quantum gate in the quantum processor, where the first interface includes a first parameter, and the parameter value of the first parameter is the two-qubit quantum gate and the environmental qubit quantum gate, and the two-qubit quantum gate and the environmental qubit quantum gate interact with each other in the quantum processor; a fifth determination unit, configured to determine the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; a sixth determination unit, configured to determine the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; a seventh determination unit, configured to determine the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate; and an output unit, configured to output the fidelity of the two-qubit quantum gate by invoking a second interface, where the second interface includes a second parameter, and the parameter value of the second parameter is the fidelity of the two-qubit quantum gate.

[0010] According to another aspect of the embodiments of the present application, there is provided another apparatus for the fidelity of qubit quantum gates in a quantum processor. The apparatus may include: a second acquisition unit configured to acquire, from a quantum platform, environmental qubit quantum gates associated with two-qubit quantum gates in the quantum processor, where the two-qubit quantum gates interact with the environmental qubit quantum gates in the quantum processor; an eighth determination unit configured to determine the fidelity error of the environmental qubit quantum gates based on the fidelity error of the two-qubit quantum gates; a ninth determination unit configured to determine the frequency of the environmental qubit quantum gates based on the fidelity error of the environmental qubit quantum gates; a tenth determination unit configured to determine the fidelity of the two-qubit quantum gates based on the frequency of the environmental qubit quantum gates; and a return unit configured to return the fidelity of the two-qubit quantum gates to the quantum platform.

[0011] According to another aspect of the embodiments of the present application, there is also provided a computer-readable storage medium. The computer-readable storage medium includes a stored program, where, when the program runs, it controls the device where the storage medium is located to execute the method for determining the fidelity of qubit quantum gates in the quantum processor as described in any one of the above.

[0012] According to another aspect of the embodiments of the present application, there is also provided a processor. The processor is configured to run a program, where, when the program runs, it executes the method for determining the fidelity of qubit quantum gates in the quantum processor as described in any one of the above.

[0013] In the embodiments of the present application, environmental qubit quantum gates associated with two-qubit quantum gates in the quantum processor are determined, where the two-qubit quantum gates interact with the environmental qubit quantum gates in the quantum processor; the fidelity error of the environmental qubit quantum gates is determined based on the fidelity error of the two-qubit quantum gates; the frequency of the environmental qubit quantum gates is determined based on the fidelity error of the environmental qubit quantum gates; and the fidelity of the two-qubit quantum gates is determined based on the frequency of the environmental qubit quantum gates. That is to say, the embodiments of the present application consider the influence of the environmental qubit quantum gates associated with the two-qubit quantum gates in the quantum processor on the two-qubit quantum gates, redefine the fidelity, decompose the fidelity error of the two-qubit quantum gates onto different environmental qubit quantum gates, provide guidance for the frequency selection of the environmental qubit quantum gates, so as to determine the fidelity that meets the conditions, achieving the technical effect of improving the accuracy of determining the fidelity of the two-qubit quantum gates, and solving the technical problem of being unable to determine the fidelity of the two qubit quantum gates.

[0014] It can be easily noted that the above general description and the following detailed description are only for exemplifying and explaining the present application, and do not constitute a limitation to the present application. Description of the Drawings

[0015] The accompanying drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0016] Figure 1 is a hardware structure block diagram of a computer terminal (or mobile device) for implementing a method for determining the fidelity of a qubit quantum gate in a quantum processor according to an embodiment of the present application;

[0017] Figure 2 is a structure block diagram of a computing environment according to an embodiment of the present application;

[0018] Figure 3 is a structure block diagram of a service mesh according to an embodiment of the present application;

[0019] Figure 4 is a flowchart of a method for determining the fidelity of a qubit quantum gate in a quantum processor according to an embodiment of the present application;

[0020] Figure 5 is a flowchart of another method for determining the fidelity of a qubit quantum gate in a quantum processor according to an embodiment of the present application;

[0021] Figure 6 is a schematic diagram of the access of a computer device to a private network according to an embodiment of the present application;

[0022] Figure 7 is a flowchart of another method for determining the fidelity of a qubit quantum gate in a quantum processor according to an embodiment of the present application;

[0023] Figure 8 is a schematic diagram of the frequency selection of a qubit and a coupler according to an embodiment of the present application;

[0024] Figure 9 is a schematic diagram of the fidelity of a 15 - qubit model (15Q model) according to an embodiment of the present application;

[0025] Figure 10 is a schematic diagram of the result of expanding the maximum value according to an embodiment of the present application;

[0026] Figure 11(a) is a schematic diagram of an evolution result according to an embodiment of the present application;

[0027] Figure 11(b) is a schematic diagram of another evolution result according to an embodiment of the present application;

[0028] Figure 12(a) is a schematic diagram of another evolution result according to an embodiment of the present application;

[0029] Figure 12(b) is a schematic diagram of another evolution result according to an embodiment of the present application;

[0030] Figure 13 is a schematic diagram of the leaked information of an evolution result according to an embodiment of the present application;

[0031] Figure 14 is a schematic diagram of the difference of a phase modulation according to an embodiment of the present application;

[0032] Figure 15 is a schematic diagram of a method for determining the fidelity of a qubit quantum gate in a quantum chip according to an embodiment of the present application;

[0033] Figure 16 is a schematic diagram of another apparatus for determining the fidelity of a qubit quantum gate in a quantum chip according to an embodiment of the present application;

[0034] Figure 17 is a schematic diagram of another apparatus for determining the fidelity of a qubit quantum gate in a quantum chip according to an embodiment of the present application;

[0035] Figure 18 is a structural block diagram of a computer terminal according to an embodiment of the present application. Detailed implementation manners

[0036] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0037] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0038] First, some nouns or terms that appear in the process of describing the embodiments of the present application are applicable to the following explanations:

[0039] Fidelity can be used to characterize the similarity between the output and the input signal reproduced by an electronic device;

[0040] Coupler, a radio frequency device that can extract a small part of the signal from the wireless signal backbone channel;

[0041] State can also be called phase;

[0042] Basis vector, a proper noun in semiconductor physics, can be used to characterize the vector that determines the unit cell size;

[0043] Hamiltonian: can be the sum of the kinetic energies of all particles plus the potential energy of the particles related to the system;

[0044] Quantum bit (fluxonium), a type of inductive qubit (flux qubit) in superconducting qubits, also known as the first-level qubit under the flux qubit (quantum bit, abbreviated as Qubit). It can be used to connect many large junctions (large capacitors) in series and then connect the series of large junctions in parallel with small junctions. There is no small superconducting island in the whole loop to avoid the influence of charge drift. At the same time, the series connection of large junctions provides a large enough inductance so that the quantum fluctuations of the charge distribution are less than the charge of a Cooper pair. When the oscillation frequency of the system is much lower than the plasma oscillation frequency of the large junction, fluxonium can well suppress the low-frequency charge drift while retaining the high-frequency oscillation part of the charge. When the loop magnetic flux of fluxonium changes, its energy level structure can be adjusted within a large range (0.5 - 10 GHz);

[0045] Quantum bit (transmission line shunted plasma oscillation qubit, abbreviated as transmon qubit), a type of capacitive qubit (charge qubit) in superconducting qubits, also known as the first-level qubit under the charge qubit (copper-pairbox). It is used to increase the ratio between the Josephson energy (EJ) and the charge energy (EC) to flatten the dispersion relationship between the system energy state and the gate charge. It has a large capacitor connected in parallel at both ends of the Josephson junction to reduce the sensitivity to charge noise, and the coupling capacitor between it and a linear resonator makes it form a circuit quantum electrodynamics (circuit-QED) system with the linear resonator, enabling the manipulation and readout of the qubit.

[0046] Example 1

[0047] According to an embodiment of the present application, a method for determining the fidelity of qubit quantum gates in a quantum processor is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0048] The method embodiment provided in the first embodiment of the present application can be executed in a mobile terminal, a computer terminal, or a similar computing device. Figure 1 It is a hardware structure block diagram of a computer terminal (or mobile device) for implementing a method for determining the fidelity of qubit quantum gates in a quantum processor according to an embodiment of the present application. As Figure 1 shown, the computer terminal 10 (or mobile device) may include one or more (shown as 102a, 102b,..., 102n in the figure) processors 102 (the processor 102 may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA), a memory 104 for storing data, and a transmission module 106 for communication functions. In addition, it may further include: a display, an input / output interface (I / O interface), a Universal Serial Bus (USB) port (which can be included as one of the ports of the BUS bus), a network interface, a power supply, and / or a camera. Those of ordinary skill in the art can understand that Figure 1 the structure shown is only schematic and does not limit the structure of the above-mentioned electronic device. For example, the computer terminal 10 may further include more or fewer components than Figure 1 shown, or have a different configuration from Figure 1 shown.

[0049] It should be noted that the above one or more processors 102 and / or other voice separation circuits can generally be referred to as "voice separation circuits" in this article. The voice separation circuit can be embodied in whole or in part as software, hardware, firmware, or any arbitrary combination thereof. In addition, the voice separation circuit can be a single independent processing module, or be incorporated in whole or in part into any one of the other elements in the computer terminal 10 (or mobile device). As involved in the embodiments of the present application, the voice separation circuit is a kind of processor control (such as the selection of a variable resistance terminal path connected to an interface).

[0050] The memory 104 can be used to store software programs and modules of application software, such as the program instructions / data storage device corresponding to the method for determining the fidelity of qubit quantum gates in the quantum processor in the embodiments of the present application. The processor 102 executes various functional applications and data processing by running the software programs and modules stored in the memory 104, that is, implements the method for determining the fidelity of qubit quantum gates in the above-mentioned quantum processor. The memory 104 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memories. In some instances, the memory 104 may further include memories remotely provided with respect to the processor 102, and these remote memories can be connected to the computer terminal 10 through a network. Examples of the above-mentioned network include but are not limited to the Internet, enterprise intranet, local area network, mobile communication network, and combinations thereof.

[0051] The transmission device 106 is used to receive or send data via a network. Specific examples of the above-mentioned network may include the wireless network provided by the communication provider of the computer terminal 10. In one instance, the transmission device 106 includes a network adapter (Network Interface Controller, NIC), which can be connected to other network devices through a base station and thus communicate with the Internet. In one instance, the transmission device 106 can be a Radio Frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0052] The display can be, for example, a touch-screen Liquid Crystal Display (LCD), which enables a user to interact with the user interface of the computer terminal 10 (or mobile device).

[0053] Figure 1 The shown hardware structure block diagram can not only be used as an exemplary block diagram of the above-mentioned computer terminal 10 (or mobile device), but also as an exemplary block diagram of the above-mentioned server. In an alternative embodiment, Figure 2 is shown in a block diagram using the above Figure 1 shown computer terminal 10 (or mobile device) as a computing node in the computing environment 201 in one embodiment. Figure 2 is a structure block diagram of a computing environment according to an embodiment of the present application, such as Figure 2As shown, the computing environment 201 includes multiple computing nodes (such as servers, shown as 210-1, 210-2, … in the figure) running on a distributed network. Each computing node contains local processing and memory resources, and end users 202 can remotely run applications or store data in the computing environment 201. The applications can be provided as multiple services 220-1, 220-2, 220-3, and 220-4 in the computing environment 301, representing services "A", "D", "E", and "H" respectively.

[0054] End users 202 can provide and access services through a web browser or other software applications on the client. In some embodiments, the provisioning and / or requests of end users 202 can be provided to the ingress gateway 230. The ingress gateway 230 can include a corresponding proxy to handle the provisioning and / or requests for services (one or more services provided in the computing environment 201).

[0055] Services are provided or deployed according to various virtualization technologies supported by the computing environment 201. In some embodiments, services can be provided based on virtual machine (VM)-based virtualization, container-based virtualization, and / or similar means. VM-based virtualization can simulate a real computer by initializing a virtual machine and execute programs and applications without directly accessing any actual hardware resources. While virtualizing the machine with a virtual machine, according to container-based virtualization, containers can be launched to virtualize the entire operating system (OS) so that multiple workloads can run on a single operating system instance.

[0056] In one embodiment of container-based virtualization, several containers of a service can be assembled into a Pod (e.g., Kubernetes Pod). For example, as Figure 2 shown, service 220-2 can be equipped with one or more Pods 240-1, 240-2, …, 240-N (collectively referred to as Pods). Each Pod can include a proxy 245 and one or more containers 242-1, 242-2, …, 242-M (collectively referred to as containers). One or more containers in the Pod handle requests related to one or more corresponding functions of the service, and the proxy 245 generally controls network functions related to the service, such as routing, load balancing, etc. Other services can also be accompanied by Pods similar to this.

[0057] During operation, executing a user request from end user 202 may require invoking one or more services in the computing environment 201, and executing one or more functions of a service may require invoking one or more functions of another service. As Figure 2As shown, service "A" 220-1 receives a user request from end user 202 at ingress gateway 230. Service "A" 220-1 may invoke service "D" 220-2, and service "D" 220-2 may request service "E" 220-3 to perform one or more functions.

[0058] The computing environment described above may be a cloud computing environment where resource allocation is managed by a cloud service provider, allowing for the development of functions without considering the implementation, adjustment, or expansion of servers. This computing environment allows developers to execute code in response to events without building or maintaining complex infrastructure. Services can be split into sets of functions that can automatically scale independently, rather than scaling a single hardware device to handle potential loads.

[0059] In another alternative embodiment, Figure 3 A block diagram illustrates an embodiment of using the computer terminal 10 (or mobile device) described above Figure 1 as a service mesh. Figure 3 is a structural block diagram of a service mesh according to an embodiment of the present application. As Figure 3 shown, the service mesh 300 is mainly used to facilitate secure and reliable communication between multiple microservices. A microservice refers to decomposing an application into multiple smaller services or instances and running them on different clusters / machines.

[0060] As Figure 3 shown, the microservices may include application service instance A and application service instance B, and application service instance A and application service instance B form the functional application layer of the service mesh 300. In one implementation, application service instance A runs in the form of a container / process 308 on a machine / workload container group 314 (Pod), and application service instance B runs in the form of a container / process 310 on a machine / workload container group 316 (Pod).

[0061] In one implementation, application service instance A may be a product query service, and application service instance B may be a product order service.

[0062] As Figure 3As shown, application service instance A and mesh proxy (sidecar) 303 coexist in machine workload container group 614, and application service instance B and mesh proxy 305 coexist in machine workload container 314. Mesh proxy 303 and mesh proxy 305 form the data plane of service mesh 300. Among them, mesh proxy 303 and mesh proxy 305 run in the form of container / process 304 and container / process 306 respectively, can receive requests 312 for commodity query services, and there can be two-way communication between mesh proxy 303 and application service instance A, and between mesh proxy 305 and application service instance B. In addition, there can also be two-way communication between mesh proxy 303 and mesh proxy 305.

[0063] In one implementation, all traffic of application service instance A is routed to the appropriate destination through mesh proxy 303, and all network traffic of application service instance B is routed to the appropriate destination through mesh proxy 305. It should be noted that the network traffic mentioned here includes but is not limited to forms such as Hyper Text Transfer Protocol (abbreviated as HTTP), Representational State Transfer (abbreviated as REST), and high performance.

[0064] In one implementation, the function of extending the data plane can be achieved by writing a custom filter for the Envoy in service mesh 300. The service mesh proxy configuration can be used to correctly proxy service traffic in the service mesh, and achieve service intercommunication and service governance. Mesh proxy 303 and mesh proxy 305 can be configured to perform at least one of the following functions: service discovery, health checking, routing, load balancing, authentication and authorization, and observability.

[0065] As Figure 3 shown, the service mesh 300 also includes a control plane. Among them, the control plane can be a group of services running in a dedicated namespace, and these services are hosted by the managed control plane component 301 in machine / workload container group (machine / Pod) 302. As Figure 3As shown, the managed control plane component 301 communicates bidirectionally with the grid agents 303 and 305. The managed control plane component 301 is configured to perform some control management functions. For example, the managed control plane component 301 receives the telemetry data transmitted by the grid agents 303 and 305, and can further aggregate this telemetry data. For these services, the managed control plane component 301 can also provide user-facing application programming interfaces (APIs) to more easily manipulate network behavior and provide configuration data to the grid agents 303 and 305, etc.

[0066] In the above operating environment, the present application provides a method for determining the fidelity of qubit quantum gates in a quantum processor as shown in Figure 4 Shown. Figure 4 It is a flowchart of a method for determining the fidelity of qubit quantum gates in a quantum processor according to an embodiment of the present application. As shown in Figure 4 Shown, the method may include the following steps:

[0067] Step S402, determine the environmental qubit quantum gates associated with the two-qubit quantum gates in the quantum processor, where the two-qubit quantum gates interact with the environmental qubit quantum gates in the quantum processor.

[0068] In the technical solution provided in step S402 of the present application above, the environmental qubit quantum gates associated with the two-qubit quantum gates in the quantum processor can be determined, where the two-qubit quantum gates interact with the environmental qubit quantum gates in the quantum processor. The environmental qubit quantum gates can be composed of the environmental qubits around the two-qubit quantum gates, and can be one environmental qubit quantum, or a quantum gate of two or more environmental qubits. There is no specific limitation on the environmental qubit quantum gates here.

[0069] Optionally, in the quantum processor, the control effect of the two-qubit quantum gates will be affected by the surrounding qubits, and the qubits around the two-qubit quantum gates that affect the two-qubit quantum gates can be determined, so that the environmental qubit quantum gates associated with the two-qubit quantum gates in the quantum processor can be determined.

[0070] Step S404, determine the fidelity error of the environmental qubit quantum gates based on the fidelity error of the two-qubit quantum gates.

[0071] In the technical solution provided in step S404 of the present application above, to determine the fidelity error between the two-qubit quantum gates, the fidelity error of the environmental qubit quantum gates can be determined based on the fidelity error of the two-qubit quantum gates. Among them, the fidelity error of the two-qubit quantum gates can be the total error of the quantum processor.

[0072] Optionally, to determine the fidelity error of a two-bit quantum gate, the fidelity error of the two-bit quantum gate can be decomposed onto different environmental bit quantum gates, and the fidelity error decomposed onto each environmental bit quantum gate can be determined to obtain the fidelity error of the environmental bit quantum gate.

[0073] Step S406: Based on the fidelity error of the environmental bit quantum gate, determine the frequency of the environmental bit quantum gate.

[0074] In the technical solution provided in step S406 of the present application, the frequency of the environmental bit quantum gate can be determined based on the fidelity error of the environmental bit quantum gate.

[0075] In the embodiments of the present application, by decomposing the total error onto different environmental bit quantum gates, and based on the fidelity error assigned to the environmental bit quantum gate, it provides guidance for the selection of the frequency of the environmental bit quantum gate.

[0076] Step S408: Based on the frequency of the environmental bit quantum gate, determine the fidelity of the two-bit quantum gate.

[0077] In the technical solution provided in step S408 of the present application, the frequency of the environmental bit quantum gate can be obtained, and based on the frequency of the environmental bit quantum gate, the fidelity of the two-bit quantum gate can be determined.

[0078] For example, the corresponding relationship between the fidelity of the environmental bit quantum gate and the two-bit quantum gate can be obtained in advance, so that the fidelity of the two-bit quantum gate can be determined based on the frequency of the environmental bit quantum gate.

[0079] Through steps S402 to S408 of the present application, the environmental bit quantum gates associated with the two-bit quantum gate in the quantum processor are determined, where the two-bit quantum gate and the environmental bit quantum gate interact in the quantum processor; based on the fidelity error of the two-bit quantum gate, the fidelity error of the environmental bit quantum gate is determined; based on the fidelity error of the environmental bit quantum gate, the frequency of the environmental bit quantum gate is determined; based on the frequency of the environmental bit quantum gate, the fidelity of the two-bit quantum gate is determined. That is to say, the embodiments of the present application consider the influence of the environmental bit quantum gates associated with the two-bit quantum gate in the quantum processor on the two-bit quantum gate, redefine the fidelity, decompose the fidelity error of the two-bit quantum gate onto different environmental bit quantum gates, provide guidance for the selection of the frequency of the environmental bit quantum gate, so as to determine the fidelity that meets the conditions, achieving the technical effect of improving the accuracy of determining the fidelity of the two-bit quantum gate, and solving the technical problem of being unable to determine the fidelity of the two-bit quantum gate.

[0080] The above method of this embodiment will be further introduced below.

[0081] As an alternative implementation, in step S404, determining the fidelity error of the environmental qubit gate based on the fidelity error of the two-qubit gate includes: decomposing the fidelity error of the two-qubit gate onto different environmental qubit gates to obtain the fidelity errors of different environmental qubit gates.

[0082] In this embodiment, the fidelity error of the two-qubit gate can be determined, and the fidelity error can be decomposed onto different environmental qubit gates, thereby obtaining the fidelity errors of different environmental qubit gates.

[0083] As an alternative implementation, in step S406, determining the frequency of the environmental qubit gate based on the fidelity error of the environmental qubit gate includes: scanning the superconducting circuit of the quantum processor to obtain multiple parameters; respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the multiple parameters.

[0084] In this embodiment, scanning the superconducting circuit of the quantum processor to determine multiple parameters in the superconducting circuit, and the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate can be determined based on the multiple parameters. Among them, the parameters can be single-qubit parameters, the number of single qubits in the multi-qubit model, local extreme offset, etc. Here is only an example, and no specific restrictions are imposed on the parameters.

[0085] Optionally, the superconducting circuit can be scanned to determine multiple parameters in the superconducting circuit, and the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate can be determined respectively based on the multiple parameters.

[0086] As an alternative implementation, the multiple parameters include single-qubit parameters. Among them, respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the multiple parameters includes: determining the frequency of the environmental qubit gate and the frequency of the coupler corresponding to the fidelity error of the environmental qubit gate based on the single-qubit parameters; among them, determining the fidelity of the two-qubit gate based on the frequency of the environmental qubit gate includes: determining the fidelity of the two-qubit gate at the frequency of the environmental qubit gate and the frequency of the coupler.

[0087] In this embodiment, the superconducting circuit can be composed of at least one single qubit, and the single-qubit parameters in the superconducting circuit can be determined. Among them, the single-qubit parameters can include the single-qubit frequency. For example, it can be the frequency of the environmental qubit in the environmental qubit gate and the frequency of the two-qubit gate, etc. Here is only an example of the single-qubit parameters, and no specific restrictions are made. The fidelity of the two-qubit gate can be determined at the frequency of the environmental qubit gate and the frequency of the coupler.

[0088] For example, the fidelity error of a two-bit quantum gate can be determined, the fidelity error can be allocated to the environmental bit quantum gate, and based on single-bit parameters, the frequencies of the environmental bit quantum gate corresponding to the fidelity error of the environmental bit quantum gate and the frequency of the coupler can be determined. For example, the frequency of the environmental bit quantum gate can be 2, -3, etc., and the coupler frequency can be 0, -1, etc. It should be noted that the numbers here are only for illustrative purposes and do not impose specific restrictions on the frequency magnitudes. The fidelity of the two-bit quantum gate can be determined at the frequencies of the environmental bit quantum gate and the coupler.

[0089] Optionally, in order to suppress the resonance between bits, the embodiments of the present application select as few frequency ranges as possible for the environmental bit quantum gate and the coupler. Since when the frequency difference between any two same-type qubits is less than 50 MHz, the resonance phenomenon between the qubit quanta is relatively obvious and has an adverse effect on the gate operation. Therefore, in the embodiments of the present application, the frequency difference between adjacent environmental bit quantum gates and couplers is set to be greater than 50 MHz.

[0090] As an alternative implementation, multiple parameters include the number of single-bit states in the multi-bit model. Among them, based on multiple parameters respectively, the frequency of the environmental bit quantum gate corresponding to the fidelity error of the environmental bit quantum gate is determined, including: based on the number of single-bit states in the multi-bit model, the frequencies of the environmental bit quantum gate corresponding to the fidelity error of the environmental bit quantum gate and the frequency of the coupler are determined; based on the frequency of the environmental bit quantum gate, the fidelity of the two-bit quantum gate is determined, including: the fidelity corresponding to the frequency of the environmental bit quantum gate and the frequency of the coupler is determined as the fidelity of the two-bit quantum gate.

[0091] In this embodiment, multiple parameters can include the number of single-bit states in the multi-bit model. The number of single-bit states in the multi-bit model can be determined. Based on the number of single-bit states in the multi-bit model, the frequencies of the environmental bit quantum gate corresponding to the fidelity error of the environmental bit quantum gate and the frequency of the coupler can be determined, and the fidelity corresponding to the frequencies of the environmental bit quantum gate and the coupler can be determined as the fidelity of the two-bit quantum gate. Among them, the environmental bit quantum gate can include environmental bits (environmental qubits), and the coupler can include environmental couplers.

[0092] Optionally, considering that the more the number of single-bit states in the multi-bit model, the smaller the time interval value and the longer the running duration. The number of single-bit states in the multi-bit model can be determined. Based on the number of single-bit states in the multi-bit model, within an acceptable accuracy range, the frequencies of the environmental bit quantum gate corresponding to the fidelity error of the environmental bit quantum gate and the frequency of the coupler can be determined, and the fidelity corresponding to the frequencies of the environmental bit quantum gate and the coupler can be determined as the fidelity of the two-bit quantum gate.

[0093] For example, it can be pre-determined that the single-bit state of the multi-bit model is a 3-bit (qubit, abbreviated as Q) model state. Based on the selection reference table of 3-bit (qubit, abbreviated as Q) model state parameters, and based on the number of single-bit states of the multi-bit model, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate and the frequency of the coupler can be determined. The fidelity corresponding to the frequency of the environmental qubit quantum gate and the frequency of the coupler can be determined as the fidelity of the two-bit quantum gate. If, in the selection reference table of parameters, the frequency of the environmental qubit quantum gate is determined to be 3 and the frequency of the coupler is 8, since the fidelity corresponding to the frequency of the environmental qubit quantum gate and the frequency of the coupler in the selection reference table of parameters is 0.998531, the fidelity of the two-bit quantum gate can be determined to be 0.998531. The above numbers are only for illustrative purposes and are not subject to specific limitations.

[0094] As an alternative implementation, multiple parameters include offset local extrema. Among them, based on multiple parameters respectively, determining the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate includes: determining the true local extremum based on the offset local extremum; determining the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate based on the true local extremum; determining the fidelity of the two-bit quantum gate based on the frequency of the environmental qubit quantum gate includes: determining the fidelity corresponding to the frequency of the environmental qubit quantum gate as the fidelity of the two-bit quantum gate.

[0095] In this embodiment, multiple parameters can include offset local extrema. The true local extremum can be determined based on the offset local extremum. Based on the true local extremum, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate can be determined. The fidelity corresponding to the frequency of the environmental qubit quantum gate can be determined as the fidelity of the two-bit quantum gate. Among them, the offset regional extremum can include a maximum point, which can be a non-true extremum point located at the boundary. For example, it can be (0.423, 45, 0.921256). The true local extremum can be a true extremum point determined after expanding the range. For example, it can be (0.413, 66, 0.9910813). It should be noted that the above numbers are only for illustrative purposes and are not subject to specific limitations on the size of the numbers.

[0096] For example, the offset local extreme values of the type-B superconducting circuit are determined, and the maximum value and the bad points with a fidelity much lower than the remaining surrounding points are obtained in the offset local extreme values. There are two maximum points (0.426, 35, 0.890727) and (0.423, 45, 0.921256) within the range of the offset local extreme values. Since there is a relatively significant offset of the extreme points when determining the extreme points of this type of superconducting circuit in advance, that is, the extreme points in the offset local extreme values are not the true local extreme values and may only be located at the boundary and not the true extreme points. Therefore, the true local extreme value (0.413, 66, 0.9910813) can be determined based on the maximum point (0.423, 45, 0.921256). After expanding the range, the true local extreme value can be found. Based on the true local extreme value, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate can be determined, and the fidelity corresponding to the frequency of the environmental qubit quantum gate can be determined as the fidelity of the two-qubit quantum gate.

[0097] As an alternative implementation, multiple parameters include basis vectors. Among them, based on the multiple parameters respectively, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate is determined, including: determining the evolution result of the quantum processor under the basis vector; based on the evolution result, determining the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate, where the magnitude of the fidelity error of the environmental qubit quantum gate is less than the magnitude threshold.

[0098] In this embodiment, multiple parameters include basis vectors. Among them, the basis vectors can include product basis vectors, open-source library basis vectors (eigen basis vectors), etc. This is only an example here and does not specifically limit the types of basis vectors. The evolution result of the quantum processor under the basis vector can be determined, and based on the evolution result, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate can be determined, where the magnitude of the fidelity error of the environmental qubit quantum gate can be less than the magnitude threshold. For example, it can be of the order of 0.001. The evolution result can include the evolution result under the product basis vector, the evolution result under the eigen basis vector, etc. This is only an example here and does not specifically limit the evolution result.

[0099] The evolution results under the product basis vector and the eigen basis vector are determined, and the character string (phiext) and the gate operation parameter (time_gate) are changed. The choice of the basis vector has no obvious influence on the trend of the fidelity change, and the error is of the order of 0.001. If the actual measurement is performed in the eigenbasis, the evolution result can be the evolution result under the eigen basis vector. This is only an example here, and the embodiments of the present application do not specifically limit the choice of the basis vector.

[0100] For example, the evolution result of a superconducting circuit in the basis vectors can be determined, and the evolution results in the product basis vectors, eigen basis vectors, etc. can be obtained. Based on the evolution results, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate can be determined, and based on the frequency of the environmental qubit quantum gate, the fidelity of the two-qubit quantum gate can be determined.

[0101] For another example, for multi-qubit classes, the transformation matrices u_b3q_to_b3 and u_b7q_to_b7 between the product basis vectors and eigen basis vectors can be provided in advance. The transformation matrix can be denoted as U. For any matrix A, there is a basis vector transformation operation:

[0102]

[0103] where A EIGEN can be the matrix obtained after the basis vector change, can be the conjugate transpose matrix of the transformation matrix, A PRODUCT can be the matrix in the product basis vectors. Due to the process of time evolution (trotter), it is impossible to split the two-qubit interaction into the simple direct product form of single-qubit states in the eigen basis vectors. Therefore, it is necessary to transform from the eigen basis vectors to the product basis vectors for time evolution. For example, for the initial state final state

[0104]

[0105] The above can be reflected in the program as setting the initial state in the eigen basis vectors using the transformation matrix U to transform it to the product basis vectors performing time evolution with the trotter process finally changing the result back to the eigen basis vectors so as to obtain the evolution result in the eigen basis vectors.

[0106] It should be noted that since u_b*t_to_b* has not been sorted, when performing the eigen-product space transformation, the u_b*q_to_b* in the multi-qubit class can be used instead of u_b*t_to_b*, which can improve the efficiency and accuracy of the transformation.

[0107] As an optional implementation manner, the method includes that multiple parameters include waveform parameters, and the waveform parameter is the maximum value point determined based on the evolution result. Among them, based on the multiple parameters respectively, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate is determined, including: determining the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate based on the waveform parameter.

[0108] In this embodiment, multiple parameters may include waveform parameters, where the waveform parameters may be the maximum points determined based on the evolution result. The frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate may be determined based on the waveform parameters, and the fidelity of the two-qubit gate may be determined based on the frequency of the environmental qubit gate.

[0109] For example, for the evolution result in the eigen basis, when t takes the local maximum point 33 and two local maxima are searched within a relatively large range of the two-dimensional variable (sigma - phiext), it can be determined according to the pre-experiment results that the appropriate waveform parameters can be the parameters that meet the conditions without considering the environmental qubit, that is, the maximum point near sigma = 7. It should be noted that the above numbers are only for illustration and do not impose specific limitations.

[0110] As an alternative embodiment, the method includes that multiple parameters include the local maxima of the evolution result. Based on the multiple parameters respectively, determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate includes: determining the leakage information of the quantum processor at the local maximum; determining the qubit state that the environmental qubit gate corresponding to the leakage information jumps to, and determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate in the qubit state; based on the frequency of the environmental qubit gate, determining the fidelity of the two-qubit gate includes: determining the fidelity corresponding to the frequency of the environmental qubit gate as the fidelity of the two-qubit gate.

[0111] In this embodiment, multiple parameters include the local maxima in the evolution result. The leakage information of the quantum processor at the local maximum can be determined, the qubit state that the environmental qubit gate corresponding to the leakage information jumps to can be determined, the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate in the qubit state can be determined, and the fidelity corresponding to the frequency of the environmental qubit gate can be determined as the fidelity of the two-qubit gate. Among them, the local maximum can be used to characterize the maximum fidelity. For example, it can be (0.426, 7.0, 0.609772). The leakage information can be used to represent the information that causes the fidelity error.

[0112] For example, the evolution result of the 7Q model in the eigen basis can be determined. The local maximum value is determined to be (0.426, 7.0, 0.909772) from the evolution result, and the leakage information of the evolution result is determined. The maximum value in the leakage information is (0.424, 5.4, 0.237816), and the minimum value is (0.428, 8.6, 0.165885). The difference between the phase modulation (CZphase) of the evolution result and π (or -π) is determined, with the unit being π. The upper left region of the evolution result is positive (close to π), and the lower right region is negative (close to -π). The maximum and minimum values in the positive region of the leakage area are (0.994814, 0.735788) respectively, and the maximum and minimum values in the negative region are (-0.768197, -0.999719) respectively. Analyzing the leakage information at the maximum value (0.426, 7.0, 0.909772), czphase = 0.988097π and leakage = 0.199811 are obtained. Further, the qubit state that the environmental qubit gate corresponding to the leakage information jumps to can be determined. It is determined that the component with the largest leakage information is the second environmental qubit gate, and the second environmental qubit gate jumps to the 1 state, which is much larger than other components. It should be noted that the total leakage and the leakage of each qubit state are not the same algorithm, so the sum of the leakage of each qubit state is not equal to the total leakage.

[0113] In this embodiment, the calculation matrix of the maximum component can be taken out, the matrix elements can be observed, and it can be determined that the probability leakage occurs in two processes: |001(0000)> → |000(0001)> and |101(0000)> → |100(0001)>. Among the 7 numbers, the 1st and 3rd bits represent the central qubit state, the 2nd bit represents the central coupler state, the 4th and 6th bits represent the environmental coupler states, and the 5th and 7th bits represent the environmental qubit states, so as to determine the environmental qubit states. The frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate with respect to the qubit state can be determined; the fidelity corresponding to the frequency of the environmental qubit gate is determined as the fidelity of the two-qubit quantum gate.

[0114] For another example, for the two-qubit quantum gate evolution matrix U, any initial state v of the data qubit is taken, satisfying Then the final state is Uv. An optimization algorithm (such as the gradient descent method) is used to find v in the parameter space such that Then the total leakage can be determined to be (1 - L), where L can be the probability that a given environmental qubit leaks to a specific final state.

[0115] At the same time, in order to calculate the magnitude of the leakage of a given environmental qubit, a set leakage information channel (leakage channel) can be set, for example, |00e >→|01 e > The four final states (|00>, |01>, |10>, |11>) of the two - qubit quantum gate evolution matrix will become the corresponding four final states (|00(01 e )>, |01(01 e )>, |10(01 e )>, |11(01 e )>). Thus, the four initial states (|00(00 e )>, |01(00 e )>, |10(00 e )>, |11(00 e )>) can be taken from the evolution matrix of the entire space and corresponding to the new four final states (|00(01 e )>, |01(01 e )>, |10(01 e )>, |11(01 e )>) to form a 4 - by - 4 matrix U. Calculate:

[0116]

[0117] Among them, the magnitude of the L value can be the probability that a given environmental qubit leaks to a specific final state; the evolution matrix can be:

[0118]

[0119] Based on the above - mentioned calculation method, the probability that a given environmental qubit leaks to a specific final state can be determined, thereby determining the total leakage.

[0120] As an alternative implementation, the method includes that the quantum processor includes inductively - coupled fluxonium - type qubits, or the quantum processor includes transmon - type qubits.

[0121] In this embodiment, the superconducting quantum chip can include fluxonium - type qubits. By using fluxonium - type qubits, low - frequency charge drift can be well suppressed, while the high - frequency oscillation part of the charge is retained. When the loop magnetic flux of the fluxonium changes, its energy level structure can be adjusted within a large range (0.5 - 10 GHz). Thus, when it is determined that the fidelity between two - qubit quantum gates is low, it is convenient to quickly adjust the parameters of the quantum chip.

[0122] Optionally, the superconducting quantum chip can include transmon - type qubits. By using transmon - type qubits, the manipulation and readout of qubits can be realized.

[0123] In the embodiments of the present application, considering the influence of the environmental qubit gates associated with the two-qubit gates in the quantum processor on the two-qubit gates, the fidelity is redefined, and the fidelity error of the two-qubit gates is decomposed onto different environmental qubit gates, providing guidance for the frequency selection of the environmental qubit gates, and then determining the fidelity that meets the conditions, achieving the technical effect of improving the accuracy of determining the fidelity of the two-qubit gates and solving the technical problem of being unable to determine the fidelity of the two-qubit gates.

[0124] The embodiments of the present application also provide another method for determining the fidelity of the qubit gates in the quantum processor, and this method can be applied to the software service side (Software-as-a-Service, abbreviated as SaaS).

[0125] Figure 5 is a flowchart of another method for determining the fidelity of the qubit gates in the quantum processor according to the embodiments of the present application, as Figure 5 shown, and this method may include the following steps.

[0126] Step S502, obtain the environmental qubit gates associated with the two-qubit gates in the quantum processor by calling the first interface, where the first interface includes a first parameter, and the parameter value of the first parameter is the two-qubit gates and the environmental qubit gates, and the two-qubit gates and the environmental qubit gates interact with each other in the quantum processor.

[0127] In the technical solution provided in step S502 of the present application above, the first interface may be an interface for data interaction between the server and the client, and the client can obtain the environmental qubit gates associated with the two-qubit gates in the quantum processor by calling the first interface. The two-qubit gates and the environmental qubit gates are used as a first parameter of the first interface to achieve the purpose of obtaining the environmental qubit gates associated with the two-qubit gates in the quantum processor, where the two-qubit gates and the environmental qubit gates interact with each other in the quantum processor.

[0128] Step S504, determine the fidelity error of the environmental qubit gates based on the fidelity error of the two-qubit gates.

[0129] Step S506, determine the frequency of the environmental qubit gates based on the fidelity error of the environmental qubit gates.

[0130] Step S508, determine the fidelity of the two-qubit gates based on the frequency of the environmental qubit gates.

[0131] Step S510, output the fidelity of the two-qubit gates by calling the second interface, where the second interface includes a second parameter, and the parameter value of the second parameter is the fidelity of the two-qubit gates.

[0132] In the technical solution provided in step S510 of the present application, the second interface can be an interface for data interaction between the server and the client. The server can output the fidelity of the two-bit quantum gate and send it to the client, so that the client can output the fidelity of the two-bit quantum gate into the second interface as a parameter of the second interface, achieving the purpose of sending the two-bit quantum gate to the client.

[0133] Figure 6 It is a schematic diagram of a computer device accessing a private network according to an embodiment of the present application. As Figure 6 shown, the environmental bit quantum gate associated with the two-bit quantum gate in the quantum processor can be obtained by calling the first interface. The computer device executes: step S602, determining the fidelity error of the environmental bit quantum gate based on the fidelity error of the two-bit quantum gate. Step S604, determining the frequency of the environmental bit quantum gate based on the fidelity error of the environmental bit quantum gate. Step S606, determining the fidelity of the two-bit quantum gate based on the frequency of the environmental bit quantum gate.

[0134] Optionally, the platform can output the fidelity of the two-bit quantum gate by calling the second interface. Among them, the second interface can be used to send the fidelity of the two-bit quantum gate to the client, so as to achieve the purpose of the client outputting the fidelity of the two-bit quantum gate.

[0135] The embodiment of the present application also provides another method for determining the fidelity of the bit quantum gate in the quantum processor. Figure 7 It is a flowchart of another method for determining the fidelity of the bit quantum gate in the quantum processor according to an embodiment of the present application. As Figure 7 shown, the method may include the following steps:

[0136] Step S702, obtaining the environmental bit quantum gate associated with the two-bit quantum gate in the quantum processor from the quantum platform, where the two-bit quantum gate and the environmental bit quantum gate interact with each other in the quantum processor.

[0137] Step S704, determining the fidelity error of the environmental bit quantum gate based on the fidelity error of the two-bit quantum gate.

[0138] Step S706, determining the frequency of the environmental bit quantum gate based on the fidelity error of the environmental bit quantum gate.

[0139] Step S708, determining the fidelity of the two-bit quantum gate based on the frequency of the environmental bit quantum gate.

[0140] Step S710, returning the fidelity of the two-bit quantum gate to the quantum platform.

[0141] Through the above steps S702 to S710 of this application, obtain the environmental qubit gates associated with the two-qubit gates in the quantum processor from the quantum platform, where the two-qubit gates interact with the environmental qubit gates in the quantum processor; determine the fidelity error of the environmental qubit gates based on the fidelity error of the two-qubit gates; determine the frequency of the environmental qubit gates based on the fidelity error of the environmental qubit gates; determine the fidelity of the two-qubit gates based on the frequency of the environmental qubit gates; and return the fidelity of the two-qubit gates to the quantum platform. This achieves the technical effect of improving the accuracy of determining the fidelity of two-qubit gates and solves the technical problem of being unable to determine the fidelity of two-qubit gates.

[0142] Embodiment 2

[0143] In the design process of superconducting quantum chips, usually only the fidelity of isolated two-qubit gates (quantum gates) is considered. However, in a real quantum chip, two-qubit gates will inevitably interact with the surrounding qubits. But currently, there is no related technology to characterize the fidelity of two-qubit gates in a multi-qubit environment.

[0144] In order to characterize the fidelity of two-qubit gates in a multi-qubit environment, the embodiment of this application proposes a method for realizing tunable inductive coupling (fluxonium) of high-fidelity two-qubit gates in a multi-qubit environment. This method redefines the fidelity and searches for the satisfied fidelity by scanning the parameters in the superconducting circuit. By decomposing the total error onto different environmental qubits, it provides guidance for the frequency selection of environmental qubits.

[0145] The following further introduces the method for realizing tunable inductive coupling of high-fidelity two-qubit gates in the embodiment of this application.

[0146] Scan the superconducting circuit of the quantum processor to determine various parameters in the superconducting circuit. Based on the various parameters, the frequency of the environmental qubit gates corresponding to the fidelity error of the environmental qubit gates can be determined. Among them, the parameters can be single-qubit parameters, the number of single qubits in the multi-qubit model, local extreme offset amounts, etc. Here, it is only for illustration and does not specifically limit the parameters.

[0147] Optionally, the superconducting circuit can be scanned to determine various parameters in the superconducting circuit, and the frequency of the environmental qubit gates corresponding to the fidelity error of the environmental qubit gates can be determined respectively based on the various parameters.

[0148] In this embodiment, the fidelity error of the two-qubit quantum gate can be determined, the fidelity error can be allocated to the environmental qubit quantum gate, and based on the single-bit parameters, the frequencies of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate and the frequency of the coupler can be determined. At the frequencies of the environmental qubit quantum gate and the coupler, the fidelity of the two-qubit quantum gate can be determined. Figure 8 It is a schematic diagram of the frequency selection of a quantum bit and a coupler according to an embodiment of the present application, as Figure 8 shown, black represents the coupler, and white represents the data qubit. Among them, the size of the numbers in the coupler and the qubit represents the level of the selected frequency. For every difference of 1 in the numbers, the frequency difference > 50 MHz. The frequencies of the qubits can be determined to be 4, -3, 3, -2, -4, 1, -1, etc., and the coupler frequencies can be 1, -1, 2, -2, 3, -3, etc.

[0149] Optionally, in order to suppress the resonance between qubits, the embodiment of the present application selects the frequency ranges of the environmental qubit quantum gate and the coupler to be as small as possible. Since when the frequency difference between any two qubits of the same type is less than 50 MHz, the resonance phenomenon between the qubit quanta is relatively obvious, which has an adverse effect on the gate operation. Therefore, in the embodiment of the present application, the frequency difference between adjacent environmental qubit quantum gates and couplers is set to be greater than 50 MHz.

[0150] In this embodiment, considering that in the multi-bit model, the larger the number of single-bit states, the smaller the time interval value, and the longer the running duration. The number of single-bit states of the multi-bit model can be determined, and based on the number of single-bit states of the multi-bit model, within an acceptable accuracy range, the frequencies of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate and the frequency of the coupler can be determined. The fidelity corresponding to the frequencies of the environmental qubit quantum gate and the coupler can be determined as the fidelity of the two-qubit quantum gate.

[0151] For example, a reference table for selecting model state parameters can be determined in advance, and various processing methods can be used. For example, the processing method can be the Adams method (sesolve). Table 1 is a reference data of model state parameters for a 3-qubit model. As shown in Chart 1, the results obtained by sesolve can be obtained. On the right side, the results marked with order0 are the results of the 0th-order Trotter, and the rest are the results of the 2nd-order Trotter, etc. The number of single-bit states in the multi-bit model can be determined. Since the larger the number of states, the smaller the value of the time interval and the longer the running time. The results obtained by sesolve can be used as a standard. Within an acceptable accuracy range (such as 10^-4), within an acceptable accuracy range, a set of parameters that can balance accuracy and time consumption can be selected. For example, a set of parameters with single-bit 1 (Q1) being 3, the coupler being 8, single-bit 1 (Q2) being 3, and the time interval (n_slot_per_ns) being 100 can be selected as the parameters for the 3Q model. The frequency corresponding to the model can be determined based on the time interval.

[0152] Table 1 Reference data of model state parameters for a 3-qubit model

[0153]

[0154]

[0155] As shown in Table 1, if in the reference table for parameter selection, the frequency of the environmental qubit gate is determined to be 3 and the frequency of the coupler is 8, since the fidelity corresponding to the frequency of the environmental qubit gate and the frequency of the coupler in the reference table for parameter selection is 0.998531, the fidelity of the two-bit qubit gate can be determined to be 0.998531. The above numbers are only for illustrative purposes and are not subject to specific limitations.

[0156] In this embodiment, the true local extremum can be determined based on the offset local extremum. Based on the true local extremum, the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate can be determined, and the fidelity corresponding to the frequency of the environmental qubit gate can be determined as the fidelity of the two-bit qubit gate.

[0157] For example, Figure 9 is a schematic diagram of the fidelity of a 15-qubit model (15Q model) according to an embodiment of the present application. As Figure 9As shown, the slanted-striped dots are the global maxima of the entire figure, and the black dots are the bad points where the fidelity is much smaller than the rest of the surrounding points. We found that there are two maximum points (0.426, 35, 0.890727) and (0.423, 45, 0.921256) within the range shown in the figure, and there is a relatively significant offset problem of the extreme point of the 15Q model (0.426, 35, 0.890727) compared to the 3Q model (0.43, 32, 0.998568). Therefore, Figure 9 The global maximum point shown in the figure is not the original extreme point. Considering the limitations in terms of coherence time and the parameters that meet the conditions without considering the environmental qubits, the extreme point near t = 32 can be selected as the maximum point.

[0158] Since there will be a relatively significant offset of the extreme points when pre-determining the extreme points of this type of superconducting circuit, that is, the extreme points in the offset local extreme values are not the true local extreme values and may only be located at the boundary and not the true extreme points. Therefore, the true local extreme value can be determined based on the maximum point (0.423, 45, 0.921256), and the range of the above maximum point can be expanded. Figure 10 is a schematic diagram of the result of expanding the maximum value according to an embodiment of the present application. As Figure 10 shown, the true local extreme value (0.413, 66, 0.9910813) can be found after expanding the range. Based on the true local extreme value, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate can be determined, and the fidelity corresponding to the frequency of the environmental qubit quantum gate can be determined as the fidelity of the two-qubit quantum gate.

[0159] In this embodiment, multiple parameters including the basis vectors can determine the evolution result of the quantum processor under the basis vectors, and based on the evolution result, the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate can be determined.

[0160] For example, Fig. 11(a) is a schematic diagram of an evolution result according to an embodiment of the present application. Fig. 11(a) is the evolution result of the 7Q model under the product basis vector. Fig. 11(b) is a schematic diagram of another evolution result according to an embodiment of the present application. Fig. 11(b) is the evolution result of the 7Q model under the eigen basis vector. In the above two figures, the horizontal axis is the data of the character string parameter, and the vertical axis is the value of the gate operation parameter. The choice of the basis vector has no obvious influence on the trend of the change in fidelity. The maximum value in Fig. 11(a) is (0.43, 77, 0.996171), and the maximum value in Fig. 11(b) is (0.43, 77, 0.997159), and the error is on the order of 0.001. If the actual measurement is carried out in the eigenbasis, the evolution result can be the evolution result under the eigen basis vector.

[0161] For another example, for 3Q and 7Q multi-bit classes, the transformation matrices u_b3q_to_b3 and u_b7q_to_b7 between the product basis and the eigen basis can be provided in advance. The transformation matrices can be denoted as U. For any matrix A, there is a basis transformation operation:

[0162]

[0163] where A EIGEN can be the matrix obtained after the basis change, can be the conjugate transpose matrix of the transformation matrix, and A PRODUCT can be the matrix in the product basis. Due to the process of time evolution, it is impossible to split the two-bit interaction into the simple direct product form of single-bit states in the eigen basis. Therefore, it is necessary to transform from the eigen basis to the product basis for time evolution. For example, for the initial state final state

[0164]

[0165] The above can be reflected in the program as setting the initial state in the eigen basis using the transformation matrix U to transform it to the product basis performing time evolution using the trotter process finally changing the result back to the eigen basis so as to obtain the evolution result in the eigen basis.

[0166] It should be noted that when performing the eigen-product space transformation, the transformation matrix from the eigen space to the product space in the multi-bit class is used. Since u_b*t_to_b* has not been sorted, the u_b*q_to_b* in the multi-bit class can be used instead of u_b*t_to_b* during the eigen-product space transformation, thereby improving the efficiency and accuracy of the transformation.

[0167] Optionally, FIG. 12(a) is a schematic diagram of another evolution result according to an embodiment of the present application. FIG. 12(a) is another evolution result of the 7Q model in the eigen basis. Here, t takes the local maximum point 33. Two local maxima are searched within a relatively large range of two-dimensional variables. Therefore, the waveform parameters that meet the conditions can be selected as the parameters that meet the conditions when not considering the environmental bits, that is, the maximum point near sigma = 7

[0168] For example, optionally, regarding the determination of phase modulation, it can be: only considering the relative phases of the diagonal elements of the two-qubit quantum gate evolution matrix, which can generally be written in the following form:

[0169]

[0170] where is CZphase, θ 1 and θ 2 can be the angles of the time evolution of the first and second data qubits without considering the interaction, respectively.

[0171] Therefore, by determining the relative phases of the four elements on the diagonal of the evolution matrix, the CZphase of the evolution matrix can be obtained. Based on the desired gate operation, CZphase = π can be determined.

[0172] Furthermore, error analysis can be performed on the extreme points near sigma = 7. FIG. 12(b) is a schematic diagram of another evolution result according to an embodiment of the present application. FIG. 12(b) can be the evolution result of the 7Q model in the eigen basis, and the local maximum is (0.426, 7.0, 0.909772).

[0173] Perform error analysis on the extreme points. Figure 13 is a schematic diagram of the leakage information of an evolution result according to an embodiment of the present application. As Figure 13 shown, in the leakage information of the evolution result within the same range as the evolution result, the maximum value is in the upper left corner (0.424, 5.4, 0.237816), and the minimum value is in the lower right corner (0.428, 8.6, 0.165885); Figure 14 is a schematic diagram of the difference in phase modulation according to an embodiment of the present application. As Figure 14 shown, the difference between the phase modulation of the evolution result within the same range above and π (or -π), in units of π, is positive in the upper left region (close to π) and negative in the lower right region (close to -π). The closer the numerical value in the figure is to 0, the better the effect. Therefore, the maximum and minimum values in the positive region are (0.994814, 0.735788) respectively, and the maximum and minimum values in the negative region are (-0.768197, -0.999719) respectively.

[0174] Then, the analysis of the leakage information components at the maximum value (0.426, 7.0, 0.909772) can be carried out. Here, czphase = 0.988097π, leakage = 0.199811. Table 2 is the analysis table of the leakage information components of each bit. As can be seen from Table 2, the component with the largest leakage information is that the second environmental bit quantum gate jumps to the 1 state, which is much larger than other components. It should be noted that the total leakage and the leakage of each bit state are not the same algorithm, so the sum of the leakage of each bit state is not equal to the total leakage.

[0175] Table 2 Analysis Table of Leakage Components of Each Bit

[0176]

[0177] Take out the calculation matrix of the largest component, observe the matrix elements, and determine that the largest probability leakage occurs in the two processes |001(0000)> → |000(0001)> and |101(0000)> → |100(0001)>. Among the 7 numbers, the 1st and 3rd bits represent the central qubit state, the 2nd bit represents the central coupler state, the 4th and 6th bits represent the environmental coupler state, and the 5th and 7th bits represent the environmental qubit state

[0178]

[0179] For another example, for the two-bit quantum gate evolution matrix U, randomly take the initial state v of the data bit, satisfying Then the final state is Uv. Use the optimization algorithm (for example, the gradient descent method) to find v in the parameter space so that Then the total leakage can be determined as (1 - L), where L can be the probability that a given environmental bit leaks to a specific final state.

[0180] At the same time, in order to calculate the magnitude of the leakage of a given environmental bit, a leakage information channel can be set, for example, |00 e > → |01 e >. The four final states (|00>, |01>, |10>, |11>) of the two-bit quantum gate evolution matrix will become the corresponding four final states (|00(01 e )>, |01(01 e )>, |10(01 e )>, |11(01 e )>), so that four initial states (|00(00 e )>, |01(00 e )>, |10(00 e)>, |11(00 e )> corresponds to the new four final states (|00(01 e )>, |01(01 e )>, |10(01 e )>, |11(01 e )> The 16 matrix elements of form a 4x4 matrix U, calculate:

[0181]

[0182] Among them, the magnitude of the L value can be the probability that the given environmental bit leaks to a specific final state; the evolution matrix can be:

[0183]

[0184] Based on the above calculation method, the probability that a given environmental bit leaks to a specific final state can be determined, thereby determining the total leakage.

[0185] In the embodiments of the present application, considering the influence of the environmental bit quantum gate associated with the two-bit quantum gate in the quantum processor on the two-bit quantum gate, the fidelity is redefined, and the fidelity error of the two-bit quantum gate is decomposed into different environmental bit quantum gates, providing guidance for the frequency selection of the environmental bit quantum gate, thereby determining the fidelity that meets the conditions, achieving the technical effect of improving the accuracy of determining the fidelity of the two-bit quantum gate, and solving the technical problem of being unable to determine the fidelity of the two-bit quantum gate.

[0186] It should be noted that, for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present application is not limited by the described action sequence, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to the present application.

[0187] Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to enable a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods of the various embodiments of the present application.

[0188] Embodiment 3

[0189] According to the embodiments of the present application, there is also provided a device for determining the fidelity of qubit quantum gates in the quantum chip for implementing the method for determining the fidelity of qubit quantum gates in the quantum chip as described above. Figure 4 as shown in the quantum chip for implementing the method for determining the fidelity of qubit quantum gates.

[0190] Figure 15 is a schematic diagram of a method for determining the fidelity of qubit quantum gates in a quantum chip according to an embodiment of the present application. As Figure 15 shown, the device 1500 for determining the fidelity of qubit quantum gates in the quantum chip may include: a first determination unit 1502, a second determination unit 1504, a third determination unit 1506, and a fourth determination unit 1508.

[0191] The first determination unit 1502 is configured to determine the environmental qubit quantum gates associated with the two-qubit quantum gates in the quantum processor, where the two-qubit quantum gates and the environmental qubit quantum gates interact with each other in the quantum processor.

[0192] The second determination unit 1504 is configured to determine the fidelity error of the environmental qubit quantum gates based on the fidelity error of the two-qubit quantum gates.

[0193] The third determination unit 1506 is configured to determine the frequency of the environmental qubit quantum gates based on the fidelity error of the environmental qubit quantum gates.

[0194] The fourth determination unit 1508 is configured to determine the fidelity of the two-qubit quantum gates based on the frequency of the environmental qubit quantum gates.

[0195] It should be noted here that the above first determination unit 1502, second determination unit 1504, third determination unit 1506, and fourth determination unit 1508 correspond to steps S402 to S408 in Embodiment 1. The four units have the same implementation examples and application scenarios as the corresponding steps, but are not limited to the content disclosed in the above Embodiment 1. It should be noted that the above units may be hardware components or software components stored in a memory (for example, memory 104) and processed by one or more processors (for example, processors 102a, 102b..., 102n), and the above units may also be part of the device and can run in the computer terminal 10 provided in Embodiment 1.

[0196] According to the embodiments of the present application, there is also provided a device for determining the fidelity of qubit quantum gates in the quantum chip for implementing the method for determining the fidelity of qubit quantum gates in the quantum chip as described above. Figure 5 as shown in the quantum chip for implementing the method for determining the fidelity of qubit quantum gates.

[0197] Figure 16Schematic diagram of another apparatus for determining the fidelity of qubit quantum gates in a quantum chip according to an embodiment of the present application, as Figure 16 shown, the apparatus 1600 for determining the fidelity of qubit quantum gates in the quantum chip may include: a first acquisition unit 1602, a fifth determination unit 1604, a sixth determination unit 1606, a seventh determination unit 1608, and an output unit 1610.

[0198] The first acquisition unit 1602 is configured to acquire, by invoking a first interface, environmental qubit quantum gates associated with two-qubit quantum gates in a quantum processor, where the first interface includes a first parameter, and the parameter value of the first parameter is the two-qubit quantum gate and the environmental qubit quantum gate, and the two-qubit quantum gate and the environmental qubit quantum gate interact with each other in the quantum processor.

[0199] The fifth determination unit 1604 is configured to determine the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate.

[0200] The sixth determination unit 1606 is configured to determine the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate.

[0201] The seventh determination unit 1608 is configured to determine the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate.

[0202] The output unit 1610 is configured to output the fidelity of the two-qubit quantum gate by invoking a second interface, where the second interface includes a second parameter, and the parameter value of the second parameter is the fidelity of the two-qubit quantum gate.

[0203] It should be noted here that the above-mentioned first acquisition unit 1602, fifth determination unit 1604, sixth determination unit 1606, seventh determination unit 1608, and output unit 1610 correspond to steps S502 to S510 in Embodiment 1. The functions of the five units are the same as those of the corresponding steps in terms of the implemented examples and application scenarios, but are not limited to the content disclosed in the above-mentioned Embodiment 1. It should be noted that the above units may be hardware components or software components stored in a memory (for example, memory 104) and processed by one or more processors (for example, processors 102a, 102b..., 102n), or the above units may also be part of the apparatus and can run in the computer terminal 10 provided in Embodiment 1.

[0204] According to an embodiment of the present application, there is also provided an apparatus for determining the fidelity of qubit quantum gates in a quantum chip for implementing the above Figure 7 method for determining the fidelity of qubit quantum gates in the quantum chip shown.

[0205] Figure 17Schematic diagram of another apparatus for determining the fidelity of qubit quantum gates in a quantum chip according to an embodiment of the present application, as Figure 17 shown, the apparatus 1700 for determining the fidelity of qubit quantum gates in the quantum chip may include: a second acquisition unit 1702, an eighth determination unit 1704, a ninth determination unit 1706, a tenth determination unit 1708, and a return unit 1710.

[0206] The second acquisition unit 1702 is configured to acquire, from a quantum platform, environmental qubit quantum gates in a quantum processor that are associated with two-qubit quantum gates, where the two-qubit quantum gates interact with the environmental qubit quantum gates in the quantum processor.

[0207] The eighth determination unit 1704 is configured to determine the fidelity error of the environmental qubit quantum gates based on the fidelity error of the two-qubit quantum gates.

[0208] The ninth determination unit 1706 is configured to determine the frequency of the environmental qubit quantum gates based on the fidelity error of the environmental qubit quantum gates.

[0209] The tenth determination unit 1708 is configured to determine the fidelity of the two-qubit quantum gates based on the frequency of the environmental qubit quantum gates.

[0210] The return unit 1710 is configured to return the fidelity of the two-qubit quantum gates to the quantum platform.

[0211] It should be noted here that the above-mentioned second acquisition unit 1702, eighth determination unit 1704, ninth determination unit 1706, tenth determination unit 1708, and return unit 1710 correspond to steps S702 to S710 in Embodiment 1. The functions of the four units are the same as those of the corresponding steps in terms of the implemented examples and application scenarios, but are not limited to the content disclosed in the above-mentioned Embodiment 1. It should be noted that the above-mentioned units may be hardware components or software components stored in a memory (for example, memory 104) and processed by one or more processors (for example, processors 102a, 102b..., 102n), or the above-mentioned units may also be part of the apparatus and run on the computer terminal 10 provided in Embodiment 1.

[0212] In the apparatus for determining the fidelity of qubit quantum gates in the quantum chip of this embodiment, considering the influence of the environmental qubit quantum gates associated with the two-qubit quantum gates in the quantum processor on the two-qubit quantum gates, the fidelity is redefined, and the fidelity error of the two-qubit quantum gates is decomposed into different environmental qubit quantum gates, providing guidance for the frequency selection of the environmental qubit quantum gates, so as to determine the fidelity that meets the conditions, achieving the technical effect of improving the accuracy of determining the fidelity of the two-qubit quantum gates and solving the technical problem of being unable to determine the fidelity of the two qubit quantum gates.

[0213] Embodiment 4

[0214] Embodiments of the present application may provide a computer terminal, which may be any computer terminal device in a group of computer terminals. Optionally, in this embodiment, the above computer terminal may also be replaced with a terminal device such as a mobile terminal.

[0215] Optionally, in this embodiment, the above computer terminal may be located in at least one of multiple network devices in a computer network.

[0216] In this embodiment, the above computer terminal may execute the program code of the following steps in the method for determining the fidelity of qubit quantum gates in a quantum chip of an application program: determining an environmental qubit quantum gate associated with a two-qubit quantum gate in a quantum processor, where the two-qubit quantum gate interacts with the environmental qubit quantum gate in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; and determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate.

[0217] Optionally, Figure 18 is a structural block diagram of a computer terminal according to an embodiment of the present application. As Figure 18 shown, the computer terminal A may include: one or more (only one is shown in the figure) processors 1802, a memory 1804, and a transmission device 1806.

[0218] Among them, the memory may be used to store software programs and modules, such as program instructions / modules corresponding to the method and device for determining the fidelity of qubit quantum gates in a quantum chip in an embodiment of the present application. The processor executes various functional applications and predictions by running the software programs and modules stored in the memory, that is, implements the method for determining the fidelity of qubit quantum gates described above. The memory may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memories. In some instances, the memory may further include a memory remotely set relative to the processor, and these remote memories may be connected to the computer terminal A through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0219] The processor can call the information and application programs stored in the memory through a transmission device to execute the following steps: determining the environmental qubit gates associated with two-qubit quantum gates in the quantum processor, where the two-qubit quantum gates interact with the environmental qubit gates in the quantum processor; determining the fidelity error of the environmental qubit gates based on the fidelity error of the two-qubit quantum gates; determining the frequency of the environmental qubit gates based on the fidelity error of the environmental qubit gates; determining the fidelity of the two-qubit quantum gates based on the frequency of the environmental qubit gates.

[0220] Optionally, the above processor can also execute the program code of the following steps: decomposing the fidelity error of the two-qubit quantum gates onto different environmental qubit gates to obtain the fidelity errors of different environmental qubit gates.

[0221] Optionally, the above processor can also execute the program code of the following steps: scanning the superconducting circuit of the quantum processor to obtain various parameters; respectively determining the frequencies of the environmental qubit gates corresponding to the fidelity errors of the environmental qubit gates based on the various parameters.

[0222] Optionally, the above processor can also execute the program code of the following steps: determining the frequencies of the environmental qubit gates and the coupler corresponding to the fidelity errors of the environmental qubit gates based on single-qubit parameters; determining the fidelity of the two-qubit quantum gates at the frequencies of the environmental qubit gates and the coupler.

[0223] Optionally, the above processor can also execute the program code of the following steps: determining the frequencies of the environmental qubit gates and the coupler corresponding to the fidelity errors of the environmental qubit gates based on the number of single-qubit states of the multi-qubit model; determining the fidelity corresponding to the frequencies of the environmental qubit gates and the coupler as the fidelity of the two-qubit quantum gates.

[0224] Optionally, the above processor can also execute the program code of the following steps: determining the true local extremum based on the offset local extremum; determining the frequency of the environmental qubit gates corresponding to the fidelity error of the environmental qubit gates based on the true local extremum; determining the fidelity corresponding to the frequency of the environmental qubit gates as the fidelity of the two-qubit quantum gates.

[0225] Optionally, the above processor can also execute the program code of the following steps: determining the evolution result of the quantum processor in the basis; determining the frequency of the environmental qubit gates corresponding to the fidelity error of the environmental qubit gates based on the evolution result, where the magnitude of the fidelity error of the environmental qubit gates is less than the magnitude threshold.

[0226] Optionally, the above-mentioned processor may also execute the program code of the following steps: determining the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate based on the waveform parameters.

[0227] Optionally, the above-mentioned processor may also execute the program code of the following steps: determining the leakage information of the quantum processor at the local maximum; determining the qubit state to which the environmental qubit quantum gate corresponding to the leakage information jumps, and determining the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate in the qubit state; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate, including: determining the fidelity corresponding to the frequency of the environmental qubit quantum gate as the fidelity of the two-qubit quantum gate.

[0228] As an optional example, the processor may call the information and application programs stored in the memory through the transmission device to execute the following steps: obtaining the environmental qubit quantum gate associated with the two-qubit quantum gate in the quantum processor by calling the first interface, where the first interface includes a first parameter, and the parameter value of the first parameter is the two-qubit quantum gate and the environmental qubit quantum gate, and the two-qubit quantum gate and the environmental qubit quantum gate interact in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate; outputting the fidelity of the two-qubit quantum gate by calling the second interface, where the second interface includes a second parameter, and the parameter value of the second parameter is the fidelity of the two-qubit quantum gate.

[0229] As an optional example, the processor may call the information and application programs stored in the memory through the transmission device to execute the following steps: obtaining the environmental qubit quantum gate associated with the two-qubit quantum gate in the quantum processor from the quantum platform, where the two-qubit quantum gate and the environmental qubit quantum gate interact in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate; returning the fidelity of the two-qubit quantum gate to the quantum platform.

[0230] The embodiment of the present application considers the influence of the environmental qubit quantum gate associated with the two-qubit quantum gate on the two-qubit quantum gate in the quantum processor, redefines the fidelity, decomposes the fidelity error of the two-qubit quantum gate onto different environmental qubit quantum gates, provides guidance for the frequency selection of the environmental qubit quantum gate, and then determines the fidelity that meets the conditions, achieving the technical effect of improving the accuracy of determining the fidelity of the two-qubit quantum gate and solving the technical problem of being unable to determine the fidelity of the two qubit quantum gates.

[0231] Those of ordinary skill in the art can understand that Figure 18 the structure shown is only schematic, and computer terminal A can also be a smart phone (such as, tablet computer, palm computer, and terminal devices such as Mobile Internet Devices (MID), PAD, etc.). Figure 18 It does not limit the structure of the above computer terminal A. For example, computer terminal A may further include more or fewer components than Figure 18 shown (such as network interface, display device, etc.), or have a different configuration from Figure 18 shown.

[0232] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing the relevant hardware of the terminal device through a program, and the program can be stored in a computer-readable storage medium. The storage medium may include: flash drive, Read-Only Memory (ROM), Random Access Memory (RAM), magnetic disk or optical disk, etc.

[0233] Embodiment 5

[0234] The embodiment of the present application also provides a computer-readable storage medium. Optionally, in this embodiment, the above computer-readable storage medium can be used to save the program code executed by the method for determining the fidelity of the qubit quantum gate in the quantum chip provided in the above Embodiment 1.

[0235] Optionally, in this embodiment, the above computer-readable storage medium can be located in any one of the computer terminals in the computer terminal group in the computer network, or in any one of the mobile terminals in the mobile terminal group.

[0236] Optionally, in this embodiment, the above computer-readable storage medium is set to store program code for performing the following steps: determining the environmental qubit quantum gate associated with the two-qubit quantum gate in the quantum processor, where the two-qubit quantum gate interacts with the environmental qubit quantum gate in the quantum processor; determining the fidelity error of the environmental qubit quantum gate based on the fidelity error of the two-qubit quantum gate; determining the frequency of the environmental qubit quantum gate based on the fidelity error of the environmental qubit quantum gate; determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit quantum gate.

[0237] Optionally, the above computer-readable storage medium can also execute the program code of the following steps: scanning the superconducting circuit of the quantum processor to obtain various parameters; respectively determining the frequency of the environmental qubit quantum gate corresponding to the fidelity error of the environmental qubit quantum gate based on the various parameters.

[0238] Optionally, the above computer-readable storage medium may also execute program code for the following steps: determining the frequencies of the environmental qubit quantum gates and the frequencies of the couplers corresponding to the fidelity errors of the environmental qubit quantum gates based on single-bit parameters; determining the fidelity of the two-bit quantum gates at the frequencies of the environmental qubit quantum gates and the couplers.

[0239] Optionally, the above computer-readable storage medium may also execute program code for the following steps: determining the frequencies of the environmental qubit quantum gates and the frequencies of the couplers corresponding to the fidelity errors of the environmental qubit quantum gates based on the number of single-bit states of the multi-bit model; determining the fidelity of the two-bit quantum gates as the fidelity corresponding to the frequencies of the environmental qubit quantum gates and the couplers.

[0240] Optionally, the above computer-readable storage medium may also execute program code for the following steps: determining the true local extremum based on the offset local extremum; determining the frequencies of the environmental qubit quantum gates corresponding to the fidelity errors of the environmental qubit quantum gates based on the true local extremum; determining the fidelity of the two-bit quantum gates as the fidelity corresponding to the frequencies of the environmental qubit quantum gates.

[0241] Optionally, the above computer-readable storage medium may also execute program code for the following steps: determining the evolution result of the quantum processor in the basis; determining the frequencies of the environmental qubit quantum gates corresponding to the fidelity errors of the environmental qubit quantum gates based on the evolution result, where the magnitude of the fidelity error of the environmental qubit quantum gates is less than the magnitude threshold.

[0242] Optionally, the above computer-readable storage medium may also execute program code for the following steps: determining the frequencies of the environmental qubit quantum gates corresponding to the fidelity errors of the environmental qubit quantum gates based on waveform parameters.

[0243] Optionally, the above computer-readable storage medium may also execute program code for the following steps: determining the leakage information of the quantum processor at the local maximum; determining the qubit state to which the environmental qubit quantum gate corresponding to the leakage information jumps, and determining the frequencies of the environmental qubit quantum gates corresponding to the fidelity errors of the qubit state; determining the fidelity of the two-bit quantum gates based on the frequencies of the environmental qubit quantum gates, including: determining the fidelity corresponding to the frequencies of the environmental qubit quantum gates as the fidelity of the two-bit quantum gates.

[0244] As an alternative example, a computer-readable storage medium is configured to store program code for performing the following steps: obtaining, by invoking a first interface, environmental qubit gates associated with two-qubit quantum gates in a quantum processor, where the first interface includes a first parameter, and the parameter value of the first parameter is the two-qubit quantum gates and the environmental qubit gates, and the two-qubit quantum gates and the environmental qubit gates interact with each other in the quantum processor; determining the fidelity error of the environmental qubit gates based on the fidelity error of the two-qubit quantum gates; determining the frequency of the environmental qubit gates based on the fidelity error of the environmental qubit gates; determining the fidelity of the two-qubit quantum gates based on the frequency of the environmental qubit gates; and outputting the fidelity of the two-qubit quantum gates by invoking a second interface, where the second interface includes a second parameter, and the parameter value of the second parameter is the fidelity of the two-qubit quantum gates.

[0245] As an alternative example, a computer-readable storage medium is configured to store program code for performing the following steps: obtaining, from a quantum platform, environmental qubit gates associated with two-qubit quantum gates in a quantum processor, where the two-qubit quantum gates and the environmental qubit gates interact with each other in the quantum processor; determining the fidelity error of the environmental qubit gates based on the fidelity error of the two-qubit quantum gates; determining the frequency of the environmental qubit gates based on the fidelity error of the environmental qubit gates; determining the fidelity of the two-qubit quantum gates based on the frequency of the environmental qubit gates; and returning the fidelity of the two-qubit quantum gates to the quantum platform.

[0246] The serial numbers of the embodiments of the present application above are only for description and do not represent the advantages or disadvantages of the embodiments.

[0247] In the above embodiments of the present application, the descriptions of the various embodiments have their own emphases. For parts not detailed in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

[0248] In several embodiments provided by the present application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of units or modules can be in electrical or other forms.

[0249] The unit described as a separation component may or may not be physically separated. The component displayed as a unit may or may not be a physical unit, that is, it may be located in one place or may be distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0250] In addition, each functional unit in various embodiments of the present application may be integrated into a processing unit, may exist physically separately for each unit, or two or more units may be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0251] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present application. The aforementioned storage medium includes: USB flash drives, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), mobile hard disks, magnetic disks, or optical discs, etc., which can store program codes.

[0252] The above are only the preferred embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A method for determining the fidelity of a qubit quantum gate in a quantum processor, characterized in that, comprising: Determining an environmental qubit gate associated with a two-qubit quantum gate in the quantum processor, wherein the two-qubit quantum gate and the environmental qubit gate interact with each other in the quantum processor; Determining the fidelity error of the environmental qubit gate based on the fidelity error of the two-qubit quantum gate; Determining the frequency of the environmental qubit gate based on the fidelity error of the environmental qubit gate; Determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit gate; wherein, determining the fidelity error of the environmental qubit gate based on the fidelity error of the two-qubit quantum gate includes: decomposing the fidelity error of the two-qubit quantum gate to different environmental qubit gates to obtain the fidelity errors of different environmental qubit gates; Determining the frequency of the environmental qubit gate based on the fidelity error of the environmental qubit gate includes: scanning the superconducting circuit of the quantum processor to obtain a variety of parameters, wherein the variety of parameters at least includes: single-qubit parameters, the number of single-qubit states in the multi-qubit model, offset local extrema, basis vectors; respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the variety of parameters.

2. The method according to claim 1, characterized in that, respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the variety of parameters includes: Determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate and the frequency of the coupler based on the single-qubit parameters; wherein, determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit gate includes: determining the fidelity of the two-qubit quantum gate at the frequency of the environmental qubit gate and the frequency of the coupler.

3. The method according to claim 1, characterized in that, respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the variety of parameters includes: Determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate and the frequency of the coupler based on the number of single-qubit states in the multi-qubit model; Determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit gate includes: Determining the fidelity corresponding to the frequency of the environmental qubit gate and the frequency of the coupler as the fidelity of the two-qubit quantum gate.

4. The method according to claim 1, characterized in that, respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the variety of parameters includes: Determining the true local extremum based on the offset local extremum; Determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the true local extremum; Determining the fidelity of the two-qubit quantum gate based on the frequency of the environmental qubit gate includes: Determine the fidelity corresponding to the frequency of the environmental qubit gate as the fidelity of the two-qubit gate.

5. The method according to claim 1, wherein, respectively based on the multiple parameters, determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate includes: Determine the evolution result of the quantum processor in the basis; Based on the evolution result, determine the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate, wherein the magnitude of the fidelity error of the environmental qubit gate is less than the magnitude threshold.

6. The method according to claim 5, wherein, the multiple parameters include waveform parameters, and the waveform parameters are the maximum points determined based on the evolution result. Among them, respectively based on the multiple parameters, determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate includes: Based on the waveform parameters, determine the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate.

7. The method according to claim 5, wherein, the multiple parameters include the local maximum of the evolution result. Among them, respectively based on the multiple parameters, determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate includes: Determine the leakage information of the quantum processor at the local maximum; Determine the qubit state that the environmental qubit gate jumps to corresponding to the leakage information, and determine the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate in the qubit state; Based on the frequency of the environmental qubit gate, determining the fidelity of the two-qubit gate includes: Determine the fidelity corresponding to the frequency of the environmental qubit gate as the fidelity of the two-qubit gate.

8. The method according to any one of claims 1 to 7, wherein, the quantum processor includes inductively coupled fluxonium type qubits, or the quantum processor includes transmon type qubits.

9. A method for determining the fidelity of a qubit gate in a quantum processor, wherein, includes: Obtain the environmental qubit gate associated with the two-qubit gate in the quantum processor by calling the first interface. Among them, the first interface includes a first parameter, and the parameter value of the first parameter is the two-qubit gate and the environmental qubit gate, and the two-qubit gate and the environmental qubit gate interact with each other in the quantum processor; Based on the fidelity error of the two-qubit gate, determine the fidelity error of the environmental qubit gate; Based on the fidelity error of the environmental qubit gate, determine the frequency of the environmental qubit gate; Based on the frequency of the environmental qubit gate, determine the fidelity of the two-qubit gate; Output the fidelity of the two-qubit gate by calling the second interface. Among them, the second interface includes a second parameter, and the parameter value of the second parameter is the fidelity of the two-qubit gate; Among them, determining the fidelity error of the environmental qubit gate based on the fidelity error of the two-qubit gate includes: decomposing the fidelity error of the two-qubit gate onto different environmental qubit gates to obtain the fidelity errors of different environmental qubit gates; Determining the frequency of the environmental qubit gate based on the fidelity error of the environmental qubit gate includes: scanning the superconducting circuit of the quantum processor to obtain a variety of parameters, where the variety of parameters at least includes: single-qubit parameters, the number of single-qubit states in the multi-qubit model, offset local extrema, and basis vectors; respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the variety of parameters.

10. A method for determining the fidelity of qubit gates in a quantum processor, Characterized in that, Obtain an environmental qubit gate associated with a two-qubit gate in a quantum processor from a quantum platform, where the two-qubit gate and the environmental qubit gate interact with each other in the quantum processor; Determine the fidelity error of the environmental qubit gate based on the fidelity error of the two-qubit gate; Determine the frequency of the environmental qubit gate based on the fidelity error of the environmental qubit gate; Determine the fidelity of the two-qubit gate based on the frequency of the environmental qubit gate; Return the fidelity of the two-qubit gate to the quantum platform; Among them, determining the fidelity error of the environmental qubit gate based on the fidelity error of the two-qubit gate includes: decomposing the fidelity error of the two-qubit gate onto different environmental qubit gates to obtain the fidelity errors of different environmental qubit gates; Determining the frequency of the environmental qubit gate based on the fidelity error of the environmental qubit gate includes: scanning the superconducting circuit of the quantum processor to obtain a variety of parameters, where the variety of parameters at least includes: single-qubit parameters, the number of single-qubit states in the multi-qubit model, offset local extrema, and basis vectors; respectively determining the frequency of the environmental qubit gate corresponding to the fidelity error of the environmental qubit gate based on the variety of parameters.

11. A computer-readable storage medium, Characterized in that, The computer-readable storage medium includes a stored program, where when the program is run by a processor, it controls the device where the computer-readable storage medium is located to execute the method according to any one of claims 1 to 10.

12. A processor, Characterized in that, The processor is used to run a program, where when the program is run by the processor, it executes the method according to any one of claims 1 to 10.

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