CN-122021954-A - Quantum bit working frequency determining method on quantum processor and quantum computer

CN122021954ACN 122021954 ACN122021954 ACN 122021954ACN-122021954-A

Abstract

The application discloses a method for determining the working frequency of a qubit on a quantum processor and a quantum computer, and belongs to the technical field of quantum computing. The method comprises the steps of obtaining a topological structure diagram of a quantum processor, determining a quantum bit at the central position of the topological structure diagram, sequentially selecting target working frequencies of matching corresponding relations from allocable working frequencies of the quantum bits according to a frequency constraint model of each quantum bit according to the sequence of distances between other quantum bits and the quantum bit at the central position, determining the quantum bit with the allocable working frequency of the quantum bit and the corresponding relation which are not matched, taking the quantum bit as the central position, constructing a first sub-topological structure diagram from the topological structure diagram, and returning the sequence of distances between other quantum bits and the quantum bit at the central position, so as to redetermine the target working frequency of the quantum bit in the first sub-topological structure diagram. The application improves the utilization rate of the quantum bit on the quantum processor.

Inventors

KONG WEICHENG
Request for anonymity

Assignees

本源量子计算科技（合肥）股份有限公司

Dates

Publication Date: 20260512
Application Date: 20241030

Claims (10)

1. A method for characterizing the operating frequency of a qubit on a quantum processor, comprising: Obtaining a topological structure diagram of a quantum processor, and determining a quantum bit at the central position of the topological structure diagram, wherein the relative position of each quantum bit on the topological structure diagram corresponds to the physical structure of the quantum processor, and each quantum bit comprises a plurality of allocable working frequencies; Selecting target working frequencies of matching corresponding relations from the allocable working frequencies according to the sequence of the distances between other qubits and the qubit at the central position and according to a frequency constraint model of each qubit until all the qubits are selected, wherein the frequency constraint model is used for representing the corresponding relations between the XY crosstalk and residual ZZ coupling between each qubit and adjacent qubits and the working frequencies; And constructing a first sub-topology structure diagram from the topology structure diagram by taking the quantum bit as a central position, and returning to the step of determining the target working frequency of the quantum bit in the first sub-topology structure diagram according to the sequence of the distances between other quantum bits and the quantum bit at the central position.
2. The method of claim 1, wherein after determining to construct a first sub-topology structure from the topology structure map centered on a current qubit, the method further comprises: and clearing the determined target working frequency of other qubits in the first sub-topology structure diagram.
3. The method of claim 1, wherein obtaining a topology map of a quantum processor and determining a qubit for a central location of the topology map comprises: obtaining a topological structure diagram of a quantum processor; splitting the topology structure diagram into a plurality of second sub-topology structure diagrams; And determining a qubit of the central position of the second topological structure diagram.
4. The method of claim 1, wherein prior to obtaining a topology map of a quantum processor and determining a qubit for a central location of the topology map, the method further comprises: Presetting an initial working frequency range of each qubit of a topological structure diagram, wherein the initial working frequency range comprises a plurality of frequency initial values; Setting the working frequency of the qubit as the frequency initial value, and calibrating the logic gate parameters of the qubit for each qubit according to a directed acyclic graph, wherein the directed acyclic graph comprises a plurality of node graphs formed by the qubit and the performance parameters of a resonant cavity coupled and connected with the qubit; And executing a random reference test on the calibrated logic gate parameters to obtain the frequency initial value of the fidelity of the quantum state of the quantum bit within a preset threshold as the working frequency to be distributed of the quantum bit, wherein the random reference test is used for testing the corresponding relation between the fidelity of the quantum state of the quantum bit and the applied logic gate.
5. The method of claim 4, wherein performing a random reference test on the calibrated logic gate parameters to obtain a frequency initial value of the fidelity of the quantum state of the qubit within a preset threshold as the operating frequency of the qubit to be allocated, comprises: traversing a driving signal applied to the qubit so that the working frequency of the qubit corresponds to each frequency initial value of the initial working frequency range; When the working frequency of the qubit is each frequency initial value, a logic gate combination and an inverse logic gate are applied to the qubit, wherein the logic gate combination comprises a plurality of single-quantum logic gates which are used for regulating and controlling the quantum state of the qubit from an initial state to a target state, and the inverse logic gate is used for regulating and controlling the quantum state of the qubit from the target state to the initial state; measuring the fidelity of the quantum state of the qubit as an initial state; When the fidelity is within the preset threshold, determining the initial frequency value as the working frequency to be distributed; and when the fidelity is not within the preset threshold, discarding the corresponding frequency initial value.
6. The method of claim 1, wherein the method further comprises: presetting the number of times of redetermining the target working frequency of the qubit; And stopping the operation of redefining the target operating frequency after the number of times of redefining the target operating frequency of the qubit exceeds a preset value.
7. The method of claim 1, wherein the frequency constraint model comprises: |f i -f j |≥δ A1 ; f i -f j -α j |≥δ A2 ; f i -f j |<δ H1 ; Wherein f i is the allocable operating frequency of qubit i, f j is the target operating frequency of qubit j adjacent to the qubit, δ A1 is a first threshold set, α j is the non-harmonic size of qubit j, δ A2 is a second threshold set, g ik is the value of the residual ZZ coupling between the qubit and diagonal qubit k, f k is the target operating frequency of the diagonal qubit k, δ Z1 is a third threshold set, and the diagonal qubit is a qubit having a diagonal relationship with the qubit i on the topology.
8. A device for characterizing the operating frequency of a qubit on a quantum processor, comprising: The device comprises an acquisition module, a quantum processor and a control module, wherein the acquisition module is used for acquiring a topological structure diagram of the quantum processor, the relative position of each quantum bit on the topological structure diagram corresponds to the physical structure of the quantum processor, and each quantum bit comprises a plurality of allocable working frequencies; The device comprises a first determining module, a second determining module and a third determining module, wherein the first determining module is used for determining the quantum bit at the central position of the topological structure diagram, sequentially selecting a target working frequency of a matching corresponding relation from the allocable working frequencies of the quantum bit according to the distance sequence of other quantum bits and the quantum bit at the central position and according to a frequency constraint model of each quantum bit until all the quantum bits are selected; The second determining module is used for determining the quantum bit with the non-matched allocable working frequency and the corresponding relation of the quantum bit, taking the quantum bit as a central position, constructing a first sub-topology structure diagram from the topology structure diagram, returning to the step of determining the target working frequency from the allocable working frequency of each quantum bit in sequence according to the distance sequence of the quantum bit at the central position and other quantum bits and the frequency constraint model, and re-determining the target working frequency of the quantum bit in the first sub-topology structure diagram.
9. A quantum computer comprising the device for determining the operating frequency of a qubit on a quantum processor according to claim 8, or the method for determining the operating frequency of a qubit on a quantum processor according to any one of claims 1 to 7.
10. A readable storage medium having stored thereon a computer program, which when executed by a processor is capable of implementing the method of determining the operating frequency of a qubit on a quantum processor as claimed in any one of claims 1to 7.

Description

Quantum bit working frequency determining method on quantum processor and quantum computer Technical Field The application relates to the technical field of quantum computing, in particular to a method for determining the working frequency of a quantum bit on a quantum processor and a quantum computer. Background Quantum computation and quantum information are a cross subject for realizing computation and information processing tasks based on the principle of quantum mechanics, and have very close connection with subjects such as quantum physics, computer science, informatics and the like. There has been a rapid development in the last two decades. Quantum computer-based quantum algorithms in factorization, unstructured search, etc. scenarios exhibit far beyond the performance of existing classical computer-based algorithms, and this direction is expected to be beyond the existing computing power. Since quantum computing has the potential to solve certain problems far beyond the development of classical computer performance, in order to realize quantum computers, it is necessary to obtain a quantum processor containing a sufficient number and quality of qubits, and to enable extremely high fidelity quantum logic gate operation and readout of the qubits. Quantum processors are the core components of quantum computers, which are processors that perform quantum computation, and quantum computers are the traditional computers, which are the equivalent of CPUs. Before each quantum processor is formally used on line, each parameter of the qubit in the quantum processor needs to be tested and characterized. For each qubit in a quantum processor, it is desirable to implement as fast a qubit logic gate as possible in order to be able to perform as many computations as possible within the finite lifetime of the qubit. In general, the execution completion time of a qubit logic gate is typically three to four orders of magnitude faster than the qubit lifetime. However, fast qubit logic gate operations may cause the qubit logic gate to malfunction when executed. There are many reasons for the logic gate error of the qubit, and crosstalk is a major influencing factor, such as signal crosstalk (XY crosstalk) on the driving lines of adjacent qubits, leakage crosstalk (residual ZZ coupling) of couplers between adjacent qubits, and the like. When each qubit in the quantum processor is at a proper working frequency, the interference influence can be effectively reduced. With the expansion of quantum processors, the number of qubits is increasing, and the working frequency distribution of a plurality of qubits on the quantum processor is difficult to realize on the premise of reducing XY crosstalk and residual ZZ coupling. It should be noted that the information disclosed in the background section of the present application is only for enhancement of understanding of the general background of the present application and should not be taken as an admission or any form of suggestion that this information forms the prior art already known to those skilled in the art. Disclosure of Invention The application aims to provide a method for determining the working frequency of a qubit on a quantum processor and a quantum computer, which are used for solving the problems that in the prior art, in order to reduce XY crosstalk and residual ZZ coupling, the working frequency distribution difficulty of a plurality of qubits on the quantum processor is large and difficult to realize, and not only can the influence of the XY crosstalk and the residual ZZ coupling be reduced, but also the utilization rate of the qubits on the quantum processor is improved. In order to solve the technical problems, the technical scheme of the application comprises the following steps: The first aspect of the present application provides a method for characterizing a qubit operating frequency on a quantum processor, comprising: Obtaining a topological structure diagram of a quantum processor, and determining a quantum bit at the central position of the topological structure diagram, wherein the relative position of each quantum bit on the topological structure diagram corresponds to the physical structure of the quantum processor, and each quantum bit comprises a plurality of allocable working frequencies; Selecting target working frequencies of matching corresponding relations from the allocable working frequencies according to the sequence of the distances between other qubits and the qubit at the central position and according to a frequency constraint model of each qubit until all the qubits are selected, wherein the frequency constraint model is used for representing the corresponding relations between the XY crosstalk and residual ZZ coupling between each qubit and adjacent qubits and the working frequencies; And constructing a first sub-topology structure diagram from the topology structure diagram by taking the quantum bit as a central position, and retu