CN-121998110-A - Quantum bit target working frequency determining method and device and quantum computer

CN121998110ACN 121998110 ACN121998110 ACN 121998110ACN-121998110-A

Abstract

The application discloses a method and a device for determining the working frequency of a qubit target and a quantum computer, and belongs to the technical field of quantum computing; the method comprises the steps of establishing a topological structure diagram of a quantum processor according to relative physical positions of all quantum bits on the quantum processor, traversing a plurality of frequency initial values preset for each quantum bit, executing random reference test on quantum logic gates applied to each quantum bit, determining the assignable working frequency of each quantum bit according to the fidelity of a quantum state obtained by the test, constructing a frequency constraint model of the target working frequency of each quantum bit, wherein the frequency constraint model is used for limiting the XY crosstalk and residual ZZ coupling between each quantum bit and adjacent quantum bits, and determining the target working frequency from the assignable working frequency of each quantum bit according to the topological structure diagram and the frequency constraint model. The target working frequency determined by the application can avoid the influence of XY crosstalk and residual ZZ coupling.

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: 20260508
Application Date: 20241030

Claims (10)

1. A method for determining a qubit target operating frequency, comprising: Establishing a corresponding topological structure diagram according to the relative physical position of each qubit on the quantum processor; Traversing a plurality of frequency initial values preset for each qubit, executing random reference test on a quantum logic gate applied to each qubit through traversing, and determining the assignable working frequency of each qubit according to the fidelity of a quantum state obtained by the test; Constructing a frequency constraint model of the target working frequency of each qubit, wherein the frequency constraint model is used for representing the corresponding relation between the XY crosstalk and residual ZZ coupling between each qubit and the adjacent qubit and the working frequency; And determining a target working frequency from the assignable working frequencies of each qubit according to the topological structure diagram and the frequency constraint model.
2. The method of claim 1, wherein traversing the preset number of initial frequency values for each qubit, performing a random reference test on a quantum logic gate applied to each qubit, and determining an assignable operating frequency for each of the qubits based on a fidelity of a quantum state obtained by the test, comprises: Presetting an initial working frequency range of each qubit, 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, and obtaining the frequency initial value of the fidelity of the quantum state of the quantum bit within a preset threshold value 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.
3. The method of claim 2, 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.
4. 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 a target qubit i, f j is the target operating frequency of a qubit j adjacent to the target qubit, δ A1 is a first set threshold, α j is the non-harmonic size of the qubit j, δ A2 is a second set threshold, g ik is the value of the residual ZZ coupling between the target qubit and a diagonal qubit k, f k is the target operating frequency of the diagonal qubit k, δ Z1 is a third set threshold, and the diagonal qubit is a qubit having a diagonal relationship with the target qubit i on the topology structure.
5. The method of claim 4, wherein determining a target operating frequency from the allocable operating frequencies of each of the qubits in accordance with the topology map, the frequency constraint model, comprises: Determining a qubit at the central position of the topological structure diagram as a basic qubit, and determining one of the allocable working frequencies of the basic qubit as a target working frequency; sequentially selecting the next quantum bit as a target quantum bit according to the sequence from small to large of the distance between each other quantum bit and the basic quantum bit; and selecting a frequency value conforming to the frequency constraint model from the allocable working frequencies of the target qubits as a target working frequency.
6. The method of claim 5, wherein selecting a frequency value from the allocable operating frequencies of the target qubit that meets the frequency constraint model as a target operating frequency comprises: Substituting the target working frequencies of all the determined qubits into the frequency constraint model as known parameters to obtain the target working frequency of the next target qubit.
7. The method of claim 6, wherein substituting the target operating frequencies of all the determined qubits as known parameters into the frequency constraint model to obtain the target operating frequency of the next target qubit comprises: And when the allocable working frequencies of the target qubits which conform to the frequency constraint model are a plurality of, selecting the allocable working frequency with the largest frequency value as the target working frequency.
8. A device for determining a target operating frequency of a qubit, comprising: the first modeling module is used for building a topological structure diagram of the quantum processor according to the relative physical positions of all the qubits on the quantum processor; The testing module is used for traversing a plurality of frequency initial values preset for each quantum bit, executing random reference test on a quantum logic gate applied to each quantum bit through traversing, and determining the allocable working frequency of each quantum bit according to the fidelity of a quantum state obtained by the test; the second modeling module is used for constructing a frequency constraint model of the target working frequency of each qubit, and the frequency constraint model is used for limiting the XY crosstalk and the residual ZZ coupling between each qubit and the adjacent qubit; And the determining module is used for determining a target working frequency from the allocable working frequencies of each qubit according to the topological structure diagram and the frequency constraint model.
9. A quantum computer comprising the device for determining a target operating frequency of a qubit according to claim 8, or the method for determining a target operating frequency of a qubit 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 a qubit target operating frequency according to any one of claims 1 to 7.

Description

Quantum bit target working frequency determining method and device and quantum computer Technical Field The present application relates to the field of quantum computing technologies, and in particular, to a method and an apparatus for determining a target operating frequency of a qubit, 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. 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 and a device for determining a target working frequency of a quantum bit and a quantum computer, wherein the determined target working frequency can enable the fidelity of a quantum logic gate applied to the quantum bit to be higher, and can avoid the influence of XY crosstalk and residual ZZ coupling. In order to solve the technical problems, the technical scheme of the application is as follows: the first aspect of the present application provides a method for determining a qubit target operating frequency, including: Establishing a corresponding topological structure diagram according to the relative physical position of each qubit on the quantum processor; Traversing a plurality of frequency initial values preset for each qubit, executing random reference test on a quantum logic gate applied to each qubit through traversing, and determining the assignable working frequency of each qubit according to the fidelity of a quantum state obtained by the test; Constructing a frequency constraint model of the target working frequency of each qubit, wherein the frequency constraint model is used for representing the corresponding relation between the XY crosstalk and residual ZZ coupling between each qubit and the adjacent qubit and the working frequency; And determining a target working frequency from the assignable working frequencies of each qubit according to the topological structure diagram and the frequency constraint model. The method as described above, optionally, comprises traversing a plurality of frequency initial values preset for each qubit, performing a random reference test on a quantum logic gate applied to each qubit, and determining an assignable operating frequency of each qubit according to the fidelity of a quantum state obtained by the test, including: Presetting an initial working frequency range of each qubit, 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 q