Superconducting quantum bit control signal calibration method and device, storage medium and electronic equipment
By measuring the transfer function matrix in situ, a calibration method was constructed to solve the problems of signal distortion and crosstalk in the control of superconducting qubits, achieving accurate calibration of multiple control signals and improving the reliability and signal quality of the superconducting quantum computing system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-28
- Publication Date
- 2026-03-20
AI Technical Summary
In superconducting quantum computing systems, signal distortion and crosstalk are complex and intertwined. Traditional calibration methods cannot meet the requirements of large-scale superconducting quantum bit control, resulting in quantum bit misoperation and affecting computational accuracy.
By measuring the transfer function matrix in situ, the response function and crosstalk function of the input control signal are determined, the transfer function matrix is constructed, and the calibrated input control signal is calculated to compensate for distortion and crosstalk, thereby achieving overall calibration of multiple control signals.
It enables precise measurement and calibration of minute signal distortions and crosstalk, improving the reliability and stability of superconducting quantum computing systems and enhancing signal quality and accuracy.
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Figure CN121707005A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of large-scale superconducting quantum computing, and more specifically, to a calibration method, apparatus, storage medium, and electronic device for superconducting quantum bit control signals. Background Technology
[0002] Multiplexed control signals often suffer from signal distortion and crosstalk during transmission. Signal distortion alters parameters such as amplitude and phase, affecting the receiver's response. Crosstalk, on the other hand, refers to interference between signals from different control lines, resulting in the receiver receiving a mixed signal—not the original, pure transmitted signal, but one infused with interference from other lines.
[0003] In superconducting quantum computing systems, qubits are highly dependent on the precision of the control signal. Even minute signal distortion or crosstalk can trigger qubit malfunctions, severely impacting the accuracy and reliability of quantum computing. The tailing effect caused by signal distortion leads to differences in the actual effect on the qubit when the same original waveform is output at different times, thus compromising the repeatability of quantum operations. Meanwhile, crosstalk causes the same quantum operation to exhibit different effects under conditions of parallel operation and non-parallel operation. In the control scenarios of large-scale superconducting qubits, signal distortion and crosstalk problems exhibit significant complexity. They not only coexist but are also intertwined and coupled; the crosstalk signal itself becomes distorted, and the distorted signal also generates crosstalk.
[0004] However, the inventors of this application have discovered that traditional calibration methods typically treat signal distortion and crosstalk as independent problems, and their effectiveness relies on the assumption that distortion and crosstalk do not affect each other. This assumption contradicts reality, making it difficult for traditional methods to meet the requirements of large-scale superconducting quantum bit control.
[0005] The content of the background section is merely technology known to the public and does not necessarily represent existing technology in the field. Summary of the Invention
[0006] According to one aspect of this application, a calibration method for a superconducting quantum bit control signal is provided. The method is based on in-situ measurement of the transfer function matrix. The calibration method includes: determining the response functions of all qubits of the input control signal to their respective input signals, and the response functions of all qubits to the input signals of the remaining qubits; determining the transfer function matrix based on the response functions of all qubits to their respective input signals and the response functions of all qubits to the input signals of the remaining qubits; determining the calibrated input control signal based on the transfer function matrix and the target input control signal; and calibrating the input control signal based on the calibrated input control signal.
[0007] According to another aspect of this application, a calibration device for a superconducting quantum bit control signal is also provided. The calibration device includes a measurement module and a calibration module. The measurement module determines the response functions of all qubits to their respective input signals, and the response functions of all qubits to the input signals of the remaining qubits. The calibration module determines a transfer function matrix based on the response functions of all qubits to their respective input signals and the response functions of all qubits to the input signals of the remaining qubits. The calibration module determines a calibrated input control signal based on the transfer function matrix and the target input control signal. The calibration module calibrates the input control signal based on the calibrated input control signal.
[0008] According to another aspect of this application, this application also provides a non-volatile computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is capable of implementing the calibration method for superconducting quantum bit control signals as described above.
[0009] According to another aspect of this application, this application also provides an electronic device, including: one or more processors; and a storage device for storing one or more programs, which, when executed by the one or more processors, enable the one or more processors to implement the calibration method for superconducting quantum bit control signals as described above.
[0010] According to another aspect of this application, this application also provides a computer program product, comprising: a computer program stored on a computer-readable storage medium; the computer program includes program instructions that, when executed by a computer, cause the computer to perform the calibration method for superconducting quantum bit control signals as described above.
[0011] The calibration method provided in this application can calculate the transfer function matrix through in-situ measurement, enabling precise measurement and calibration of small distortions and crosstalk in the input control signal. This meets the stringent requirements of superconducting quantum bit control for signal accuracy and improves the reliability and stability of the superconducting quantum computing system.
[0012] This application can simultaneously perform overall calibration of distortion and crosstalk in multiple control signals. Compared with traditional methods that can only handle one of the problems (distortion or crosstalk) separately, it is more suitable for complex scenarios such as large-scale superconducting quantum bit control, and greatly improves the quality and accuracy of the signal. Attached Figure Description
[0013] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 A schematic diagram of the structure of a calibration device according to an embodiment of this application is shown; Figure 2 A schematic flowchart of a calibration method 1000 according to an embodiment of this application is shown; Figure 3 A flowchart illustrating step S100 according to an embodiment of this application is shown. Figure 4 A flowchart illustrating step S110 according to an embodiment of this application is shown. Figure 5 A flowchart illustrating step S113 according to an embodiment of this application is shown. Figure 6 A flowchart illustrating step S1131 according to an embodiment of this application is shown. Figure 7 A flowchart illustrating step S120 according to an embodiment of this application is shown; Figure 8 A flowchart illustrating step S121 according to an embodiment of this application is shown; Figure 9 A flowchart illustrating step S1214 according to an embodiment of this application is shown. Figure 10 A flowchart illustrating step S12141 according to an embodiment of this application is shown. Figure 11 A flowchart illustrating step S300 according to an embodiment of this application is shown; Figure 12a A schematic diagram of the spectrum of a first qubit in a first in-situ measurement according to an embodiment of the present application is shown. Figure 12b This diagram shows a test circuit schematic of a first pulse group according to an embodiment of the present application; Figure 12cThis diagram shows a test circuit diagram of applying a second square wave pulse and a first pulse group to a first qubit according to an embodiment of this application; Figure 13a A schematic diagram of the spectrum of the first and second qubits involved in a second in-situ measurement of the first qubit according to an embodiment of this application is shown. Figure 13b This diagram shows a test circuit schematic of a second pulse group according to an embodiment of the present application; Figure 13c This diagram illustrates a measurement circuit in which a fourth square wave pulse is applied to a first qubit and a second pulse group is applied to a second qubit according to an embodiment of this application.
[0015] Explanation of reference numerals in the attached figures: Calibration device 200; measurement module 210; calibration module 220. Detailed Implementation
[0016] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0017] See Figure 1 The calibration device 200 for superconducting quantum bit control signals provided in this application includes a measurement module 210 and a calibration module 220. The following describes the process in conjunction with... Figure 1 This application describes a calibration method 1000 for superconducting quantum bit control signals.
[0018] See Figure 2 The calibration method 1000 may include steps S100-S400.
[0019] In step S100, the measurement module 210 determines the response function of all qubits of the input control signal to their respective input signals, and the response function of all qubits to the input signals of the remaining qubits.
[0020] According to an example embodiment, the input control signal can be a signal that manipulates the state of a superconducting quantum bit. The input control signal can simultaneously manipulate the state of a large number of superconducting quantum bits.
[0021] The input control signal includes multiple input control sub-signals. Each input control sub-signal can correspond one-to-one with a qubit.
[0022] All qubits can be superconducting qubits manipulated by input control signals. The response function of a qubit to its respective input signal can be seen as the relationship between the control signal received by a qubit in situ and the input control sub-signal controlling the qubit itself.
[0023] The measurement module 210 can determine the response function of each quantum bit to its respective input signal through in-situ measurement.
[0024] For example, the first qubit can be one of all qubits. The measurement module can measure the response function of the first qubit to the input control sub-signal corresponding to the first qubit through in-situ measurement.
[0025] The remaining qubits can be the qubits remaining after removing their own qubits from the total number of qubits. The input control signal of one qubit will also affect the control signals of the remaining qubits. The response function of a qubit to the input signals of the remaining qubits can be seen as the relationship between the control signal received by the qubit in situ and the input control signals of the remaining qubits. The measurement module can determine the response function of each qubit to the input signal of a single qubit through in-situ measurement. The measurement module 210 can iterate through each qubit to determine the response function of all qubits to the input signals of the remaining qubits.
[0026] For example, for the first qubit, the remaining qubits can be the qubits remaining after removing the first qubit from the total number of qubits. The measurement module 210 can determine the response functions of the remaining qubits to the input signal of the first qubit through in-situ measurement.
[0027] In step S200, the calibration module 220 determines the transfer function matrix based on the response functions of all qubits to their respective input signals and the response functions of all qubits to the input signals of the remaining qubits.
[0028] The transfer function matrix can be a matrix consisting of the response functions of all qubits to their respective input signals, and the response functions of all qubits to the input signals of the remaining qubits. The transfer function matrix can be an n×n matrix, where n is the number of qubits in the total number of qubits.
[0029] The calibration module 220 can construct a transfer function matrix based on the response functions of all qubits to their respective input signals, and the response functions of all qubits to the input signals of the remaining qubits. The transfer function matrix can completely describe the signal transmission relationship between the various qubits.
[0030] In step S300, the calibration module 220 determines the calibrated input control signal based on the transfer function matrix and the target input control signal.
[0031] According to an example embodiment, the target input control signal can be the input control signal that the qubit is expected to receive. The target input control signal may experience distortion and crosstalk during transmission. The calibrated input control signal can be a calibration signal that compensates for the distortion and crosstalk during the transmission of the target input control signal.
[0032] For example, the calibration module 220 can calculate the inverse matrix of the transfer function matrix, and calculate the calibrated input control signal based on the product of the inverse matrix of the transfer function matrix and the target input control signal.
[0033] In step S400, the calibration module 220 calibrates the input control signal according to the calibrated input control signal.
[0034] According to the example embodiment, the calibration module 220 can send the calibrated input control signal to the signal generating device. After transmission, the signal reaching all qubits can approximate the target input control signal, enabling all qubits to complete subsequent superconducting quantum computation.
[0035] Through the above embodiments, the technical solution of this application can determine the response functions of all qubits of the input control signal to their respective input signals, and the response functions of all qubits to the input signals of the remaining qubits. The technical solution of this application determines the transfer function matrix using the response functions of all qubits to their respective input signals and the response functions of all qubits to the input signals of the remaining qubits. The technical solution of this application determines the calibrated input control signal using the transfer function matrix and the target input control signal. The technical solution of this application calibrates the input control signal using the calibrated input control signal.
[0036] The calibration method provided in this application can obtain the transfer function matrix through in-situ measurement, enabling precise measurement and calibration of small distortions and crosstalk in the input control signal. This meets the stringent requirements of superconducting quantum bit control for signal accuracy and improves the reliability and stability of the superconducting quantum computing system.
[0037] This application can simultaneously perform overall calibration of distortion and crosstalk in multiple control signals. Compared with traditional methods that are only applicable to cases where multiple distortions and crosstalk are independent, this method is more suitable for complex scenarios such as large-scale superconducting quantum bit control, greatly improving the quality and accuracy of the signal.
[0038] Optionally, see Figure 3 Step S100 may include steps S110-S130.
[0039] In step S110, the measurement module 210 performs a first in-situ measurement on the first qubit to determine the response function of the first qubit to the input signal of the first qubit.
[0040] According to an example embodiment, the first qubit can be one of all qubits. The first in-situ measurement can be an in-situ measurement of the response function of the qubit to its own input signal.
[0041] The first in-situ measurement may include determining a first optimal bias voltage and a first flux-sensitive bias voltage for the first qubit; placing the first qubit at the first optimal bias voltage and applying a first pulse group to the first qubit to determine the correspondence between the phase of the first qubit and the amplitude of a first square wave pulse, wherein the first pulse group includes at least a first square wave pulse, the amplitude of the first square wave pulse being a first preset range, the first preset range being determined based on the first flux-sensitive bias voltage; and repeatedly applying a second square wave pulse and the first pulse group sequentially to the first qubit until the tail amplitude of the second square wave pulse meets the first preset condition to determine... The phase-time correspondence of the first qubit is determined, where the amplitude of the first square wave pulse is the first flux-sensitive bias voltage. Based on the phase-time correspondence of the first qubit and the amplitude of the first square wave pulse, and the phase-time correspondence of the first qubit, the true amplitude-time correspondence of the first square wave pulse under the influence of the tail signal of the second square wave pulse is determined. Based on the true amplitude-time correspondence of the first square wave pulse and the first flux-sensitive bias voltage, the tail signal of the second square wave pulse is determined. Based on the tail signal of the second square wave pulse, the response function of the first qubit to the input signal is determined.
[0042] In step S120, the measurement module 210 performs a second in-situ measurement on the remaining qubits traversing the first qubit to determine the response functions of the remaining qubits to the input signal of the first qubit.
[0043] According to an example embodiment, the second in-situ measurement can be an in-situ measurement of the response function of the remaining qubits to the qubit input signal.
[0044] For example, the measurement module 210 can determine the response function of the second qubit to the input signal of the first qubit through a second in-situ measurement. The second in-situ measurement may include: a step of determining the response function of the second qubit to the input signal of the first qubit; and a step of traversing the remaining qubits to determine the response function of the second qubit to the input signal of the first qubit, so as to determine the response functions of the remaining qubits to the input signal of the first qubit respectively.
[0045] The steps for determining the response function of the second qubit to the input signal of the first qubit include: determining a second optimal bias voltage and a second flux-sensitive bias voltage for the second qubit; determining a first idle bias voltage and a second idle bias voltage for the first qubit based on a preset frequency of the first qubit; placing the first qubit at the first idle bias voltage and the second qubit at the second optimal bias voltage, and applying a second pulse group to the second qubit to determine the correspondence between the phase of the second qubit and the amplitude of a third square wave pulse, wherein the second pulse group includes at least a third square wave pulse, the amplitude of which is a second preset range, the second preset range being determined based on the second flux-sensitive bias voltage; and repeating the sequential application of a fourth square wave pulse to the first qubit and the second qubit... A second pulse group is applied until the tail amplitude of the fourth square wave pulse meets a second preset condition to determine the phase-time correspondence of the second qubit. The amplitude of the fourth square wave pulse is the second idle bias voltage, and the amplitude of the third square wave pulse is the second flux-sensitive bias voltage. Based on the phase-time correspondence of the second qubit and the amplitude of the third square wave pulse, the true amplitude-time correspondence of the third square wave pulse under the influence of the tail signal of the fourth square wave pulse is determined. Based on the true amplitude-time correspondence of the third square wave pulse and the second flux-sensitive bias voltage, the tail signal of the fourth square wave pulse is determined. Based on the tail signal of the fourth square wave pulse, the response function of the second qubit to the input signal of the first qubit is determined. This process is repeated for the remaining qubits to determine the response functions of the second qubit to the input signal of the first qubit.
[0046] In step S130, the measurement module 210 traverses all qubits to determine the response function of each qubit to its respective input signal, and the response function of each qubit to the input signal of the remaining qubits.
[0047] According to the example embodiment, the measurement module 210 can traverse each qubit to determine the response function of each qubit to its own input signal, and the response functions of the remaining qubits to the input signal of each qubit.
[0048] Through the above embodiments, the technical solution of this application can determine the response function of the first qubit to the input signal of the first qubit by performing a first in-situ measurement on the first qubit. The technical solution of this application can determine the response functions of the remaining qubits to the input signal of the first qubit by performing a second in-situ measurement on the remaining qubits. The technical solution of this application can determine the response functions of all qubits to their respective input signals and the response functions of all qubits to the input signals of the remaining qubits by traversing all qubits.
[0049] The calibration method provided in this application can calculate the response function through in-situ measurement without removing the qubit from its environment.
[0050] Optionally, see Figure 4 Step S110 may include steps S111-S116.
[0051] In step S111, the measurement module 210 determines the first optimal bias voltage and the first flux-sensitive bias voltage of the first quantum bit.
[0052] According to the example embodiment, the sweet bias voltage is the flux bias corresponding to the point where the frequency of the qubit reaches its highest point. The flux-sensitive bias voltage (Fsbias) can be the flux bias corresponding to the point where the qubit frequency changes fastest with the flux bias.
[0053] The first optimal bias voltage (Sweet bias1) and the first flux-sensitive bias voltage (Fsbias1) are the two flux biases corresponding to the first qubit.
[0054] The measurement module 210 can scan the spectrum of the first qubit under different magnetic flux bias conditions through the spectrum measurement circuit and record the corresponding data, thereby plotting the spectrum variation curve with magnetic flux bias (e.g., Figure 12a As shown in the figure, the first optimal bias voltage and the first flux-sensitive bias voltage can be intuitively determined from the variation curve.
[0055] In step S112, the measurement module 210 places the first qubit at a first optimal bias voltage and applies a first pulse group to the first qubit to determine the correspondence between the phase of the first qubit and the amplitude of the first square wave pulse.
[0056] According to an example embodiment, the first pulse group can be a group of phase pulses accumulated by measuring the first qubit under the action of the first square wave pulse. The first pulse group may include a first pulse, a first square wave pulse, and a second pulse. The order of the three pulses in the first pulse group is fixed.
[0057] The first pulse can be The gate, the first pulse is used to initialize the first qubit. The first square wave pulse is about tens of nanoseconds long, and its amplitude is the first flux-sensitive bias voltage (Fsbias1). The first square wave pulse is used to induce an amplitude-dependent phase accumulation in the first qubit. The second pulse can be... The second pulse can help characterize the phase accumulated by the first qubit during the first square wave pulse.
[0058] The measurement module 210 can bias the first qubit at Sweet bias1 and then apply a first pulse, a first square wave pulse, and a second pulse to the first qubit in sequence.
[0059] In step S112, the amplitude of the first square wave pulse is a first preset range, which is determined based on the first magnetic flux-sensitive bias voltage. For example, the first preset range can be the amplitude range near the first magnetic flux-sensitive bias voltage (Fsbias1). In the control circuit of superconducting qubits, the amplitude of the pulse tail is usually less than 5%, so ±0.05 is chosen here.
[0060] The measurement module 210 can be centered on Fsbias1 within a small amplitude range (e.g. The amplitude of the first square wave pulse is scanned. For each scan amplitude value (Amp), the phase accumulated by the first qubit is precisely measured.
[0061] In this way, the measurement module 210 can acquire data within a set amplitude range. The correspondence between the phase of the first quantum bit and the amplitude of the first square wave pulse can be found in the measurement circuit. Figure 12b .
[0062] In step S113, the measurement module 210 repeatedly applies the second square wave pulse and the first pulse group to the first qubit in sequence until the tail amplitude of the second square wave pulse meets the first preset condition, so as to determine the phase-time correspondence of the first qubit.
[0063] According to the example embodiment, the second square wave pulse can be the target pulse for measuring the tail. The length of the second square wave pulse must exceed the total tail length caused by the distortion of the input control sub-signal of the first qubit to ensure the accuracy of subsequent measurements. The amplitude of the second square wave pulse can be preset with a step bias. After the second square wave pulse ends, the flux bias of the first qubit will return to Sweet bias1.
[0064] After the first qubit waits for a first preset time t1 in the Sweet bias1 state, the measurement module 210 applies the first pulse group to the first qubit again, thereby measuring and recording the phase accumulated by the first qubit under the first preset time t1. In step S113, the amplitude of the first square wave pulse is the first magnetic flux-sensitive bias voltage.
[0065] The measurement module 210 can repeatedly apply the second square wave pulse and the first pulse group to the first qubit, and the first preset time t1 waited during each repeated application of the second square wave pulse and the first pulse group is different, thereby obtaining the phase of the first qubit under different first preset times.
[0066] According to the example embodiment, the tail amplitude of the second square wave pulse can be the redundant signal amplitude caused by signal distortion, that is, the tail amplitude corresponding to the falling edge of the second square wave pulse. The first preset condition can be that when the phase of the first quantum bit measured by the measurement module 210 is converted into the tail amplitude of the second square wave pulse, the tail amplitude of the second square wave pulse is 0.
[0067] For example, see Figure 12c The measurement module 210 can repeatedly apply the second square wave pulse and the first pulse group to the first qubit until the tail amplitude of the measured second square wave pulse approaches 0. After obtaining the phase of the first qubit at different first preset times, the measurement module 210 can obtain the phase-time correspondence of the first qubit based on the phase of the first qubit at different first preset times. The measurement circuit can be as follows: Figure 12c As shown.
[0068] In step S114, the measurement module 210 determines the correspondence between the actual amplitude and time of the first square wave pulse under the influence of the trailing signal of the second square wave pulse, based on the correspondence between the phase of the first quantum bit and the amplitude of the first square wave pulse, and the correspondence between the phase of the first quantum bit and time.
[0069] According to the example embodiment, the measurement module 210 can calculate the inverse function of phase=f(amp) based on the correspondence between the phase of the first qubit and the amplitude of the first square wave pulse (e.g., phase=f(amp)) and the correspondence between the phase of the first qubit and time (e.g., phase=g(t)), thus obtaining... Substituting phase=g(t) into You can get it from the middle. This yields the correspondence between the true amplitude (Amp1) of the first square wave pulse and time under the influence of the trailing signal of the second square wave pulse.
[0070] In step S115, the measurement module 210 determines the trailing signal of the second square wave pulse based on the correspondence between the true amplitude and time of the first square wave pulse and the first magnetic flux sensitive bias voltage.
[0071] According to the example embodiment, the trailing signal of the second square wave pulse can be the trailing signal corresponding to the falling edge of the second square wave pulse. The trailing signal of the second square wave pulse is... The measurement module 210 can determine the relationship between the true amplitude (Amp1) of the first quantum bit and time, and the first flux-sensitive bias voltage (…). ), determine the trailing signal of the second square wave pulse ( The correspondence between time and time.
[0072] In step S116, the measurement module 210 determines the response function of the first quantum bit to the input signal based on the trailing signal of the second square wave pulse.
[0073] According to an example embodiment, the measurement module 210 can use a signal processing algorithm (e.g., Fourier transform, etc.) to determine the tail signal of the second square wave pulse ( The correspondence between time and the time is used to determine the self-response function of the first qubit. .
[0074] Through the above embodiments, the technical solution of this application can determine the response function of the first quantum bit to the input signal (i.e., the second square wave pulse) by performing a first in-situ measurement on the first quantum bit.
[0075] Optionally, see Figure 5 Step S113 may include steps S1131-S1132.
[0076] In step S1131, the measurement module 210 performs the step of determining the correspondence between the phase of the first qubit and the first preset time. (See also...) Figure 6 Step S1131 may include steps S11311-S11312.
[0077] In step S11311, after the measurement module 210 applies a second square wave pulse to the first quantum bit, it places the first quantum bit at a first optimal bias voltage.
[0078] In step S11312, the measurement module 210 waits for a first preset time and applies a first pulse group to the first qubit to determine the correspondence between the phase of the first qubit and the first preset time.
[0079] In step S1132, the measurement module 210 repeatedly executes the step of determining the correspondence between the phase of the first qubit and the first preset time. In each execution of the step of determining the correspondence between the phase of the first qubit and the first preset time, the first preset time is different until the tail amplitude of the second square wave pulse meets the first preset condition, so as to determine the correspondence between the phase of the first qubit and the time.
[0080] According to the example embodiment, the measurement module 210 can repeatedly apply the second square wave pulse and the first pulse group to the first qubit multiple times, and the first preset time t1 waited during each repeated application of the second square wave pulse and the first pulse group is different, thereby obtaining the phase of the first qubit under different first preset times.
[0081] For example, the measurement module 210 can repeatedly apply the second square wave pulse and the first pulse group to the first qubit until the tail amplitude of the measured second square wave pulse is close to 0. After obtaining the phase of the first qubit at different first preset times, the measurement module 210 can obtain the correspondence between the phase and time of the first qubit based on the phase of the first qubit at different first preset times.
[0082] Optionally, see Figure 7 Step S120 may include steps S121 and S122.
[0083] In step S121, the measurement module 210 performs the step of determining the response function of the second qubit to the input signal of the first qubit.
[0084] According to the example embodiment, the second qubit can be one of all qubits. The response function of the second qubit to the input signal of the first qubit can be the relationship between the control signal received by the second qubit in situ and the input control sub-signal of the first qubit.
[0085] See Figure 8 Step S121 may include steps S1211-S1217.
[0086] In step S1211, the measurement module 210 determines the second optimal bias voltage and the second flux-sensitive bias voltage of the second qubit.
[0087] According to the example embodiment, the second optimal bias voltage (Sweet bias2) and the second flux-sensitive bias voltage (Fsbias2) are the two flux biases corresponding to the second qubit.
[0088] The measurement module 210 can scan the spectrum of the second qubit under different magnetic flux bias conditions through the spectrum measurement circuit and record the corresponding data, thereby plotting the spectrum variation curve with magnetic flux bias (e.g., Figure 13a As shown in the figure, the second optimal bias voltage and the second flux-sensitive bias voltage can be intuitively determined from the variation curve.
[0089] In step S1212, the measurement module 210 determines the first idle bias voltage and the second idle bias voltage of the first quantum bit according to the preset frequency of the first quantum bit.
[0090] The first and second idle bias voltages can be two magnetic flux biases of the first qubit, determined according to the frequency of the first qubit. For example, such as... Figure 13a As shown, the first idle bias voltage can be a smaller voltage, and the second idle bias voltage can be a larger voltage.
[0091] When there is coupling between the first qubit and the second qubit, it is necessary to ensure that the frequency of the first qubit is significantly detuned from that of the second qubit in the sweetbias2 and fsbias2 states (the detuning is much greater than the coupling strength).
[0092] When there is no coupling between the first and second qubits, the frequency of the first qubit can be arbitrarily selected.
[0093] Whether there is coupling between the first and second qubits can be predetermined based on the type of quantum chip.
[0094] Corresponding to the frequency of the selected first qubit, find the two corresponding magnetic flux biases by referring to the spectrum of the first qubit, denoted as idlebias1 and idlebias2, respectively. Figure 13a As shown. Measurement module 210 can determine the flux bias with the smaller voltage between idlebias1 and idlebias2 as the first idle bias voltage.
[0095] In step S1213, the measurement module 210 places the first qubit at a first idle bias voltage and the second qubit at a second optimal bias voltage, and applies a second pulse group to the second qubit to determine the correspondence between the phase of the second qubit and the amplitude of the third wave pulse.
[0096] According to an example embodiment, the second pulse group can be a pulse group for measuring the phase accumulated by the second qubit under a third wave pulse. The second pulse group may include a third pulse, a third wave pulse, and a fourth pulse. The order of the three pulses in the second pulse group is fixed.
[0097] The third pulse is possible. The third pulse is used to initialize the second qubit. This third pulse is approximately tens of nanoseconds long and has an amplitude equal to the second flux-sensitive bias voltage (Fsbias2). It is used to induce amplitude-dependent phase accumulation in the second qubit. The fourth pulse can be... The fourth pulse can help characterize the phase accumulated by the second qubit during the third wave pulse.
[0098] The measurement module 210 can bias the first qubit at idlebias1 and then apply a third pulse, a third wave pulse, and a fourth pulse to the second qubit in sequence.
[0099] In step S1213, the amplitude of the third wave pulse is a second preset range, which is determined based on the second flux-sensitive bias voltage. For example, the second preset range can be the amplitude range near the second flux-sensitive bias voltage (Fsbias2). .
[0100] The measurement module 210 can be centered on Fsbias2 within a small amplitude range (e.g. The amplitude of the third wave pulse is scanned. For each scan amplitude value (Amp), the phase accumulated by the second qubit is precisely measured.
[0101] In this way, the measurement module 210 can acquire data within a set amplitude range. The correspondence between the phase of the second quantum bit and the amplitude of the third wave pulse can be found in the measurement circuit. Figure 13b .
[0102] In step S1214, the measurement module 210 repeatedly applies a fourth square wave pulse to the first qubit and a second pulse group to the second qubit until the tail amplitude of the fourth square wave pulse meets the second preset condition, so as to determine the phase-time correspondence of the second qubit.
[0103] According to the example embodiment, the fourth square wave pulse can be the target pulse for measuring the tail. The length of the fourth square wave pulse must exceed the total tail length received in situ by the second qubit due to crosstalk and distortion of the input control sub-signal of the first qubit, to ensure the accuracy of subsequent measurements. The amplitude of the fourth square wave pulse can be the second idle bias voltage (idlebias2). After the fourth square wave pulse ends, the flux bias of the first qubit will return to idlebias1.
[0104] Meanwhile, the measurement module 210 biases the second qubit at the second optimal bias voltage (Sweet bias2).
[0105] After the first qubit waits in the idlebias1 state for a second preset time t2, the measurement module 210 applies a second pulse group to the second qubit again, thereby measuring and recording the phase accumulated by the second qubit at the second preset time t2. In step S1214, the amplitude of the fourth square wave pulse is the second idle bias voltage, and the amplitude of the third square wave pulse is the second flux-sensitive bias voltage.
[0106] The measurement module 210 can repeatedly apply a fourth square wave pulse to the first qubit and apply a second pulse group to the second qubit. Furthermore, the second preset time t2 waited during each repeated application of the fourth square wave pulse and the second pulse group is different, thereby obtaining the phase of the second qubit under different second preset times.
[0107] According to the example embodiment, the tail amplitude of the fourth square wave pulse can be the redundant signal that ultimately acts on the second quantum bit through crosstalk and distortion of the falling edge of the fourth square wave pulse signal.
[0108] According to the example embodiment, the second preset condition can be that when the phase of the second quantum bit measured by the measurement module 210 is converted into the tail amplitude of the fourth square wave pulse, the tail amplitude of the fourth square wave pulse is 0.
[0109] For example, the measurement module 210 can repeatedly apply a fourth square wave pulse to the first qubit and a second pulse group to the second qubit until the tail amplitude of the measured fourth square wave pulse is close to 0. After obtaining the phase of the second qubit at different second preset times, the measurement module 210 can obtain the phase-time correspondence of the second qubit based on the phase of the second qubit at different second preset times. The measurement circuit can be as follows: Figure 13c As shown.
[0110] In step S1215, the measurement module 210 determines the correspondence between the actual amplitude and time of the third wave pulse under the influence of the trailing signal of the fourth wave pulse, based on the correspondence between the phase of the second quantum bit and the amplitude of the third wave pulse, and the correspondence between the phase of the second quantum bit and time.
[0111] According to the example embodiment, the measurement module 210 can calculate the inverse function of phase=f(amp) based on the correspondence between the phase of the second qubit and the amplitude of the third wave pulse (e.g., phase=f(amp)) and the correspondence between the phase of the second qubit and time (e.g., phase=g(t)), thus obtaining... Substituting phase=g(t) into You can get it from the middle. This yields the correspondence between the true amplitude (Amp2) of the third square wave pulse and time under the influence of the trailing signal of the fourth square wave pulse.
[0112] In step S1216, the measurement module 210 determines the trailing signal of the fourth square wave pulse based on the correspondence between the true amplitude and time of the third square wave pulse and the second magnetic flux sensitive bias voltage.
[0113] According to the example embodiment, the trailing signal of the fourth square wave pulse can be the redundant signal that ultimately acts on the second qubit through crosstalk and distortion of the falling edge of the fourth square wave pulse signal. The trailing signal of the fourth square wave pulse is... The measurement module 210 can determine the relationship between the true amplitude (Amp2) of the second quantum bit and time, and the second flux-sensitive bias voltage. ), determine the trailing signal of the fourth square wave pulse ( The correspondence between time and time.
[0114] In step S1217, the measurement module 210 determines the response function of the second qubit to the input signal of the first qubit based on the trailing signal of the fourth square wave pulse.
[0115] According to an example embodiment, the measurement module 210 can use a signal processing algorithm (e.g., Fourier transform, etc.) to determine the tail signal of the fourth square wave pulse ( The correspondence between time and the second qubit is used to determine the response function of the second qubit to the input signal of the first qubit. .
[0116] In step S122, the measurement module 210 iterates through the remaining qubits to determine the response function of the second qubit to the input signal of the first qubit, so as to determine the response functions of the remaining qubits to the input signal of the first qubit respectively.
[0117] According to the example embodiment, the measurement module 210 can iterate through the above-described steps S121 for the remaining qubits to determine the response functions of the remaining qubits to the input signal of the first qubit. . It is one of the remaining qubits.
[0118] Through the above embodiments, the technical solution of this application can determine the response function of the second quantum bit to the input signal (i.e., the fourth square wave pulse) of the first quantum bit by performing a second in-situ measurement on the first quantum bit.
[0119] Optionally, see Figure 9 Step S1214 may include steps S12141 and S12142.
[0120] In step S12141, the measurement module 210 performs the step of determining the correspondence between the phase of the second qubit and the second preset time.
[0121] See Figure 10 Step S12141 may include steps S121411 and S121412.
[0122] In step S121411, after the measurement module 210 applies a fourth square wave pulse to the first qubit, it sets the first qubit to the first idle bias voltage.
[0123] According to the example embodiment, the measurement module 210 can apply a fourth square wave pulse to the first qubit. The length of the fourth square wave pulse must exceed the total tail length caused by distortion and crosstalk of the input control sub-signal of the first qubit to ensure the accuracy of subsequent measurements. The amplitude of the fourth square wave pulse can be a second idle bias voltage (idlebias2). After the fourth square wave pulse ends, the flux bias of the first qubit will return to the first idle bias.
[0124] In step S121412, after applying the fourth square wave pulse, the measurement module 210 waits for a second preset time and applies a second pulse group to the second qubit to determine the correspondence between the phase of the second qubit and the second preset time.
[0125] According to the example embodiment, such as Figure 13b As shown, the measurement module 210 biases the second qubit at the second optimal bias voltage (Sweet bias2).
[0126] like Figure 13cAs shown, after the first qubit waits for a second preset time t2 in the first idle bias state, the measurement module 210 applies a second pulse group to the second qubit, thereby measuring and recording the phase accumulated by the second qubit under the second preset time t2.
[0127] In step S12142, the measurement module 210 repeatedly executes the step of determining the correspondence between the phase of the second qubit and the second preset time. In each execution of the step of determining the correspondence between the phase of the second qubit and the second preset time, the second preset time is different until the tail amplitude of the fourth square wave pulse meets the second preset condition, so as to determine the correspondence between the phase and time of the second qubit.
[0128] The measurement module 210 can repeatedly apply a fourth square wave pulse and a second pulse group to the second qubit. Furthermore, the second preset time t2 waited during each repeated application of the fourth square wave pulse and the second pulse group is different, thereby obtaining the phase of the second qubit under different second preset times.
[0129] For example, the measurement module 210 can repeatedly apply a fourth square wave pulse to the first qubit and a second pulse group to the second qubit until the tail amplitude of the measured fourth square wave pulse is close to 0. After obtaining the phase of the second qubit at different second preset times, the measurement module 210 can obtain the phase-time correspondence of the second qubit based on the phase of the second qubit at different second preset times.
[0130] According to the example embodiment, in step S130, the measurement module 210 can traverse all qubits to determine the response function of each qubit to its respective input signal. , and the response functions of all qubits to the input signals of the remaining qubits. . and These are two distinct qubits out of a total of qubits.
[0131] Let represent the response function of the i-th qubit to its own input signal; The response function of the j-th qubit to the input signal of the i-th qubit.
[0132] In step S200, the calibration module 220 can, according to all and all Construct the transfer function matrix Transfer function matrix It can be represented as: .
[0133] The calibration method provided in this application can determine the transfer function matrix through in-situ measurement and precise signal processing based on Fourier transform, and can achieve accurate measurement and calibration of small distortions and crosstalk of the target input control signal.
[0134] Optionally, see Figure 11 Step S300 may include steps S310 and S320.
[0135] In step S310, the calibration module 220 determines the inverse matrix of the transfer function matrix.
[0136] In step S320, the calibration module 220 determines the calibrated input control signal based on the product of the inverse matrix of the transfer function matrix and the target input control signal.
[0137] According to the example embodiment, the calibration module 220 can determine the calibration-post input control signal according to the following formula: ; in, This is the frequency domain representation of the calibrated input control signal for the nth qubit. The input control signal is used after calibration.
[0138] The frequency domain representation of the target input control signal for the nth qubit. Input control signals to the target. It is the inverse of the transfer function matrix.
[0139] Through the above embodiments, this application can determine the inverse matrix of the transfer function matrix. This application can determine the calibrated input control signal by multiplying the inverse matrix of the transfer function matrix by the target input control signal. The calibration method provided by this application can perform overall calibration of distortion and crosstalk in multiple control signals.
[0140] According to another aspect of this application, this application also provides a non-volatile computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is capable of implementing the calibration method for superconducting quantum bit control signals as described above.
[0141] According to another aspect of this application, this application also provides an electronic device, including: one or more processors; and a storage device for storing one or more programs, which, when executed by the one or more processors, enable the one or more processors to implement the calibration method for superconducting quantum bit control signals as described above.
[0142] According to another aspect of this application, this application also provides a computer program product, comprising: a computer program stored on a computer-readable storage medium; the computer program includes program instructions that, when executed by a computer, cause the computer to perform the calibration method for superconducting quantum bit control signals as described above.
[0143] Finally, it should be noted that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions of the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A calibration method for a superconducting quantum bit control signal, the method being based on in-situ measurement of the transfer function matrix, characterized in that, The calibration method includes: Determine the response functions of all qubits to their respective input signals, and the response functions of all qubits to the input signals of the remaining qubits; The transfer function matrix is determined based on the response functions of all the qubits to their respective input signals and the response functions of all the qubits to the input signals of the remaining qubits. The calibrated input control signal is determined based on the transfer function matrix and the target input control signal. The input control signal is calibrated based on the calibrated input control signal.
2. The calibration method according to claim 1, characterized in that, The determination of the response functions of all qubits to their respective input signals, and the response functions of all qubits to the input signals of the remaining qubits, includes: Perform a first in-situ measurement on the first qubit to determine the response function of the first qubit to the input signal of the first qubit; The remaining qubits are subjected to a second in-situ measurement that traverses the first qubit to determine the response functions of the remaining qubits to the input signal of the first qubit. The entire set of qubits is traversed to determine the response function of each qubit to its respective input signal, and the response function of each qubit to the input signal of the remaining qubits.
3. The calibration method according to claim 2, characterized in that, The step of performing a first in-situ measurement on the first qubit to determine the response function of the first qubit to the input signal of the first qubit includes: Determine the first optimal bias voltage and the first flux-sensitive bias voltage for the first quantum bit; The first qubit is placed at the first optimal bias voltage, and a first pulse group is applied to the first qubit to determine the correspondence between the phase of the first qubit and the amplitude of the first square wave pulse. The first pulse group includes at least the first square wave pulse, and the amplitude of the first square wave pulse is a first preset range. The first preset range is determined based on the first magnetic flux sensitive bias voltage. The first qubit is repeatedly and sequentially subjected to a second square wave pulse and the first pulse group until the tail amplitude of the second square wave pulse meets a first preset condition, so as to determine the phase-time correspondence of the first qubit, wherein the amplitude of the first square wave pulse is the first magnetic flux sensitive bias voltage. Based on the correspondence between the phase of the first qubit and the amplitude of the first square wave pulse, and the correspondence between the phase of the first qubit and time, the correspondence between the actual amplitude and time of the first square wave pulse under the influence of the trailing signal of the second square wave pulse is determined. Based on the correspondence between the true amplitude and time of the first square wave pulse and the first magnetic flux sensitive bias voltage, the trailing signal of the second square wave pulse is determined. The response function of the first qubit to the input signal is determined based on the trailing signal of the second square wave pulse.
4. The calibration method according to claim 3, characterized in that, The step of repeatedly applying a second square wave pulse and the first pulse group sequentially to the first qubit until the tail amplitude of the second square wave pulse meets a first preset condition to determine the phase-time correspondence of the first qubit includes: The step of determining the correspondence between the phase of the first qubit and the first preset time includes: After applying the second square wave pulse to the first qubit, the first qubit is placed at the first optimal bias voltage; Wait for a first preset time, then apply the first pulse group to the first qubit to determine the correspondence between the phase of the first qubit and the first preset time; The step of determining the correspondence between the phase of the first qubit and the first preset time is repeated, wherein the first preset time is different each time the step of determining the correspondence between the phase of the first qubit and the first preset time is executed, until the tail amplitude of the second square wave pulse satisfies the first preset condition, so as to determine the correspondence between the phase and time of the first qubit.
5. The calibration method according to claim 2, characterized in that, The second in-situ measurement of the remaining qubits through the first qubit to determine the response functions of the remaining qubits to the input signal of the first qubit includes: The steps for determining the response function of the second qubit to the input signal of the first qubit include: Determine the second optimal bias voltage and the second flux-sensitive bias voltage for the second quantum bit; Based on the preset frequency of the first quantum bit, determine the first idle bias voltage and the second idle bias voltage of the first quantum bit; The first qubit is placed at the first idle bias voltage, and the second qubit is placed at the second optimal bias voltage. A second pulse group is applied to the second qubit to determine the correspondence between the phase of the second qubit and the amplitude of the third wave pulse. The second pulse group includes at least the third wave pulse, and the amplitude of the third wave pulse is a second preset range. The second preset range is determined according to the second flux-sensitive bias voltage. The fourth square wave pulse is applied to the first qubit in sequence, and the second pulse group is applied to the second qubit in sequence, until the tail amplitude of the fourth square wave pulse meets the second preset condition, so as to determine the phase-time correspondence of the second qubit. The amplitude of the fourth square wave pulse is the second idle bias voltage, and the amplitude of the third square wave pulse is the second flux-sensitive bias voltage. Based on the correspondence between the phase of the second qubit and the amplitude of the third wave pulse, and the correspondence between the phase of the second qubit and time, the correspondence between the true amplitude and time of the third wave pulse under the influence of the trailing signal of the fourth wave pulse is determined. Based on the correspondence between the true amplitude and time of the third square wave pulse and the second magnetic flux sensitive bias voltage, the trailing signal of the fourth square wave pulse is determined. Based on the trailing signal of the fourth square wave pulse, determine the response function of the second qubit to the input signal of the first qubit; The remaining qubits are iterated through the step of determining the response function of the second qubit to the input signal of the first qubit, so as to determine the response functions of the remaining qubits to the input signal of the first qubit.
6. The calibration method according to claim 5, characterized in that, The repeated sequential application of the fourth square wave pulse to the first qubit and the application of the second pulse group to the second qubit until the tail amplitude of the fourth square wave pulse meets a second preset condition, in order to determine the phase-time correspondence of the second qubit, includes: The step of determining the correspondence between the phase of the second qubit and the second preset time includes: After the fourth square wave pulse is applied to the first qubit, the first qubit is set to the first idle bias voltage; After applying the fourth square wave pulse, wait for a second preset time, and then apply the second pulse group to the second qubit to determine the correspondence between the phase of the second qubit and the second preset time. The step of determining the correspondence between the phase of the second qubit and the second preset time is repeated, wherein the second preset time is different each time the step of determining the correspondence between the phase of the second qubit and the second preset time is executed, until the tail amplitude of the fourth square wave pulse satisfies the second preset condition, so as to determine the correspondence between the phase and time of the second qubit.
7. The calibration method according to claim 1, characterized in that, The step of determining the calibrated input control signal based on the transfer function matrix and the target input control signal includes: Determine the inverse of the transfer function matrix; The calibrated input control signal is determined by multiplying the inverse of the transfer function matrix with the target input control signal.
8. A calibration device for superconducting quantum bit control signals, characterized in that, The calibration device includes: The measurement module determines the response function of all qubits to their respective input signals, as well as the response function of all qubits to the input signals of the remaining qubits. The calibration module determines the transfer function matrix based on the response functions of all qubits to their respective input signals and the response functions of all qubits to the input signals of the remaining qubits. The calibration module determines the calibrated input control signal based on the transfer function matrix and the target input control signal. The calibration module calibrates the input control signal based on the calibrated input control signal.
9. A non-volatile computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the calibration method for the superconducting quantum bit control signal as described in any one of claims 1-7.
10. An electronic device, characterized in that, include: One or more processors; Storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the calibration method for the superconducting quantum bit control signal as described in any one of claims 1-7.