Multi-channel phase stability testing device and method based on high-bandwidth oscilloscope

Abstract

The invention discloses a multi-channel phase stability testing device based on a high-bandwidth oscilloscope, and aims to solve the problem that the requirement of pulse type output of quantum bit measurement and control signals cannot be met due to the fact that coherent measurement is carried out on continuous signals through a network analyzer in an existing method. The phase synchronization performance measurement among multi-channel superconducting quantum bit pulse type measurement and control signals is realized by adopting a reverse demodulo coherent calculation method.

Description

Technical Field

[0001] The present invention belongs to the technical field of superconducting quantum computing, and particularly relates to a multi-channel phase stability test device and method based on a high-bandwidth oscilloscope. Background Art

[0002] Due to the sensitivity of superconducting quantum processors to noise, there are high requirements for measurement and control signals. Among them, in order to implement two-qubit gate operations of superconducting qubits, multi-channel measurement and control signals of all qubits need to have a phase stability at the fs level.

[0003] The existing method is to perform coherent measurement on continuous signals using a network analyzer. However, the measurement and control signals of qubits are short pulse signals of about dozens of ns, which are different from the continuous output requirements of network analyzer measurements. At the same time, the network analyzer can only measure two continuous signals and cannot perform simultaneous measurement of multi-channel signals and measurement of pulsed signals. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-channel phase stability test device and method based on a high-bandwidth oscilloscope. By collecting multi-channel qubit measurement and control signals in the time domain using a high-bandwidth oscilloscope and through the method of inverse demodulation coherent calculation, the phase synchronization performance measurement between multi-channel pulsed measurement and control signals of superconducting qubits is realized.

[0005] To solve the above problems, the technical solution of the present invention is as follows:

[0006] A multi-channel phase stability test device based on a high-bandwidth oscilloscope includes a superconducting quantum processor measurement and control signal source module, a high-bandwidth oscilloscope, and a host computer;

[0007] The signal source module is used to generate at least three signals, where two signals are used as XY signals and the other is used as a Z signal. The frequencies of the XY signals are set to be different. If the XY signals are generated by the NCO + intermediate frequency mixing method, the NCO frequencies for generating the XY signals are different;

[0008] The Z signal and the XY signals are respectively connected to the corresponding channels of the high-bandwidth oscilloscope. The high-bandwidth oscilloscope triggers data acquisition based on the Z signal and sets the vertical resolution of each channel accordingly;

[0009] After the local oscillator signal with the same frequency and phase as the XY signals is envelope-modulated by the host computer, the acquired waveforms are demodulated to obtain a set of IQ values for each XY channel. After a preset duration of testing, multiple sets of IQ data for each XY channel are obtained and the testing is stopped. Further processing of the IQ data yields the statistical result of the phase difference between the two XY channels.

[0010] According to an embodiment of the present invention, the Z signal is connected to the first channel of the high-bandwidth oscilloscope, and the three XY signals are respectively connected to the second, third, and fourth channels of the high-bandwidth oscilloscope.

[0011] According to an embodiment of the present invention, the vertical resolution of the first channel of the high-bandwidth oscilloscope is set to 5 mV / grid, and the vertical resolutions of the second, third, and fourth channels are set such that the XY signals occupy 4 / 5 of the oscilloscope screen.

[0012] According to an embodiment of the present invention, the preset duration is 24 hours, and N groups of IQ data are obtained for each XY channel after the test ends.

[0013] According to an embodiment of the present invention, processing the IQ data includes converting the IQ data into a phase, calculating the phase difference between two of the XY channels, and statistically analyzing the phase difference to obtain the standard deviation of the phase jitter.

[0014] According to an embodiment of the present invention, further processing the IQ data includes:

[0015] For each IQ pair (I[n], Q[n]), where n represents the serial number of the data point, according to the following phase calculation formula, the phase value of each data point is calculated:

[0016] θ[n] = arctan(Q[n] / I[n])

[0017] Through the phase difference formula:

[0018] Δθ[n] = θ1[n] - θ2[n]

[0019] where θ1 and θ2 are the phase sequences of two XY channels respectively;

[0020] After calculating N phase differences, statistical analysis is performed on these phase difference data to evaluate the phase stability.

[0021] A multi-channel phase stability test method based on a high-bandwidth oscilloscope includes:

[0022] Writing control code, setting the superconducting quantum processor measurement and control XY signal and the superconducting quantum processor measurement and control Z signal to the trigger output mode, and setting the duration of each signal;

[0023] Connecting the Z signal to the first channel of the high-bandwidth oscilloscope, and connecting the three XY signals to the second, third, and fourth channels of the high-bandwidth oscilloscope respectively;

[0024] Set the high - bandwidth oscilloscope to trigger on the first channel, set the vertical resolution of the first channel to 5 mV / grid, and set the vertical resolutions of the second, third, and fourth channels so that the XY signal occupies 4 / 5 of the oscilloscope screen.

[0025] Each time a trigger occurs, data is collected once. After the local oscillator signal with the same frequency and phase as the XY signal is envelope - modulated by the host computer, the acquired waveform is demodulated to obtain a set of IQ values for each XY channel. After a preset duration of testing, multiple sets of IQ data for each XY channel are obtained and then the testing is stopped.

[0026] For each XY channel, the collected IQ data is converted into phase. The phase difference between two XY channels is obtained by taking the difference between the phase values of the two XY channels. N sets of data yield N phase differences, and the standard deviation of the phase jitter is calculated to evaluate the phase stability.

[0027] Due to the adoption of the above - mentioned technical solutions, the present invention has the following advantages and positive effects compared with the prior art:

[0028] In an embodiment of the present invention, a multi - channel pulse signal phase stability testing device based on a high - bandwidth oscilloscope, aiming at the requirement that the existing method using a network analyzer to perform coherent measurement on continuous signals cannot meet the pulsed output of quantum - bit measurement and control signals, collects multiple - path quantum - bit measurement and control signals in the time domain through a high - bandwidth oscilloscope, and realizes the measurement of the phase synchronization performance between multiple - path pulsed measurement and control signals of superconducting quantum bits through the method of reverse demodulation and coherent calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of a multi - channel phase stability testing device based on a high - bandwidth oscilloscope in an embodiment of the present invention;

[0030] Figure 2 It is a schematic diagram of the pulsed output of the phase stability test of superconducting quantum measurement and control signals in an embodiment of the present invention;

[0031] Figure 3 It is the display result of the data collected by the high - bandwidth oscilloscope in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following further elaborates in detail on a multi - channel phase stability testing device and method based on a high - bandwidth oscilloscope proposed by the present invention in combination with the accompanying drawings and specific embodiments. The advantages and features of the present invention will be clearer according to the following description and the claims.

[0033] For the superconducting quantum computing measurement and control equipment to be tested, there are generally XY signals and Z signals. The XY signals are used to perform gate operations on qubits, with a working frequency covering 3.5 GHz - 5.5 GHz. The Z signal is generally used for setting the working point of qubits, and the output is generally a signal around DC - 300 MHz. In order to test the phase stability between the measurement and control XY signals of superconducting qubits, this embodiment provides a multi-channel phase stability test device for a high-bandwidth oscilloscope to measure the phase synchronization performance between multiple pulsed measurement and control signals of superconducting qubits.

[0034] Please refer to Figure 1 , the multi-channel phase stability test device based on a high-bandwidth oscilloscope includes a signal source module (measurement and control module), a high-bandwidth oscilloscope, and a host computer; among them, the signal source module is used to generate at least three signals, two of which are used as XY signals, and the other is used as a Z signal. The frequencies of the XY signals are set to be different. If the XY signals are generated by the NCO + intermediate frequency mixing method, the NCO frequencies for generating the XY signals are different. Please refer to Figure 2 , there is no time interval relationship between triggers in the figure.

[0035] The Z signal and the XY signals are respectively connected to the corresponding channels of the high-bandwidth oscilloscope. The high-bandwidth oscilloscope triggers data acquisition based on the Z signal and makes corresponding settings for the vertical resolution of each channel. The host computer uses a local oscillator signal with the same frequency and phase as the XY signals, and after envelope modulation, demodulates the acquired waveforms to obtain a set of IQ values for each XY channel. After a preset duration of testing, multiple sets of IQ data for each XY channel are obtained and the testing is stopped. The preset duration can be 24 hours, and each XY channel obtains N sets of IQ data after the test. Further processing the IQ data yields the statistical result of the phase difference between the two XY channels.

[0036] Specifically, the Z signal is connected to the first channel of the high-bandwidth oscilloscope, and the three XY signals are respectively connected to the second, third, and fourth channels of the high-bandwidth oscilloscope. Compared with the scenario where only two channels can be tested in network analyzer testing, this embodiment can simultaneously measure 2 - 4 channels and can test pulsed waveforms.

[0037] In order to obtain accurate test results, the vertical resolution of the first channel of the high-bandwidth oscilloscope is set to 5 mV / grid, and the vertical resolutions of the second, third, and fourth channels are set to 15 mV / grid, so as to display the XY signals with full amplitude on the oscilloscope screen as much as possible, as Figure 3 shown.

[0038] After the local oscillator signal with the same frequency and phase as the XY signal is envelope - modulated by the host computer, the acquired waveform is demodulated to obtain a set of IQ values for each XY channel. After a preset duration of testing, multiple sets of IQ data for each XY channel are obtained and the testing is stopped. The preset duration can be 24 hours, and each XY channel obtains N sets of IQ data after the test. Processing the N sets of IQ data includes converting the IQ data into phase, calculating the phase difference between the two XY channels, and statistically analyzing the phase difference to obtain the standard deviation of phase jitter.

[0039] In the fields of communication and signal processing, IQ data is a commonly used signal representation. I represents the in - phase component, and Q represents the quadrature - phase component. These two components are orthogonal to each other and can be used to completely describe the characteristics of a signal. Generally speaking, IQ data is converted from the amplitude and phase information of a signal. By decomposing the signal onto the two orthogonal axes of I and Q, it is convenient to process the signal.

[0040] In signal processing, the complex - form IQ data can be expressed as C = I + jQ, where j is the imaginary unit. This complex number can be regarded as a vector starting from the origin, whose length represents the amplitude of the signal, and the angle between the vector and the I - axis is the phase of the signal.

[0041] The phase θ can be calculated through the arctangent function, and the formula is θ = arctan(Q / I). For example, assume there is an IQ data point with I = 3 and Q = 4, then the phase θ = arctan(4 / 3)≈53.13°. This phase value represents the angle of the signal relative to the reference direction (the positive direction of the I - axis) at that moment.

[0042] For the IQ data collected for each XY channel, it is necessary to ensure the accuracy of these data first. This requires correct settings of equipment such as oscilloscopes during the data acquisition stage, including the setting of vertical resolution, etc.

[0043] Once the IQ data sequence is obtained, the phase can be calculated for each data point. For each IQ pair (I[n], Q[n]), where n represents the serial number of the data point, according to the above - mentioned phase calculation formula θ[n]=arctan(Q[n] / I[n]), the phase value of each data point is calculated.

[0044] For example, in a test device, for the XY signals of Channel 2, a set of IQ data is collected. The I component is [3.2, 4.5, 2.1...], and the Q component is [1.8, 3.7, 0.5...]. Then for the first data point, the phase θ1 = arctan(1.8 / 3.2) ≈ 29.05°; for the second data point, θ2 = arctan(3.7 / 4.5) ≈ 40.36°, and so on, to obtain the phase sequence of all data points in the entire channel.

[0045] For two XY channels, after calculating their respective phase sequences, the phase difference can be calculated. The phase difference Δθ[n] = θ1[n] - θ2[n], where θ1 and θ2 are the phase sequences of the two XY channels respectively. After obtaining N phase difference values through calculation, statistical analysis can be performed on these phase difference data, such as calculating the standard deviation, so as to evaluate the phase stability.

[0046] When using the above multi-channel phase stability test device based on a high-bandwidth oscilloscope for testing, the following steps are included:

[0047] a. Write control code to set XY and Z to trigger output mode, with the XY and Z waveform durations being 20 ns, and the frequencies of the two XY channels being different. If the XY uses the NCO + intermediate-frequency mixing method, the NCO frequencies should also be different. As Figure 2 shown, note that there is no time relationship between the time intervals between triggers in the figure.

[0048] b. Connect the measurement and control Z output signal to Channel 1 of the oscilloscope, and connect the other three XY signals to Channels 2, 3, and 4 of the oscilloscope respectively;

[0049] c. Set the oscilloscope to trigger on Channel 1. For accurate testing, adjust the vertical resolution of Channel 1 to 5 mV / grid, and set Channels 2, 3, and 4 to 15 mV / grid. Try to display the XY signals within 4 / 5 of the space on the oscilloscope screen at full amplitude, as Figure 3 shown;

[0050] d. Collect data once for each trigger. After the local oscillator signal with the same frequency and phase is envelope-modulated by the host computer, the collected waveform is demodulated. Each XY channel obtains a set of IQ values. After 24 hours of collection, each XY channel obtains N sets of IQ data, and the test stops;

[0051] e. For each XY channel, convert the collected IQ data into phase, and subtract the phase values between the two XY channels to obtain the phase difference between the two XY channels. N phase differences are obtained from N sets of data, and the standard deviation of the phase jitter is obtained through statistics.

[0052] This method can test the phase relationship between microwave pulse signals required for superconducting qubit control. Compared with the scenario in the network analyzer test scheme where only two channels can be tested and the signals are required to be pulse signals, this method can simultaneously measure 2 - 4 channels, and the signals can be pulse signals, improving the test conditions and test efficiency.

[0053] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, provided that these changes fall within the scope of the claims of the present invention and its equivalent technologies, they still fall within the protection scope of the present invention.

Claims

1. A multi-channel phase stability test device based on a high-bandwidth oscilloscope, characterized in that, It includes a superconducting quantum measurement and control signal source module, a high-bandwidth oscilloscope, and a host computer; The signal source module is used to generate at least three signals, two of which are used as the superconducting quantum processor measurement and control XY signals, and the other is used as the superconducting quantum processor measurement and control Z signal. The frequencies of the XY signals are set to be different. If the XY signals are generated by the NCO + intermediate frequency mixing method, the NCO frequencies for generating the XY signals are different; The Z signal and the XY signals are respectively connected to the corresponding channels of the high-bandwidth oscilloscope. The high-bandwidth oscilloscope triggers data acquisition based on the Z signal and sets the vertical resolution of each channel accordingly, so that the XY signals fill 4 / 5 of the oscilloscope screen; After the local oscillator signal with the same frequency and phase as the XY signals is envelope-modulated by the host computer, the acquired waveforms are coherently demodulated to obtain a set of phase and amplitude for each XY channel. After a preset duration of testing, multiple sets of IQ data for each XY channel are obtained and the testing is stopped. Further, the IQ data is processed to obtain the statistical results of the phase difference and amplitude difference between the two XY channels.

2. The multi-channel phase stability test device based on a high-bandwidth oscilloscope according to claim 1, characterized in that The Z signal is connected to the first channel of the high-bandwidth oscilloscope, and the three XY signals are respectively connected to the second, third, and fourth channels of the high-bandwidth oscilloscope.

3. The multi-channel phase stability test device based on a high-bandwidth oscilloscope according to claim 2, characterized in that, The vertical resolution of the first channel of the high-bandwidth oscilloscope is set to 5 mV / grid, and the vertical resolutions of the second, third, and fourth channels are set so that the XY signals fill 4 / 5 of the oscilloscope screen.

4. The multi-channel phase stability test device based on a high-bandwidth oscilloscope according to claim 1, wherein The preset duration is 24 hours, and N sets of IQ data are obtained for each XY channel after the test ends.

5. The multi-channel phase stability test device based on a high-bandwidth oscilloscope according to claim 1, characterized in that, Processing the IQ data includes converting the IQ data into phase, calculating the phase difference between the two XY channels, and statistically analyzing the phase difference to obtain the standard deviation and peak-to-peak value of the phase jitter.

6. The multi-channel phase stability test device based on a high-bandwidth oscilloscope according to claim 5, characterized in that Further processing the IQ data includes: For each IQ pair (I[n], Q[n]), where n represents the serial number of the data point, according to the following phase calculation formula, the phase value of each data point is calculated: θ[n] = arctan(Q[n] / I[n]) Through the phase difference formula: Δθ[n] = θ1[n] - θ2[n] where θ1 and θ2 are the phase sequences of the two XY channels respectively; After calculating N phase differences, statistical analysis is performed on these phase difference data to evaluate the phase stability.

7. A multi-channel phase stability test method based on a high-bandwidth oscilloscope, characterized in that, It includes: Writing control codes, setting both the XY signals and the Z signal to the trigger output mode, and setting the duration of each signal; Connecting the Z signal to the first channel of the high-bandwidth oscilloscope, and connecting the three XY signals to the second, third, and fourth channels of the high-bandwidth oscilloscope respectively; Setting the high-bandwidth oscilloscope to be triggered by the first channel, setting the vertical resolution of the first channel to 5 mV / grid, and setting the vertical resolutions of the second, third, and fourth channels so that the XY signals fill 4 / 5 of the oscilloscope screen; Each time the acquisition is triggered, once the data is collected, the host computer uses the local oscillator signal with the same frequency and phase as the XY signal. After envelope modulation, the collected waveform is demodulated to obtain a set of IQ values for each XY channel. After a preset duration of testing, multiple sets of IQ data for each XY channel are obtained and then the testing is stopped; For each XY channel, the collected IQ data is converted into phase. The phase difference between two XY channels is obtained by taking the difference between the phase values of the two XY channels. N phase differences are obtained from N sets of data, and the standard deviation of the phase jitter is calculated to evaluate the phase stability.

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