Method and apparatus for generating a qubit frequency control signal, and quantum computer

Abstract

The application discloses a quantum bit frequency control signal generation method, device and quantum computer. The quantum bit frequency control signal generation method is used for outputting a frequency control signal to a magnetic flux regulation circuit of a quantum bit. The method comprises the following steps: measuring a pulse distortion waveform output by a quantum control system to the magnetic flux regulation circuit of the quantum bit; wherein the pulse distortion waveform is a waveform after a control waveform is distorted when the control waveform is output by the quantum control system; performing filtering processing on waveform data of the pulse distortion waveform by using a digital filter and outputting filtered target waveform data; and outputting a target control signal to the magnetic flux regulation circuit according to the target waveform data. According to the application, a digital filter of a corresponding parameter can be determined by only one distortion measurement for each output channel, so that distortion measurement and calibration are avoided for each control signal that needs to be output, and the quantum computing efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of quantum computing, and in particular to a method, apparatus and quantum computer for generating a qubit frequency control signal. Background Technology

[0002] Quantum computing is a new computing paradigm that follows the laws of quantum mechanics to manipulate basic information units for computation. The basic information unit in classical computing is the classical bit, while in quantum computing it is the qubit. A classical bit can only be in one state, either 0 or 1, while a qubit, based on the superposition principle of quantum mechanics, can be in a superposition of multiple possible states. Therefore, the computational efficiency of quantum computing far exceeds that of classical computing.

[0003] The basic unit of quantum computing is the quantum processor, which integrates multiple qubits. These qubits are coupled to magnetic flux control circuitry, where signals, such as pulse signals, are used to control the frequency of the qubits. These pulse signals are typically output from a quantum control system (such as an integrated signal source or AWG, or Arbitrary Waveform Generator) to the magnetic flux control circuitry. However, the signal source or AWG integrates various amplifiers and operational amplifiers. Due to the influence of these components, the pulse signal output from the signal source or AWG undergoes waveform distortion. When this distortion is transmitted to the qubits through the magnetic flux control circuitry, the control precision of the qubits decreases.

[0004] In existing technologies, the distortion of each pulse signal output from the quantum control system to the magnetic flux control circuit is usually measured, and each pulse signal is compensated and calibrated based on the measured distortion. It is conceivable that when the number of qubits integrated on the quantum processor is large, and the qubits perform complex quantum computing tasks, each pulse signal output by the quantum control system needs to be calibrated for distortion individually, which is time-consuming and laborious, and directly affects the efficiency of quantum computing. Summary of the Invention

[0005] The purpose of this application is to provide a method, apparatus and quantum computer for generating qubit frequency control signals, so as to solve the problem of very high time cost of waveform calibration in the prior art and improve the efficiency of quantum computing.

[0006] To address the aforementioned technical problems, one aspect of this application provides a method for generating a qubit frequency control signal, used to output the frequency control signal to a qubit flux control circuit, comprising:

[0007] The pulse distortion waveform of the magnetic flux control circuit output from the quantum control system to the qubit is measured; wherein, the pulse distortion waveform is the waveform after distortion when the control waveform is output through the quantum control system.

[0008] A digital filter is used to filter the waveform data of the pulse distortion waveform and the filtered target waveform data is output.

[0009] Based on the target waveform data, a target control signal is output to the magnetic flux control circuit.

[0010] In the method for generating the qubit frequency control signal as described above, preferably, the pulse distortion waveform of the magnetic flux control circuit output by the quantum control system to the qubit specifically includes:

[0011] The first pulse signal is applied by the magnetic flux control circuit to make the frequency of the qubit located at the single-bit operating point.

[0012] A number of microwave signals are output to the qubit through a quantum state control circuit; wherein the microwave signals are used to perform single-bit gate operations on the qubit.

[0013] Apply each scan voltage within a preset voltage range to the flux control circuit to adjust the fidelity of the single-bit gate;

[0014] Obtain the scanning voltage corresponding to the maximum fidelity of the single-bit gate;

[0015] The pulse distortion waveform is obtained by compensating the first pulse signal based on the negative value of the scanning voltage.

[0016] The method for generating the quantum bit frequency control signal as described above, preferably, involves using a digital filter to filter the waveform data of the pulse distortion waveform and outputting the filtered target waveform data, specifically including:

[0017] The waveform data of the pulse distortion waveform is filtered using several parallel digital filters.

[0018] In the method for generating the quantum bit frequency control signal as described above, preferably, each of the digital filters is an Nth-order filter, and the order of each digital filter is less than the number of parallel digital filters.

[0019] In the method for generating the quantum bit frequency control signal as described above, preferably, the number of parallel outputs of the parallel digital filter is determined based on the operating clock frequency and the sampling rate of the digital-to-analog converter module; wherein, the digital-to-analog converter module is used to output the target control signal based on the target waveform data.

[0020] In the method for generating the quantum bit frequency control signal as described above, preferably, the step of using several parallel digital filters to filter the waveform data of the pulse distortion waveform specifically includes:

[0021] The waveform data of the pulse distortion waveform is filtered according to the processing coefficients of the digital filter; wherein the processing coefficients are determined based on the transfer function of the output data and input data of the digital filter.

[0022] In the method for generating the quantum bit frequency control signal as described above, preferably, the transfer function between the output data and the input data of the digital filter is:

[0023]

[0024] Where N is the order of the digital filter, L is the number of parallel outputs of the digital filter, y(Lk++-) where i = 1, ..., L; is the output data of the digital filter, y(Lk+-) where j = 0, ..., N-1; is the parallel output data of the digital filter in the previous clock cycle, f(Lk+N) is the input data of the parallel digital filter; A and B are the processing coefficients.

[0025] Another aspect of this application provides a device for generating a qubit frequency control signal, used to output the frequency control signal to a magnetic flux control circuit of the qubit, comprising:

[0026] A distortion measurement module is used to measure the pulse distortion waveform of the magnetic flux control circuit of a qubit; wherein, the pulse distortion waveform is the waveform after the control waveform is distorted by the magnetic flux control circuit;

[0027] A digital filtering module is used to filter the waveform data of the pulse distortion waveform and output the filtered target waveform data.

[0028] The signal output module is used to output a target control signal to the flux control circuit based on the target waveform data.

[0029] In the aforementioned quantum bit frequency control signal generation device, preferably, the digital filtering module is integrated inside the FPGA.

[0030] Another aspect of this application provides a quantum control system, including the calibration device for the manipulation waveform of the qubits described above.

[0031] Another aspect of this application provides a quantum computer, including the aforementioned quantum control system and quantum processor, wherein the quantum processor performs quantum computation based on a qubit frequency control signal output by the quantum control system.

[0032] Another aspect of this application provides a storage medium, characterized in that the storage medium stores a computer program, wherein the computer program is configured to execute any of the methods described above when running.

[0033] Another aspect of this application provides an electronic device including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform any of the methods described above.

[0034] Compared with existing technologies, the method for generating qubit frequency control signals provided in this application first measures the pulse distortion waveform of the magnetic flux control circuit output from the quantum control system to the qubit; then, it uses a digital filter to filter the waveform data of the pulse distortion waveform and outputs the filtered target waveform data; finally, it outputs the target control signal to the magnetic flux control circuit based on the target waveform data. This method measures the distortion effect of each output channel of the quantum control system and processes the pulse distortion waveform of each output channel using digital filters with different parameters. That is, each output channel only needs one distortion measurement to determine the corresponding digital filter parameters, and all subsequent control signals output by that output channel can be filtered using the same digital filter parameters. This avoids performing distortion measurement and calibration for every control signal that needs to be output, saving time and effort and improving quantum computing efficiency.

[0035] The quantum bit frequency control signal generation device and quantum computer provided in this application belong to the same concept as the quantum bit frequency control signal generation method, and therefore have the same beneficial effects, which will not be described in detail here. Attached Figure Description

[0036] Figure 1 A flowchart illustrating a method for generating a quantum bit frequency control signal, provided in an embodiment of this application;

[0037] Figure 2 A schematic diagram of pulse signal distortion provided in an embodiment of this application;

[0038] Figure 3 This application provides a schematic flowchart for measuring pulse distortion waveforms.

[0039] Figure 4 A schematic diagram of a 6th-order digital filter provided in an embodiment of this application;

[0040] Figure 5 This application provides a schematic diagram of a 2nd-order digital filter with parallel output after a 6th-order split, as shown in the embodiment of the present application. Figure 1 ;

[0041] Figure 6 A schematic diagram of a 3-parallel second-order digital filter is provided as an embodiment of this application;

[0042] Figure 7 This is a schematic diagram of the structure of a device for generating a quantum bit frequency control signal, provided in an embodiment of this application.

[0043] 10 - Distortion measurement module, 20 - Digital filtering module, 30 - Signal output module. Detailed Implementation

[0044] The specific embodiments of this application will be described in more detail below with reference to the schematic diagrams. The advantages and features of this application will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this application.

[0045] In the description of this application, it should be understood that the terms "center", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] Please refer to Figure 1 This application provides a method for generating a qubit frequency control signal, used to output the frequency control signal to a qubit flux control circuit, comprising the following steps:

[0048] Step S10: Measure the pulse distortion waveform of the magnetic flux control circuit output from the quantum control system to the qubit; wherein, the pulse distortion waveform is the waveform after distortion when the control waveform is output through the quantum control system.

[0049] As attached Figure 2 The diagram illustrates the distortion of a pulse waveform. The dashed line represents the square wave signal output from the signal source, while the solid line represents the distorted waveform output by the quantum control system. It can be observed that significant distortion occurs near the rising and falling edges of the signal. The pulse signal is used to control the operating frequency of the qubit. When the pulse signal is distorted, the operating frequency of the qubit deviates, directly affecting the control of the qubit's quantum state and consequently the accuracy of quantum computing.

[0050] The waveform distortion caused by each output channel of the quantum control system can be determined by measurement. During testing, a pulse signal of the target waveform is first output from the signal source, and the waveform distortion can be determined by directly measuring the pulse signal with a measuring instrument; alternatively, the waveform distortion can be indirectly measured by measuring the state changes of the qubits with a measuring instrument.

[0051] Step S20: Use a digital filter to filter the waveform data of the pulse distortion waveform and output the filtered target waveform data.

[0052] A digital filter is a filtering device composed of digital multipliers, adders, and delay units. It processes discrete input digital signals to modify the signal data. Pulse signals are typically output from signal sources, AWG (Analog-to-Glass) devices, or DACs, and the parameters of the output pulse signal are determined by the waveform data of the input pulse signal. (See attached...) Figure 2 The waveform data of the distorted waveform of the pulse signal shown can be processed into the waveform data of the target waveform through filtering by a digital filter, ensuring the control accuracy of the output target control signal on the qubit.

[0053] Step S30: Output the target control signal to the flux control circuit based on the target waveform data.

[0054] The target waveform data filtered by the digital filter is the waveform data of the target control signal to be transmitted to the qubit. The corresponding target control signal is generated based on the waveform data and output to the qubit through the magnetic flux control circuit.

[0055] In this embodiment, the pulse distortion waveform of the output channel of the quantum control system is first determined by measurement, and the waveform data of the pulse distortion waveform is processed by a digital filter in the quantum control system to obtain the required target waveform data. Then, the target control signal is output to the magnetic flux control circuit of the quantum bit according to the target waveform data.

[0056] Using the method of this embodiment, the digital filter with corresponding parameters for each output channel of the quantum control system can be determined by only one distortion measurement. All subsequent control signals output by the output channel can be filtered by the digital filter with the same parameters, avoiding distortion measurement and calibration for every control signal that needs to be output, saving time and effort, and improving the efficiency of quantum computing.

[0057] As attached Figure 3 As shown in this embodiment, it is necessary to first test the distortion caused by the circuit elements in the quantum control system. The measurement of the pulse distortion waveform of the magnetic flux control circuit output from the quantum control system to the qubit specifically includes the following steps:

[0058] Step S110: Apply a first pulse signal through the magnetic flux control circuit to make the frequency of the qubit located at the single-bit operating point.

[0059] Step S120: Output several microwave signals to the qubit through the quantum state control circuit; wherein the microwave signals are used to perform single-bit gate operations on the qubit.

[0060] The qubit is connected to a magnetic flux control circuit and a quantum state modulation circuit. The first pulse signal applied to the magnetic flux control circuit is used to adjust the operating frequency of the qubit so that it is at the single-bit operating point frequency. In addition, the microwave signal applied to the quantum state control circuit is used to adjust the quantum state of the qubit to perform single-bit gate operation.

[0061] It should be added that the first pulse signal applied to the flux control line is the pulse signal of the distortion effect to be measured. After the first pulse signal is distorted, it will change the frequency of the qubit, thereby affecting the modulation effect of the microwave signal on the qubit and affecting the fidelity of the single-qubit gate. In this embodiment, the single-qubit gate is the X-gate, which is the NOT gate. The function of the NOT gate is to control the state vector of the quantum state to rotate 180° around the X-axis of the Bloch sphere.

[0062] Step S130: Apply each scan voltage within a preset voltage range to the flux control circuit to adjust the fidelity of the single-bit gate.

[0063] For qubits, if no scanning voltage is applied, the distortion of the first pulse signal will alter the qubit's frequency due to the presence of the distortion voltage. With a scanning voltage applied, both the scanning voltage and the distortion voltage change the qubit's frequency. This change in qubit frequency alters the fidelity of the single-qubit gate. Theoretically, the fidelity of the single-qubit gate is maximized when the flux control circuit outputs no distortion voltage; that is, the fidelity reaches its maximum when the flux control circuit outputs zero distortion voltage. However, when the flux control circuit outputs distortion voltage, the fidelity of the single-qubit gate cannot reach its maximum. Therefore, applying a scanning voltage allows the scanning voltage to be superimposed on the distortion voltage, making the distortion voltage output by the flux control circuit zero.

[0064] Step S140: Obtain the scanning voltage corresponding to the maximum fidelity of the single-bit gate.

[0065] In addition to being coupled to flux control circuits and pulse control circuits, qubits are also coupled to signal readout circuits. The probability of a preset quantum state of the qubit can be read through the signal readout circuit. The probability of the preset quantum state is also the fidelity of a single-qubit gate. For example, when the probability of the quantum state |1> is the highest, the fidelity of the single-qubit gate is the highest.

[0066] Step S150: Compensate the first pulse signal based on the negative value of the scanning voltage to obtain the pulse distortion waveform.

[0067] When the fidelity of a single-bit gate is at its maximum, the corresponding scanning voltage and the distortion voltage have the same amplitude but are opposite to each other. The distortion voltage output by the flux control circuit is equivalent to zero. Therefore, the negative value of the scanning voltage is exactly the distortion voltage, which is then combined with the first pulse signal to obtain the pulse distortion waveform.

[0068] It should be noted that the above testing method obtains the pulse distortion waveform by testing the fidelity of a single-qubit gate of the qubit. This can be understood as indirectly measuring the pulse distortion waveform output by the quantum control system through the qubit. Alternatively, measurement can be performed directly. Specifically, a measuring device, such as an oscilloscope, is connected to the flux control circuit. The oscilloscope's measurement port is connected to the flux control circuit, and the quantum control system outputs a first pulse signal. The oscilloscope then directly measures the distorted pulse distortion waveform.

[0069] In comparison, direct measurement with an oscilloscope is simpler; however, due to the limitations of oscilloscope measurement accuracy, the accuracy of the measurement results is relatively low when the distortion voltage is small. Furthermore, the operating frequency of a qubit is highly sensitive to the distortion voltage; even a small distortion voltage can change the qubit's operating frequency, directly reducing the fidelity of the qubit executing a single-bit gate. Therefore, in the embodiments of this application, indirect measurement of pulse distortion waveforms using qubits is employed.

[0070] In this embodiment, the step of using digital filters to filter the waveform data of the pulse distortion waveform and outputting the filtered target waveform data specifically includes: using several parallel digital filters to filter the waveform data of the pulse distortion waveform. The target waveform data filtered by the digital filters needs to be sent to a digital-to-analog converter (DAC) module, which outputs a specific pulse signal. Therefore, the operating clock of the digital filters needs to match the sampling rate of the DAC.

[0071] As is well known, digital filters are filter devices integrated within FPGAs. Since the sampling rate of the DAC in this embodiment is relatively high, typically above 1 GHz, its sampling period is very short. If the operating clock frequency of the digital filter is matched to the sampling rate of the DAC, the digital filter will struggle to complete the operation within the sampling period. Therefore, it is necessary to reduce the operating clock frequency of the digital filter and use several parallel digital filters to process the waveform data. The number of sampling points is allocated to each parallel digital filter for filtering operations, and the parallel output results of the digital filters are summed to obtain the target waveform data, ensuring that the number of data points in the waveform data matches the high sampling rate of the DAC.

[0072] Furthermore, the parallelized digital filters are all low-order filters, generally no higher than order 2. For high-order digital filters, their order is reduced by splitting them. For example, a 6th-order digital filter is split into three parallel 2nd-order digital filters, and the outputs of the three 2nd-order digital filters are summed; each 2nd-order digital filter uses a parallel output method. For example, using an 8-parallel method, where the DAC sampling rate is 1.2Gsps, the operating clock of each low-order 2nd-order filter is equal to 1.2G / 8 = 125MHz.

[0073] Multiple digital filters are used in parallel to ensure synchronous reception and filtering of waveform data of pulse distortion waveforms, and the processed data is synchronously merged and output to the DAC. On the one hand, this reduces the operating clock frequency of the digital filters, ensuring the accuracy of the logic timing within the FPGA; on the other hand, it ensures the consistency of waveform data, ensuring high-precision processing of waveform data, and thus ensuring the accuracy of the target control signal output by the DAC.

[0074] Furthermore, in this embodiment, each of the digital filters is an N-order filter, and the order of each digital filter is less than the number of parallel digital filters; wherein, N is not greater than 2. When the digital filters perform filtering processing on the distorted waveform data, multi-order digital filters are used to improve the filtering effect on the waveform data. It is conceivable that the higher the order of the digital filters, the longer the filtering processing time for waveform processing will be, making it difficult to meet the timing requirements of FPGA. In this embodiment, the high-order digital filters are split into several low-order digital filters for parallel operation, and the system clock frequency is reduced to meet the DAC sampling rate requirements by using parallel output for each low-order data filter; and the order of the digital filters is less than the number of parallel digital filters, in this embodiment, the order of the digital filters is not greater than 2.

[0075] For example, in one embodiment, a 6th-order digital filter is split into three 2nd-order digital filters connected in parallel, and then each 2nd-order digital filter is output in parallel. By using a high number of parallel and low-order digital filters, not only can the filtering effect and accuracy requirements of the distorted waveform data be ensured, but also the data processing cycle of the digital filters can be matched with the sampling cycle of the DAC.

[0076] As described above, to reduce the operating clock frequency of the digital filters, several parallel digital filters are used. When determining the number of parallel digital filters, the number of parallel outputs of the parallel digital filters is determined based on the operating clock frequency and the sampling rate of the digital-to-analog converter (DAC). The DAC is used to output the target control signal based on the target waveform data. Specifically, the number of parallel outputs of the digital filters is equal to the quotient of the DAC's sampling rate and the digital filter's operating clock frequency; this ensures that the number of waveform data points after filtering by the parallel digital filters matches the number of sampling points of the DAC.

[0077] For example, using a 6-parallel output method, where the DAC sampling rate is 1.2Gsps, the operating clock of each low-order second-order filter is equal to 1.2G / 6 = 200MHz; using an 8-parallel output method, the operating clock of each low-order second-order filter is equal to 1.2G / 6 = 125MHz.

[0078] Digital filters include FIR filters and IIR filters. This embodiment mainly uses an IIR filter, which adopts a recursive structure with a feedback loop and consists of operations such as delay, multiplication by coefficients, and addition.

[0079] In one embodiment of this application, the step of using several parallel digital filters to filter the waveform data of the pulse distortion waveform specifically includes: filtering the waveform data of the pulse distortion waveform according to the processing coefficients of the digital filters; wherein, the processing coefficients are determined based on the transfer function of the output data and input data of the digital filters.

[0080] Specifically, for a digital filter, the pulse distortion waveform data is the input data, and the filtered waveform data is the output data. The processing coefficients of the digital filter directly affect the filtering effect on the waveform data. The transfer function of a digital filter can be expressed as:

[0081]

[0082] The waveform data of the pulse distortion waveform is represented by a sequence x(n). In the time domain, after filtering the waveform data through a digital filter, the output data is:

[0083] y(n)=-a1y(n-1)-a2y(n-2)-…-a N-1 y(n-N+1)+f(n)

[0084] Where, f(n) = b0x(n) + b1x(n-1) + b N-1 x(n-N+1).

[0085] Taking an L-parallel N-order digital filter as an example, its input data includes L parallel inputs, which can be represented as:

[0086] x(n)=x(Lk),x(Lk+1),x(Lk+2),…x(Lk+L-1)

[0087] The output of each order digital filter is represented as:

[0088] f(n)=f(Lk+N), f(Lk+N+1), f(Lk+N+2),…f(Lk+N+L-1)

[0089] By calculating the transfer function of the first N paths, and through look-ahead calculation, specifically performing L-N+m+1 and look-ahead operations on y(Lk+m), m = 0, 1, ..., N-1. During the look-ahead operation, the transfer function of the first N paths is:

[0090]

[0091] The output of the digital filter can be determined as follows:

[0092] y(Lk+L+m)=Q m0 y(Lk+N-1)+Q m1 y(Lk+-2)+

[0093] …+Q m，N-1 y(Lk)+P m0 f(Lk++)+P m，L-N+m f(Lk+N)

[0094] Based on the output formula of the digital filter above, the processing coefficients A and B are determined as follows:

[0095]

[0096]

[0097] Based on the processing coefficients A and B obtained above, the waveform data of the input pulse distortion waveform can be processed and the target waveform data can be output.

[0098] Based on the transfer function and processing coefficients of the digital filter described above, the transfer function between the output data and the input data of the digital filter is as follows:

[0099]

[0100] Where N is the order of the digital filter, L is the number of parallel outputs of the digital filter, y(Lk+L+Ni) is the output data of the digital filter, where i = 1, 2…L; y(Lk+Nj) is the parallel output data of the digital filter in the previous clock cycle, where j = 0,…N-1; f(Lk+N) is the input data of the parallel digital filter; A and B are the processing coefficients.

[0101] This embodiment takes a 2nd-order digital filter with 3 parallel outputs as an example, i.e., L=3, N=2. Combining the transfer function formula mentioned above, the transfer function of this 3-parallel 2nd-order digital filter can be determined as follows:

[0102]

[0103] The digital filter is subjected to second-order and third-order lead calculations, specifically as follows:

[0104] Secondary advancement:

[0105]

[0106] Three times ahead:

[0107]

[0108] For the first N paths of computation, the transfer function between the output and input data can be determined as follows:

[0109]

[0110] The processing coefficients of the parallel output of the second-order digital filter 3 mentioned above:

[0111] coefficient coefficient

[0112] As described above, the processing coefficients of the digital filter are used to process the waveform data of the pulse distortion waveform input to the input terminals of each parallel digital filter to obtain the target waveform data.

[0113] Combined with appendix Figure 4 Appendix Figure 5 and attached Figure 6 As shown in the embodiment of this application, a 6th-order digital filter is split into three 2nd-order digital filters, and a three-parallel processing process is illustrated.

[0114] As attached Figure 4 The 6th-order digital filter shown here, where IN is the input and OUT is the output, has the following transfer function:

[0115]

[0116] As attached Figure 5 The three second-order digital filters shown are for the purpose of... Figure 4 The schematic diagram of the decomposed 6th-order digital filter is shown below, and its transfer function is expressed as:

[0117]

[0118]

[0119]

[0120] Here, H1(z), H2(z), and H3(z) are the transfer functions of each of the decomposed second-order digital filters. Each second-order digital filter has one output, resulting in three outputs: OUT0, OUT1, and OUT2. The total output OUT is obtained by summing the three outputs. Each second-order digital filter can be expanded into a second-order three-parallel output filter; for example, expanding the second-order digital filter into three parallel outputs yields the expanded second-order three-parallel output filter. By expanding H1(z), H2(z), and H3(z) respectively to obtain the second-order three-parallel outputs of each filter and summing them, the filtered output is obtained, thus reducing the clock operating frequency.

[0121] Appendix Figure 6 The illustration is for the attachment Figure 5 The diagram illustrates the parallel output of three second-order digital filters after splitting. The transfer function of each parallel digital filter is f(x). For example, the three parallel filters of the first order are f1(3k+2), f1(3k+3), and f1(3k+4), and the three parallel filters of the second order are f2(3k+3) and f1(3k+4). The parallel outputs are y(3k), y(3k+1), and y(3k+2).

[0122] Combined with appendix Figure 4 Appendix Figure 5 and appendix Figure 6 The diagram illustrates the decomposition of high-order digital filters into low-order digital filters and their parallel processing. By combining this with the methods for determining the transfer functions mentioned above, the processing coefficients of the parallel digital filters can be determined. Then, based on the obtained processing coefficients, the input pulse distortion waveforms of each channel can be filtered to obtain the target waveform data.

[0123] As attached Figure 7As shown, based on the same application concept, this application embodiment also provides a qubit frequency control signal generation device for outputting a frequency control signal to a qubit flux control circuit, comprising: a distortion measurement module 10 for measuring the pulse distortion waveform of the qubit flux control circuit; wherein the pulse distortion waveform is the waveform after the control waveform is distorted by the flux control circuit; a digital filtering module 20 for filtering the waveform data of the pulse distortion waveform and outputting the filtered target waveform data; and a signal output module 30 for outputting a target control signal to the flux control circuit based on the target waveform data.

[0124] The distortion measurement module 10 measures the distortion of the output channel of the quantum control system to obtain the pulse distortion waveform, and the digital filtering module 20 performs filtering on the pulse distortion waveform to obtain the target waveform data. Finally, the corresponding target control signal is output through the signal output module 30. In this embodiment, the distortion measurement module 10 includes measuring instruments such as an oscilloscope and a spectrum analyzer, and the signal output module 30 uses a DAC.

[0125] In this embodiment, the digital filtering module is integrated inside the FPGA. The FPGA receives the waveform data of the pulse distortion waveform, sets up a digital filter module inside to filter the waveform data, and sends the processed target waveform data to the DAC, which outputs the corresponding target control signal.

[0126] Based on the same concept, embodiments of this application also provide a quantum control system, including the above-described calibration device for the manipulation waveform of qubits.

[0127] Based on the same concept, this application also provides a quantum computer, including the above-mentioned quantum control system and quantum processor, wherein the quantum processor performs quantum computing based on the qubit frequency control signal output by the quantum control system.

[0128] Based on the same concept, this application also provides a storage medium storing a computer program, wherein the computer program is configured to execute the above-described method for generating a quantum bit frequency control signal when running.

[0129] Specifically, in this embodiment, the storage medium may include, but is not limited to, USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks, and other media capable of storing computer programs.

[0130] Based on the same concept, embodiments of this application also provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor is configured to run the computer program to execute the above-described method for generating a quantum bit frequency control signal.

[0131] Specifically, the memory and processor can be connected via a data bus. Furthermore, the aforementioned electronic device may also include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0132] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," or "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0133] The above are merely preferred embodiments of this application and do not constitute any limitation on this application. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in this application without departing from the scope of the technical solutions of this application shall still fall within the protection scope of this application.

Claims

1. A method for generating a qubit frequency control signal, used to output the frequency control signal to a magnetic flux control circuit of the qubit, characterized in that, The method comprises: measuring a pulse distortion waveform of a magnetic flux control line output by a quantum control system to a quantum bit; wherein the pulse distortion waveform is a waveform of a control waveform after distortion when the control waveform is output by the quantum control system; filtering waveform data of the pulse distortion waveform using a plurality of parallel digital filters and outputting target waveform data after filtering; wherein the number of parallel outputs of the digital filters is determined according to a working clock frequency and a sampling rate of a digital-to-analog conversion module; the digital-to-analog conversion module outputs a target control signal to the magnetic flux control line according to the target waveform data.

2. The method of claim 1, wherein, The method of measuring a pulse distortion waveform of a magnetic flux control line output by a quantum control system to a quantum bit specifically comprises: applying a first pulse signal to the magnetic flux control line to make the frequency of the quantum bit at a single-bit operating point; outputting a plurality of microwave signals to the quantum bit through a quantum state control line; wherein the microwave signals are used for single-bit gate operation on the quantum bit; applying each scanning voltage in a preset voltage range to the magnetic flux control line to adjust the fidelity of the single-bit gate; obtaining a scanning voltage corresponding to the maximum value of the fidelity of the single-bit gate; compensating the first pulse signal according to the negative value of the scanning voltage to obtain the pulse distortion waveform.

3. The method of claim 1, wherein, Each of the digital filters is an N-order filter, and the order of each of the digital filters is less than the number of parallel outputs of the digital filters; wherein N is not greater than 2.

4. The method of claim 1, wherein, The method of filtering waveform data of the pulse distortion waveform using a plurality of parallel digital filters specifically comprises: filtering the waveform data of the pulse distortion waveform according to processing coefficients of the digital filters; wherein the processing coefficients are determined according to the transfer function of the output data and the input data of the digital filters.

5. The method of claim 4, wherein, The transfer function of the output data and the input data of the digital filters is: wherein N is the order of the digital filter, L is the number of parallel outputs of the digital filter, is the output data of the digital filter, wherein i = 1, 2, … L; is the output data of the digital filter at the previous clock, wherein j = 0, … N-1; is the input data of the digital filter in parallel; A, B are the processing coefficients.

6. A device for generating a qubit frequency control signal, used to output the frequency control signal to a magnetic flux control circuit of the qubit, characterized in that, The method comprises: an aberration measurement module for measuring a pulse distortion waveform of a magnetic flux control line of a quantum bit; wherein the pulse distortion waveform is a waveform of a control waveform after distortion when the control waveform passes through the magnetic flux control line; a digital filtering module for filtering waveform data of the pulse distortion waveform using a plurality of parallel digital filters and outputting target waveform data after filtering; wherein the number of parallel outputs of the digital filters is determined according to a working clock frequency and a sampling rate of a digital-to-analog conversion module; a digital-to-analog conversion module for outputting a target control signal to the magnetic flux control line according to the target waveform data.

7. The apparatus for generating a qubit frequency control signal of claim 6, wherein, The digital filtering module is integrated in the FPGA.

8. A quantum control system, characterized by, The calibration device for a control waveform of a quantum bit comprises the quantum control system of claim 6 or 7.

9. A quantum computer, characterized by The quantum control system and the quantum processor of claim 8, wherein the quantum processor performs quantum computing based on the quantum bit frequency control signal output by the quantum control system.

10. A storage medium, characterized by The storage medium stores a computer program, wherein the computer program is configured to execute the method of any one of claims 1 to 5 when running. 11.An electronic device comprising a memory and a processor, the electronic device characterized by, The memory stores a computer program, and the processor is configured to execute the computer program to execute the method of any one of claims 1 to 5.

Images