Method and device for optimizing signal of quantum signal link and quantum computer

Abstract

The invention discloses a method and device for optimizing signals of a quantum signal link and a quantum computer. The quantum signal link comprises a signal source, a high-pass filter and quantum bits on a quantum processing unit which are electrically connected in sequence through a signal transmission line. The signal source is used for outputting a pulse signal for regulating and controlling the frequency of the quantum bit. The method comprises the following steps: determining a target time constant representing the signal transmission characteristic of a quantum signal link according to the response condition of the frequency of the quantum bit to the pulse signal; determining a first pulse waveform according to the target time constant; wherein the first pulse waveform is used for compensating the distortion of the pulse signal after the pulse is ended; and determining an optimized signal of the quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized. According to the invention, the adjustment accuracy of the working frequency of the quantum bit is improved, and the de-coherence performance of the quantum bit is improved.

Description

Technical Field

[0001] The present application relates to the field of quantum computer technology, and in particular to a method and device for optimizing signals in a quantum signal link, and a quantum computer. Background Art

[0002] Quantum computing is expected to significantly accelerate computing tasks that are almost impossible to solve on traditional computers in the future. In the existing quantum computing physical system, there are quantum processing units used to perform computing tasks, and quantum computing measurement and control systems that control and measure the quantum processing units. The quantum computing measurement and control system is connected to the quantum processing unit through a signal transmission line.

[0003] The quantum processing unit integrates multiple quantum bits, each of which is coupled to a flux modulation circuit. A pulse signal is applied to the flux modulation circuit through a signal transmission circuit to adjust the operating frequency of each quantum bit. For the low-frequency noise existing on the flux modulation circuit, the prior art usually sets a filter in the signal transmission link between the signal source and the quantum bit to filter out the low-frequency noise.

[0004] However, the pulse signal for adjusting the working frequency of the quantum bit is generally a low-frequency signal, and the filtering characteristics of the filter will cause the waveform of the pulse signal to be distorted; for example, there will still be residual voltage on the flux modulation circuit at the end of the pulse time. Especially when multiple tests are performed and multiple pulse signals are applied continuously, the residual voltage will be superimposed, affecting the control effect of the next pulse signal, and thus affecting the accuracy of adjusting the working frequency of the quantum bit.

[0005] Therefore, how to filter out the low-frequency noise of the flux modulation circuit while ensuring the accuracy of adjusting the working frequency of the quantum bit has become an urgent problem to be solved in this field. Summary of the invention

[0006] The present application provides a signal optimization method, device and quantum computer for a quantum signal link, which solves the problem in the prior art that when a filter is used to filter out low-frequency noise of a flux modulation circuit, the pulse signal is distorted, which affects the accuracy of adjusting the working frequency of the quantum bit, thereby improving the accuracy of adjusting the working frequency of the quantum bit and further improving the decoherence performance of the quantum bit.

[0007] On one hand, the present application provides a method for optimizing a signal of a quantum signal link, wherein the quantum signal link comprises a signal source, a high-pass filter, and a quantum bit on a quantum processing unit which are electrically connected in sequence through a signal transmission line; the signal source is used to output a pulse signal for regulating the frequency of the quantum bit;

[0008] The method comprises:

[0009] Determining a target time constant characterizing a signal transmission characteristic of a quantum signal link according to a response of the frequency of the quantum bit to the pulse signal;

[0010] Determining a first pulse waveform according to the target time constant; wherein the first pulse waveform is used to compensate for the distortion of the pulse signal after the pulse ends;

[0011] The signal of the optimized quantum signal link is determined according to the first pulse waveform and the pulse signal waveform to be optimized.

[0012] In the above method, preferably, determining the target time constant characterizing the signal transmission characteristics of the quantum signal link according to the response of the frequency of the quantum bit to the pulse signal includes:

[0013] Determine a plurality of corresponding second pulse waveforms according to the pulse signal waveform to be optimized and a plurality of preset time constants within a first preset range; wherein the second pulse waveform is formed by splicing the first waveform and the second waveform according to the pulse time;

[0014] Outputting corresponding pulse signals to the quantum bits respectively according to a plurality of the second pulse waveforms;

[0015] performing a Ramsey experiment on the qubit during the duration of the second waveform to obtain a measurement frequency of the qubit;

[0016] The preset time constant when the measurement frequency is the same as the natural frequency of the quantum bit is determined as the target time constant.

[0017] The method as described above preferably further comprises, before determining the corresponding plurality of second pulse waveforms according to the pulse signal waveform to be optimized and the plurality of preset time constants within the first preset range:

[0018] Determine an initial compensation waveform according to the pulse signal waveform to be optimized and a plurality of preset time constants within a second preset range; wherein the initial compensation waveform is formed by splicing the first compensation waveform and the second compensation waveform according to the pulse time;

[0019] Outputting corresponding pulse signals to the quantum bits according to a plurality of the initial compensation waveforms;

[0020] Controlling the quantum state of the quantum bit to an excited state during the duration of the second compensation waveform;

[0021] measuring the probability that the quantum state of the quantum bit is an excited state after the pulse time of the pulse signal corresponding to the initial compensation waveform;

[0022] Determine a preset time constant when the probability that the quantum state of the quantum bit is an excited state is the maximum as an initial time constant;

[0023] The first preset range is determined according to the initial time constant.

[0024] In the above method, preferably, determining the first pulse waveform according to the target time constant comprises:

[0025] Determine that the corresponding relationship among the time constant, the distortion amplitude, the pulse amplitude and the pulse time is a first preset relationship; wherein the distortion amplitude is the amplitude of the distortion of the pulse signal waveform to be optimized after the pulse time ends due to the influence of the high-pass filter, and the pulse amplitude and the pulse time are waveform parameters of the first pulse waveform;

[0026] determining a target distortion amplitude according to the target time constant;

[0027] Determining a target pulse amplitude and a target pulse time of the first pulse waveform according to the target distortion amplitude, the target time constant and the first preset relationship;

[0028] The first pulse waveform is determined according to the target pulse amplitude and the target pulse time.

[0029] In the method described above, preferably, determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized includes:

[0030] splicing the pulse signal waveform to be optimized and the first pulse waveform according to the pulse time;

[0031] The spliced ​​pulse waveform is determined to be the pulse waveform of the signal of the optimized quantum signal link.

[0032] In the method described above, preferably, determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized includes:

[0033] Determining a second pulse waveform corresponding to the target time constant;

[0034] splicing the second pulse waveform and the first pulse waveform according to pulse time;

[0035] The spliced ​​pulse waveform is determined to be the pulse waveform of the signal of the optimized quantum signal link.

[0036] In the method described above, preferably, determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized includes:

[0037] determining at least two second pulse waveforms corresponding to the target time constant;

[0038] splicing at least two of the second pulse waveforms and the first pulse waveform according to pulse time;

[0039] The spliced ​​pulse waveform is determined to be the pulse waveform of the signal of the optimized quantum signal link.

[0040] In the above method, preferably, the number of first pulse waveforms corresponding to the target time constant is at least two; determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized comprises:

[0041] determining at least two second pulse waveforms corresponding to the target time constant;

[0042] splicing the second pulse waveform and the first pulse waveform into a target pulse waveform according to the pulse time;

[0043] A plurality of target pulse waveforms are spliced ​​according to pulse time to obtain a pulse waveform of a signal of an optimized quantum signal link.

[0044] On the other hand, the present application provides a device for optimizing a signal of a quantum signal link, comprising:

[0045] A first determination module is used to determine a target time constant that characterizes the signal transmission characteristics of a quantum signal link according to the response of the frequency of the quantum bit to the pulse signal; wherein the quantum signal link includes a signal source, a high-pass filter, and a quantum bit on a quantum processing unit that are electrically connected in sequence through a signal transmission line; and the signal source is used to output a pulse signal that regulates the frequency of the quantum bit;

[0046] A second determination module is used to determine a first pulse waveform according to the target time constant; wherein the first pulse waveform is used to compensate for the distortion of the pulse signal after the pulse ends;

[0047] The third determination module is used to determine the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized.

[0048] In another aspect, the present application provides a quantum signal link, comprising a signal source, a high-pass filter, and a quantum bit on a quantum processing unit, which are electrically connected in sequence through a signal transmission line; the signal source is used to output a pulse signal for regulating the frequency of the quantum bit;

[0049] The pulse signal is optimized and determined by any one of the above methods.

[0050] On the other hand, the present application provides a quantum computer, which uses any of the above methods to optimize the waveform of a pulse signal and outputs an optimized pulse signal, or includes the above device or includes the above quantum signal link.

[0051] Compared with the prior art, the present application filters out the low-frequency noise of the flux modulation circuit by setting a high-pass filter in the quantum signal link; and determines the target time constant that characterizes the signal transmission characteristics of the quantum signal link by testing the frequency response of the quantum bit to the pulse signal, and determines the first pulse waveform for compensating the residual distortion according to the target time constant, thereby obtaining the optimized pulse signal waveform that compensates for the distortion caused by the high-pass filter, so that when the signal source outputs the signal of the optimized quantum signal link to the quantum bit according to the optimized pulse signal waveform, the working frequency of the quantum bit is accurately regulated to the target value, thereby improving the decoherence performance of the quantum bit.

[0052] The signal optimization device, quantum signal link, and quantum computer of the quantum signal link proposed in this application belong to the same application concept and therefore have the same beneficial effects, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic diagram of pulse waveform distortion caused by a high-pass filter in the prior art;

[0054] Figure 2 A schematic diagram of a flow chart of a signal optimization method for a quantum signal link provided in an embodiment of the present application;

[0055] Figure 3 A schematic diagram of a process for determining a target time constant provided in an embodiment of the present application;

[0056] Figure 4 A schematic diagram of the composition of a first pulse waveform provided in an embodiment of the present application;

[0057] Figure 5 A schematic diagram of a measurement result of measuring the frequency of a quantum bit by a Ramsey experiment provided in an embodiment of the present application;

[0058] Figure 6 A schematic diagram of a process for determining an initial time constant provided in an embodiment of the present application;

[0059] Figure 7 A schematic diagram of the corresponding relationship between the quantum state of a quantum bit and the initial time constant provided in an embodiment of the present application;

[0060] Figure 8 A schematic diagram of a process for determining a first pulse waveform provided in an embodiment of the present application;

[0061] Fig. 9 A waveform diagram of a first pulse waveform provided in an embodiment of the present application;

[0062] Fig.10 A schematic diagram of a first pulse waveform and its response waveform provided in an embodiment of the present application;

[0063] Fig.11 A schematic diagram of a flow chart of a signal for determining an optimized quantum signal link provided in an embodiment of the present application;

[0064] Fig.12 A waveform diagram of a pulse waveform of a signal of an optimized quantum signal link provided in an embodiment of the present application;

[0065] Fig.13 A schematic diagram of another process for determining a signal of an optimized quantum signal link provided in an embodiment of the present application;

[0066] Fig.14 A waveform diagram of a pulse waveform of a signal of another optimized quantum signal link provided in an embodiment of the present application;

[0067] Fig.15 A schematic diagram of a process for determining an optimized pulse signal waveform including a first pulse waveform provided in an embodiment of the present application;

[0068] Fig.16 A waveform diagram of a pulse waveform of a signal of a quantum signal link including a first pulse waveform after determining optimization provided in an embodiment of the present application;

[0069] Fig.17 A schematic diagram of a process for determining an optimized pulse signal waveform including a plurality of first pulse waveforms provided in an embodiment of the present application;

[0070] Fig.18 A waveform diagram of a pulse waveform of a signal of a quantum signal link including a plurality of first pulse waveforms after determining optimization provided in an embodiment of the present application;

[0071] Fig.19 A schematic diagram of the composition of a signal optimization device for a quantum signal link provided in an embodiment of the present application.

[0072] In the reference numerals:

[0073] 10 - a first determination module, 20 - a second determination module, 30 - a third determination module. DETAILED DESCRIPTION

[0074] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limitations on the present application.

[0075] In the description of the present application, it should be understood that the terms "center", "up", "down", "left", "right", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0076] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0077] For quantum processing units, in order to ensure the accuracy of quantum computing, all computing operations need to be completed within the decoherence time. Therefore, the decoherence performance of the quantum processing unit needs to be improved as much as possible. The decoherence performance of the quantum processing unit is closely related to the operating frequency of the quantum bit. When the operating frequency of the quantum bit deviates from the natural frequency, the decoherence performance will drop significantly. Among them, the natural frequency of the quantum bit is the operating frequency when only a DC voltage signal is applied to the flux modulation circuit of the quantum bit. At this time, no pulse signal is applied to the flux modulation circuit of the quantum bit or the amplitude of the applied pulse signal is zero, that is, the filter will not affect the natural frequency of the quantum bit.

[0078] Flux modulation is usually used to control the operating frequency of quantum bits. A pulse signal is applied to the flux modulation circuit of the quantum bit through a quantum signal link, and multiple filters are set on the signal transmission link between the quantum signal link and the quantum processing unit to filter out low-frequency noise signals.

[0079] In the field of quantum measurement and control, the quantum computing measurement and control system is a system for controlling and measuring quantum processing units, which integrates a number of signal sources, signal acquisition equipment, signal processing equipment, etc. Among them, the signal source generally includes various instruments such as DC signal source, pulse signal source, microwave signal source, etc. The signal source is connected to the magnetic flux modulation circuit of the quantum processing unit through a signal transmission line, and a filter is set on the signal transmission line. A quantum signal link for transmitting signals is formed between the signal output channel of the signal source and the quantum bit of the quantum processing unit.

[0080] As attached Figure 1 As shown, the applicant sets a high-pass filter at the signal output port of the signal source in the quantum signal link to filter the low-frequency noise signal in the signal transmission line connected to the signal output port; and sets the pulse waveform of the pulse signal to be output, such as the pulse waveform indicated by the black solid line, with an amplitude of a s , time is t s ; The signal is transmitted to the flux modulation circuit of the quantum bit on the quantum processing unit through the signal transmission line; at the same time, an oscilloscope or other measuring equipment is used to measure the pulse waveform of the received pulse signal on the flux modulation circuit. As shown in the dotted line, the pulse signal output by the signal is distorted after being filtered by the high-pass filter. Not only the pulse time t s The internal voltage amplitude is distorted and cannot maintain a fixed value. s , which is called waveform distortion; s After the end, an amplitude of a will be generated t The residual voltage is called residual distortion. Both waveform distortion and residual distortion will directly affect the regulation of the pulse signal on the working frequency of the quantum bit, thereby reducing the decoherence performance of the quantum bit.

[0081] In this embodiment, the pulse waveform represented by the black solid line is defined as the pulse signal waveform to be optimized, and the waveform distortion and residual distortion caused by the high-pass filter need to be compensated to ensure that the waveform of the pulse signal transmitted to the quantum bit is the same as the pulse signal waveform to be optimized. The shape of the pulse waveform after compensating for the waveform distortion and residual distortion is related to the waveform parameters of the pulse signal waveform to be optimized.

[0082] As attached Figure 2 As shown, in this embodiment, the applicant proposes a method for optimizing the signal of a quantum signal link, comprising:

[0083] Step S10: determining a target time constant characterizing the signal transmission characteristics of a quantum signal link according to the response of the frequency of the quantum bit to the pulse signal.

[0084] In this embodiment, the quantum signal link defined in this application includes a signal source, a high-pass filter, and a quantum bit on a quantum processing unit that are electrically connected in sequence through a signal transmission line, wherein the high-pass filter is provided at a signal output port of the signal source. The time constant of the quantum signal link in this application is the time required for the output signal energy of the system to decay from a steady-state value to about 63.2% of the steady-state value. The shorter the time, the faster the response of the characterization system to signal changes.

[0085] The time constant of the quantum signal link is related to the performance parameters of the signal source, the high-pass filter, and the signal transmission line. For the quantum signal link defined in this application, an appropriate time constant of the quantum signal link can be determined to compensate for the distortion caused by the high-pass filter.

[0086] As described above, the distortion caused by the high-pass filter will directly affect the frequency regulation effect of the pulse signal output by the signal source on the quantum bit. Therefore, in this embodiment, the appropriate time constant of the quantum signal link can be selected by testing, and the regulation result of the pulse signal output by the quantum signal link on the quantum bit frequency can be measured. The time constant that meets the expected regulation result is selected as the target time constant to compensate for the distortion caused by the high-pass filter.

[0087] Using quantum bits as measurement media, the target time constant of the quantum signal link is determined by measuring the frequency of the quantum bits. The effects of the high-pass filter and other influencing factors on the distortion in the entire measurement and control link and measurement and control system are included to ensure the compensation effect of the first pulse waveform determined based on the target time constant on the residual distortion, and ensure that the optimized pulse signal waveform achieves the expected effect on the adjustment of the quantum bit frequency.

[0088] Step S20: determining a first pulse waveform according to the target time constant; wherein the first pulse waveform is used to compensate for the distortion of the pulse signal after the pulse ends.

[0089] The waveform distortion of the pulse signal caused by the high-pass filter can be determined based on the parameters of the pulse signal waveform to be optimized, including the residual distortion affected by it. After the target time constant of the quantum signal link is determined in step S10, the first pulse waveform can be determined. Specifically, the first pulse waveform is used to compensate for the distortion of the pulse signal waveform after the pulse ends, corresponding to the attached Figure 1 The median amplitude is a s The residual distortion of the pulse signal waveform can quickly return to zero after the pulse time ends, avoiding affecting the control effect of the operating frequency of the quantum bit.

[0090] Combined with the above description, the distortion caused by the high-pass filter to the pulse signal waveform to be optimized with different parameters is also different, and correspondingly, the target time constant of the quantum signal link determined by measurement is also different, and then the first pulse waveform is also different. In specific applications, the corresponding target time constant can be obtained by testing in step S10.

[0091] During the specific test, time constants of different values ​​are determined, and then the corresponding first pulse waveform is determined. Then, the signal source in the quantum signal link outputs the corresponding pulse signal to the quantum bit according to the first pulse waveform, and then the operating frequency of the quantum bit is measured by the measuring equipment.

[0092] Step S30: determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized.

[0093] The first pulse waveform determined in step S20 is used to compensate for the distortion of the pulse waveform after the pulse ends caused by the high-pass filter. Figure 1 The median amplitude is a s residual distortion; Figure 1 In t s The distortion of the waveform amplitude within time can also determine the corresponding compensation waveform through the target time constant. Among them, the pulse signal waveform to be optimized is connected with the first pulse waveform in pulse time, so that the pulse waveform composed of the pulse signal waveform to be optimized and the first pulse waveform is the pulse waveform of the signal of the optimized quantum signal link, and the residual distortion is compensated, so that the pulse signal output according to the pulse waveform of the signal of the optimized quantum signal link improves the accuracy of the control of the working frequency of the quantum bit.

[0094] In summary, this embodiment filters out the low-frequency noise of the flux modulation circuit by setting a high-pass filter in the quantum signal link; and determines the target time constant of the quantum signal link by testing the frequency of the quantum bit, and determines the first pulse waveform for compensating for the residual distortion according to the target time constant, thereby obtaining an optimized pulse signal waveform for compensating for the distortion caused by the high-pass filter, so that when the signal of the optimized quantum signal link output by the signal source according to the optimized pulse signal waveform reaches the quantum bit, the operating frequency is accurately adjusted to the target value, thereby improving the decoherence performance of the quantum bit.

[0095] As attached Figure 3 As shown, in this embodiment, the applicant proposes a method for determining a target time constant of a quantum signal link, comprising:

[0096] Step S101: determining a plurality of corresponding second pulse waveforms according to the pulse signal waveform to be optimized and a plurality of preset time constants within a first preset range; wherein the second pulse waveform is formed by splicing the first waveform and the second waveform according to the pulse time.

[0097] Combined with Figure 1 And attached Figure 4 As shown, attached Figure 4 The first waveform and the second waveform with different preset time constants are illustrated, which are spliced ​​into a second pulse waveform according to the pulse time, wherein the second pulse waveform with a black solid line is a waveform with one of the preset time constants, and the second pulse waveform with a black dotted line is a waveform with another preset time constant; both are used to compensate for the amplitude distortion of the pulse waveform within the pulse time caused by the high-pass filter. Specifically, the waveform amplitude of the first waveform can be described as:

[0098] Y c =a s (1+t s / τ)(1)

[0099] Among them, Y in formula 1 c is the amplitude of the first waveform, a s is the amplitude of the pulse signal waveform to be optimized, t s For the pulse time of the pulse signal waveform to be optimized, please refer to the attached Figure 1 , τ is a preset time constant; it can be found that the amplitude of the first waveform changes with the preset time constant t.

[0100] The second waveform has a fixed amplitude, and its amplitude can be described as:

[0101] Y b =a s (t s / τ)(2)

[0102] Among them, Y in formula 2 b is the amplitude of the second waveform, a s is the amplitude of the pulse signal waveform to be optimized, t s is the pulse time of the pulse signal waveform to be optimized, and τ is the preset time constant; it can be found that the amplitude of the second waveform is fixed within the pulse time, and its specific amplitude also changes with the preset time constant t, as shown in the attached figure. Figure 4 The second waveform is the solid black line and the second waveform is the dashed black line.

[0103] Combining the description formulas of the first waveform and the second waveform, it can be found that each preset time constant corresponds to a first waveform and a second waveform, that is, each preset time constant corresponds to a second pulse waveform. Figure 4As shown in the figure, a second pulse waveform is formed by splicing the first waveform and the second waveform with different preset time constants, wherein the second pulse waveform of the black solid line is a waveform of one of the preset time constants, and the amplitude of the first waveform is Y c1 , the amplitude of the second waveform is Y b1 The second pulse waveform of the black dashed line is another waveform with a preset time constant, and the amplitude of the first waveform is Y c2 , the amplitude of the second waveform is Y b2 .

[0104] By using a plurality of preset time constants within the first preset range, a plurality of second pulse waveforms can be determined, and the first waveform and the second waveform corresponding to each second pulse waveform are different. For example, the first preset range can be set to {0, 1500} nanoseconds, and then the step value is set to obtain a plurality of preset time constants.

[0105] In addition, continue to attach Figure 4 As shown, combining the amplitude description formula of the first waveform and the second waveform, it can be found that when t s The larger the Y c The larger the value of b The larger the value of , that is, the longer the pulse time of the pulse signal waveform to be optimized, the larger the amplitude of the second pulse signal used for compensation.

[0106] Step S102: Outputting corresponding pulse signals to the qubit according to the plurality of second pulse waveforms. Specifically, for each second pulse waveform, a corresponding pulse signal is output to the qubit through a signal source to adjust the frequency of the qubit.

[0107] Step S103: performing a Ramsey experiment on the quantum bit during the duration of the second waveform to obtain a measurement frequency of the quantum bit.

[0108] In the quantum field, the frequency measurement of quantum bits usually adopts the Ramsey experiment. In this embodiment, the frequency of quantum bits is measured by the Ramsey experiment. Specifically, the Ramsey experiment refers to a process of applying two π / 2 quantum logic gate operations to a quantum bit, with the time interval between the two operations being t, applying a read pulse to the quantum bit after the second π / 2 quantum logic gate operation to obtain the excited state distribution P1(t) of the quantum bit, and changing the time interval t to obtain P1(t). Among them, the π / 2 quantum logic gate operation is used to manipulate the quantum state of the quantum bit to evolve 90 degrees along the Z axis in the Bloch sphere.

[0109] The result of a typical Ramsey experiment is that P1(t) satisfies the exponential oscillation decay mathematical model with time interval t as follows:

[0110]

[0111] In the above formula 3, A and B are fitting coefficients, T0 is the decoherence time of the quantum bit, and f d is the carrier frequency of the microwave pulse signal corresponding to the π / 2 quantum logic gate operation, f0 is the oscillation frequency of the quantum bit, and f0 is related to the real frequency f of the quantum bit. q , the carrier frequency of the π / 2 quantum logic gate operation satisfies:

[0112] f0(f d )=|f q -f d |(4)

[0113] Based on Formula 3 and Formula 4, we can obtain the result of the Ramsey experiment, that is, the oscillation frequency of the curve is equal to the difference between the carrier frequency of the quantum logic gate operation and the real frequency of the quantum bit. Therefore, in addition to being able to be used to obtain the decoherence time of the quantum bit, the Ramsey experiment can also accurately obtain the frequency of the quantum bit at the same time.

[0114] In addition, in this embodiment, a Ramsey experiment is performed on the quantum bit during the duration of the second waveform, and the first waveform is used to compensate for the waveform distortion caused by the high-pass filter to the pulse signal waveform to be optimized during the pulse time. After the waveform distortion compensation, the amplitude of the pulse waveform is stabilized at a fixed amplitude, that is, the amplitude of the second waveform, thereby ensuring the stability of the frequency control of the quantum bit. The relatively stable frequency of the quantum bit can be obtained by measuring the pulse duration of the second waveform through the Ramsey experiment, thereby ensuring the accuracy of the measurement.

[0115] It should be added that the frequency of the quantum bit can also be measured by the energy spectrum experiment. Relatively speaking, the energy spectrum experiment is simpler to measure, and the accuracy of the measurement result is lower than that of the Ramsey experiment. In this embodiment, in order to ensure the accuracy of the compensation of the distortion, the Ramsey experiment is used to measure the frequency of the quantum bit.

[0116] Step S104: determining a preset time constant when the measurement frequency is the same as the natural frequency of the quantum bit as the target time constant.

[0117] The high-pass filter causes residual distortion in the pulse signal after the pulse time ends, and the pulse voltage is not zero. The voltage caused by the residual distortion needs to be compensated to zero through the first pulse waveform. Therefore, a pulse signal with zero amplitude is applied to the flux modulation circuit of the quantum bit, and the frequency of the quantum bit is measured as the natural frequency, which is used to measure the compensation effect of the first pulse waveform on the residual distortion.

[0118] In the above steps S101 to S103, a Ramsey experiment is performed every time a preset time constant is traversed within the first preset range to obtain a measurement frequency of the quantum bit; when all the preset time constants within the first preset range are traversed, the corresponding relationship between the measurement frequency of several groups of quantum bits and the preset time constants can be obtained, and the corresponding relationship is curve fitted to obtain a fitting curve, as shown in the attached figure. Figure 5 The oblique line in FIG.

[0119] Continue as attached Figure 5 As shown, attached Figure 5 The horizontal axis represents the preset time constant, which is in nanoseconds, and the horizontal axis is the measurement frequency of the quantum bit. The horizontal line in the figure is the natural frequency of the quantum bit, which corresponds to the frequency measured when a DC voltage signal and a pulse signal with zero amplitude are applied to the magnetic flux modulation circuit of the quantum bit. At this time, there is no high-pass filter on the magnetic flux modulation circuit, and the frequency of the measured quantum bit is the natural frequency. The intersection of the horizontal line and the oblique line in the figure is the same as the measurement frequency of the quantum bit. The preset time constant value corresponding to the horizontal axis of the coordinate at this time is determined to be the target time constant. For example, attached Figure 5 The target time constant in is 1060 nanoseconds.

[0120] By adopting the above steps S101 to S104, the relationship between the second pulse waveform and the time constant for compensating for the distortion is determined according to the distortion effect of the high-pass filter on the pulse signal waveform to be optimized, and the frequency of the quantum bit is measured by the Ramsey experiment to determine the target time constant that can compensate for the distortion and the corresponding second pulse waveform.

[0121] It is conceivable that whether the first preset range of the preset time constant in step S101 is appropriate will directly affect the efficiency of the Ramsey experiment in determining the target time parameter. In this embodiment, the applicant proposes a method for quickly determining the first preset range of the preset time constant.

[0122] Specifically, as attached Figure 6 As shown, before determining the corresponding plurality of second pulse waveforms according to the pulse signal waveform to be optimized and a plurality of preset time constants within the first preset range, the method further includes:

[0123] Step S111: determining an initial compensation waveform according to the pulse signal waveform to be optimized and a plurality of preset time constants within a second preset range; wherein the initial compensation waveform is formed by splicing the first compensation waveform and the second compensation waveform according to the pulse time.

[0124] This step S111 is the same as step S101, and the initial compensation waveform is determined by the same method as step S101. That is, the initial compensation waveform is the same as the second pulse waveform, the amplitude description of the first compensation waveform is the same as the amplitude description of the first waveform, and the amplitude description of the second compensation waveform is the same as the amplitude description of the second waveform. In addition, the second preset range is a relatively large range, such as {0, 2000} nanoseconds, and its step value can be set to be relatively large, such as 50 nanoseconds.

[0125] Step S112: Outputting corresponding pulse signals to the qubit according to the plurality of initial compensation waveforms. Specifically, for each initial compensation waveform, a corresponding pulse signal is output to the qubit through a signal source to adjust the operating frequency of the qubit.

[0126] Step S113: During the duration of the second compensation waveform, the quantum state of the qubit is regulated to an excited state. Specifically, during the duration of the second compensation waveform, a π quantum logic gate operation is applied to the quantum state control circuit of the qubit to regulate the quantum state of the qubit to an excited state. The π quantum logic gate operation is used to manipulate the quantum state of the qubit to evolve 180 degrees along the Z axis in the Bloch sphere. In this embodiment, the π quantum logic gate operation is used to regulate the quantum state of the qubit from the ground state to the excited state.

[0127] Step S114: measuring the probability that the quantum state of the quantum bit is an excited state after the pulse time of the pulse signal corresponding to the initial compensation waveform.

[0128] In the above steps S111-S112, each preset time constant is traversed within the second preset range to obtain the corresponding initial compensation waveform, and the corresponding pulse signal is applied to the quantum bit to adjust the frequency of the quantum bit to the corresponding frequency. After the pulse signal is applied, since the frequency of the quantum bit directly affects the control effect of the π quantum logic gate operation on the quantum state of the quantum bit, each time the preset time constant is traversed, the control effect of the quantum state of the quantum bit through step S113 is different, and the probability of controlling the quantum state of the quantum bit to the excited state is different.

[0129] Step S115: determining a preset time constant when the probability that the quantum state of the quantum bit is an excited state is the maximum as the initial time constant.

[0130] As described above, when the preset time constant is determined to be appropriate, the second compensation waveform can compensate for the distortion effect of the high-pass filter on the pulse signal waveform to be optimized, so that the second compensation waveform can more accurately control the frequency of the corresponding pulse signal on the quantum bit. At this time, the π quantum logic gate operation applied in step S113 can maximize the probability that the quantum state of the quantum bit is an excited state. Therefore, by measuring in step S114, the corresponding relationship between the probability that the quantum state of the quantum bit is an excited state and the preset time constant can be obtained, and the preset time constant when the probability that the quantum state of the quantum bit is an excited state is the maximum is determined as the initial time constant.

[0131] As attached Figure 7 The corresponding relationship between the probability of the quantum state of the quantum bit of the example being the excited state and the preset time constant, the horizontal axis in the figure represents the preset time constant in microseconds, and the vertical axis represents the probability of the excited state, which can be calculated based on the attached Figure 7 The curve in determines the initial time constant to be 0.85 microseconds, or 850 nanoseconds.

[0132] Step S116: determining the first preset range according to the initial time constant.

[0133] Combined with the above description, when the preset time constant is determined to be appropriate, the second compensation waveform can compensate for the distortion effect of the high-pass filter on the pulse signal waveform to be optimized, so that the pulse signal corresponding to the second compensation waveform can more accurately control the frequency of the quantum bit. Therefore, the initial time constant determined at this time is closer to the target time constant. The first time range is determined based on the initial time constant, and the first preset range can be determined as a suitable range interval, ensuring that the corresponding target time constant can be quickly determined by traversing the time constant within the first preset range and performing the Ramsey experiment by adopting steps S101-S104.

[0134] As attached Figure 7 The initial time constant determined in is 850 nanoseconds, and the first time range is determined to be {700, 1150} nanoseconds, which is much smaller than the {0, 1500} nanosecond range in the previous example. The corresponding target time constant can be quickly determined, the measurement time is shortened, and the measurement efficiency is improved.

[0135] As attached Figure 8 As shown, the first pulse waveform is determined according to the target time constant and the pulse signal waveform to be optimized, including:

[0136] Step S201: Determine that the correspondence between the time constant, the distortion amplitude, the pulse amplitude and the pulse time is a first preset relationship; wherein the distortion amplitude is the amplitude of the distortion of the pulse signal waveform to be optimized after the pulse time ends due to the influence of the high-pass filter, and the pulse amplitude and the pulse time are waveform parameters of the first pulse waveform.

[0137] The distortion effect of the high-pass filter on the pulse signal waveform to be optimized includes the residual distortion after the pulse time ends. Figure 1 As shown, the distortion amplitude of the residual distortion is a t , and the first pulse waveform is used to compensate for the residual distortion of the pulse signal waveform after the pulse ends.

[0138] Combined with Figure 1 , Attachment Fig. 9 And attached Fig.10 As shown, attached Fig. 9 The waveform of the pulse signal to be optimized that reaches the quantum bit after residual distortion occurs through the high-pass filter, the first pulse waveform, and the waveform of the first pulse waveform response are exemplified. It can be found that the first pulse waveform response has a waveform amplitude in the opposite direction of the residual distortion after the pulse time ends. When the distortion amplitude of the residual distortion is superimposed with the amplitude of the first pulse waveform response, the amplitude of the pulse signal can quickly return to zero after the pulse time ends, which is used to compensate for the residual distortion and avoid affecting the frequency adjustment of the quantum bit.

[0139] The residual distortion caused by the high-pass filter is compensated by the first pulse waveform response. The pulse amplitude and pulse time of the first pulse waveform have a relative relationship with the distortion amplitude. The relative relationship is determined as a first preset relationship, specifically:

[0140]

[0141] Among them, t in formula 5 r represents the pulse time of the first pulse waveform, ln is a logarithmic expression, a r represents the pulse amplitude of the first pulse waveform, a t Represents the distortion amplitude, and τ represents the time constant. The distortion amplitude and the time constant can be determined as specific values. The pulse time and the pulse amplitude of the first pulse waveform have a logarithmic relationship. The pulse amplitude can be set and the appropriate pulse time can be matched according to the above formula; the pulse time can also be set, and the appropriate pulse amplitude can be matched, which is convenient for flexibly setting the pulse time of the first pulse waveform in specific applications, and improving the application flexibility of the distortion compensation caused by the high-pass filter.

[0142] Step S202: determining a target distortion amplitude according to the target time constant.

[0143] In combination with the above description, the second pulse waveform is used to compensate for the waveform distortion of the pulse signal waveform to be optimized within the pulse time, and the first pulse waveform is used to compensate for the residual distortion caused by the high-pass filter after the pulse of the pulse signal waveform to be optimized ends, that is, the pulse end time of the second pulse waveform is consistent with the pulse start time of the first pulse waveform. The amplitude of the second pulse waveform at the pulse end time is positive Y b , the influence of residual distortion is negative amplitude. According to electromagnetic balance theory, the distortion amplitude of residual distortion is a t With Y b The absolute values ​​of the amplitudes are equal, and the amplitude directions are opposite. Therefore, after the amplitude of the second waveform is determined according to the target time constant, the target distortion amplitude can be determined.

[0144] Step S203: Determine the target pulse amplitude and target pulse time of the first pulse waveform according to the target distortion amplitude, the target time constant and the first preset relationship. Combined with Formula 5, when the target distortion amplitude a is determined, t and the target time constant τ, the target pulse amplitude and target pulse time with a corresponding relationship can be determined.

[0145] The target pulse time and the target pulse amplitude have a logarithmic relationship, and the target pulse amplitude can be set and the appropriate target pulse time can be matched according to the above formula. In addition, the target pulse time can also be set, and the appropriate target pulse amplitude can be matched, which is convenient for flexibly setting the pulse time of the first pulse waveform in specific applications, and improving the application flexibility of the distortion compensation caused by the high-pass filter.

[0146] Step S204: Determine the first pulse waveform according to the target pulse amplitude and the target pulse time. After the target pulse time and the target pulse amplitude are determined, the specific shape of the first pulse waveform is correspondingly determined.

[0147] As attached Fig.11 As shown, after the first pulse waveform is determined, the signal of the optimized quantum signal link is determined according to the first pulse waveform and the pulse signal waveform to be optimized, including:

[0148] Step S301: splicing the pulse signal waveform to be optimized and the first pulse waveform according to the pulse time.

[0149] Step S302: Determine that the spliced ​​pulse waveform is the pulse waveform of the signal of the optimized quantum signal link.

[0150] Combine steps S101 to S104 to determine the target time constant, then combine steps S201 to S203 to determine the first pulse waveform according to the target time constant, and splice the first pulse waveform and the pulse signal waveform to be optimized according to the pulse time. The spliced ​​pulse waveform is as shown in the attached figure. Fig.12 The pulse waveform of the signal of the optimized quantum signal link in the example; the signal source outputs the signal of the optimized quantum signal link according to the optimized pulse waveform.

[0151] The first pulse waveform is used to compensate for the residual distortion of the pulse signal caused by the high-pass filter after the pulse time ends. The pulse waveform of the signal of the optimized quantum signal link obtained by splicing can compensate for the residual distortion caused by the high-pass filter, ensuring that when the pulse signal output according to the pulse waveform of the signal of the optimized quantum signal link is transmitted to the quantum bit, the frequency regulation effect of the quantum bit reaches the expected effect.

[0152] As attached Fig.13 As shown, the present application also provides another method for determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized, comprising:

[0153] Step S311: Determine a second pulse waveform corresponding to the target time constant.

[0154] Step S312: splicing the second pulse waveform and the first pulse waveform according to the pulse time.

[0155] Step S313: Determine that the spliced ​​pulse waveform is the pulse waveform of the signal of the optimized quantum signal link.

[0156] In combination with the above description, the amplitudes of the first waveform and the second waveform corresponding to the target time constant are determined according to the method for determining the second pulse waveform in step S101, and the first waveform and the second waveform are spliced ​​according to the pulse time to obtain the second pulse waveform; then the second pulse waveform and the first pulse waveform are spliced ​​according to the pulse time, and the spliced ​​pulse waveform is determined as the pulse waveform of the signal of the optimized quantum signal link. The spliced ​​pulse waveform is as shown in the attached figure. Fig.14 Optimized pulse shape for example.

[0157] The first pulse waveform is used to compensate for the residual distortion after the pulse time is ended caused by the high-pass filter, and the second pulse waveform is used to compensate for the waveform distortion within the pulse time caused by the high-pass filter. The pulse waveform obtained by splicing the first pulse waveform and the second pulse waveform according to the pulse time can compensate for the residual distortion and the waveform distortion at the same time, ensuring that when the corresponding pulse signal output according to the pulse waveform of the signal of the optimized quantum signal link is transmitted to the quantum bit, the frequency regulation effect of the quantum bit reaches the expected effect.

[0158] Combined with Figure 1 , Attachment Fig.12 and attached Fig.14 As shown, in the above embodiment, the effect of compensating for a pulse signal waveform to be optimized is described. In some quantum computing processes, multiple continuous pulse signals need to be applied to the quantum bit, that is, multiple continuous pulse signal waveforms to be optimized will be affected by the high-pass filter and distorted.

[0159] As attached Fig.15 As shown, in this embodiment, for the above-mentioned situation of applying multiple continuous pulse signals to quantum bits, the applicant provides a method for determining the signal of the optimized quantum signal link. Specifically, a plurality of first pulse waveforms can be determined according to a target time constant and a pulse signal waveform to be optimized, and the signal of the optimized quantum signal link is determined according to the first pulse waveform and the pulse signal waveform to be optimized, including:

[0160] Step S321: Determine at least two second pulse waveforms corresponding to the target time constant.

[0161] Repeat steps S101 to S105 to determine the corresponding second pulse waveform for each pulse signal waveform to be optimized. When several pulse signal waveforms to be optimized are the same, their corresponding second pulse waveforms are also the same, except that the start time and end time of their pulse waveforms are different.

[0162] Step S322: splicing at least two of the second pulse waveforms and the first pulse waveform according to pulse time.

[0163] Step S323: Determine that the spliced ​​pulse waveform is the pulse waveform of the signal of the optimized quantum signal link.

[0164] It should be added that the first pulse waveform is used to compensate for the residual distortion after the pulse time of the second pulse waveform ends, and the pulse amplitude is compensated to zero. In this embodiment, a plurality of continuous second pulse waveforms are first used to compensate for the waveform distortion within the pulse time, and then a first pulse waveform is used to compensate for the residual distortion of a plurality of continuous second pulse waveforms. That is, the residual distortion of a plurality of continuous second pulse waveforms between the first pulse waveforms is superimposed, so the waveform amplitude of each second pulse waveform also needs to be superimposed.

[0165] Specifically, when the amplitude of each second pulse waveform is determined by using the above formula 1 and formula 2, t in formula 1 and formula 2 is s For example, in the formula for determining the amplitude of the first and second pulse waveforms, the pulse time is t s In the second pulse waveform amplitude determination formula, the pulse time is 2*ts In the third formula for determining the amplitude of the second pulse waveform, the pulse time is 3*t s , and so on. The pulse waveform of the signal of the optimized quantum signal link is shown in the attached figure. Fig.16 shown.

[0166] As attached Fig.17 As shown, in this embodiment, for the above-mentioned situation of applying multiple continuous pulse signals to quantum bits, the applicant provides another method for determining the signal of the optimized quantum signal link. Specifically, the number of first pulse waveforms corresponding to the target time constant is at least two; the signal of the optimized quantum signal link is determined based on the first pulse waveform and the pulse signal waveform to be optimized, including:

[0167] Step S331: Determine at least two second pulse waveforms corresponding to the target time constant.

[0168] Step S332: splicing the second pulse waveform and the first pulse waveform into a target pulse waveform according to the pulse time.

[0169] A number of first pulse waveforms and second pulse waveforms with continuous pulse times are determined based on the target time constant. At this time, the residual distortion of each second pulse waveform at the end of the pulse is compensated by the corresponding first pulse waveform, and the amplitude of the pulse waveform after compensation tends to zero, that is, each target pulse waveform is compensated for waveform distortion and residual distortion, and its waveform amplitude tends to zero after the pulse time of each target pulse waveform ends.

[0170] Step S333: splicing a plurality of said target pulse waveforms according to the pulse time to obtain the pulse waveform of the signal of the optimized quantum signal link. A plurality of target pulse waveforms are spliced ​​according to the pulse time, and the spliced ​​pulse waveform is as shown in the attached figure. Fig.18 shown.

[0171] Attached Fig.16 and attached Fig.18 In the figure, the pulse waveforms at the top are several continuous pulse signal waveforms to be optimized, and the pulse waveforms at the bottom are the optimized pulse signal waveforms.

[0172] Whether using steps S321-S323 to determine the signal of the optimized quantum signal link, or using steps S331-S333 to determine the pulse waveform of the signal of the optimized quantum signal link, the residual distortion and the waveform distortion can be compensated at the same time to ensure that when the pulse signal output according to the pulse waveform of the signal of the optimized quantum signal link is transmitted to the quantum bit, the frequency regulation effect of the quantum bit reaches the expected effect.

[0173] When the signal of the optimized quantum signal link is determined by using steps S321 to S323, the amplitudes of several second pulse waveforms will gradually increase, so the number of second pulse waveforms to be spliced ​​needs to be within a preset range to avoid the amplitude of the second pulse waveform exceeding the output range of the signal source after increasing.

[0174] Based on the same application concept, the embodiment of the present application also provides a signal optimization device for a quantum signal link, including: a first determination module 10, the first determination module is used to determine the target time constant that characterizes the signal transmission characteristics of the quantum signal link according to the response of the frequency of the quantum bit to the pulse signal; wherein the quantum signal link includes a signal source, a high-pass filter, and a quantum bit on a quantum processing unit that are electrically connected in sequence through a signal transmission line; the signal source is used to output a pulse signal that regulates the frequency of the quantum bit; a second determination module 20 is used to determine a first pulse waveform according to the target time constant; wherein the first pulse waveform is used to compensate for the distortion of the pulse signal after the pulse ends; a third determination module 30 is used to determine the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized.

[0175] Among them, the first determination module 10, the second determination module 20, and the third determination module 30 are generally data processing software in the host computer, which are communicatively connected to the quantum signal link, and perform tests on the quantum processing unit through the quantum signal link to determine the target time constant, and determine the corresponding optimized pulse signal waveform based on the target time constant.

[0176] Based on the same application concept, an embodiment of the present application also provides a quantum signal link, including a signal source, a high-pass filter, and a quantum bit on a quantum processing unit, which are electrically connected in sequence through a signal transmission line; the signal source is used to output a pulse signal for regulating the frequency of the quantum bit; the pulse signal is optimized and determined using any one of the above methods.

[0177] Based on the same application concept, an embodiment of the present application also provides a quantum computer, which uses any of the above methods to optimize the waveform of a pulse signal and outputs an optimized pulse signal, or includes the above device or includes a quantum signal link as described above.

[0178] In the description of this specification, the description with reference to the terms "some embodiments" or "examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0179] The above are only preferred embodiments of the present application and do not have any limiting effect on the present application. Any technical personnel in the relevant technical field, without departing from the scope of the technical solution of the present application, may make any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present application, which shall be deemed as the content of the technical solution of the present application and still fall within the protection scope of the present application.

Claims

1. A method for optimizing a signal of a quantum signal link, characterized in that: The quantum signal link includes a signal source, a high-pass filter, and a quantum bit on a quantum processing unit that are electrically connected in sequence through a signal transmission line; The signal source is used to output a pulse signal for regulating the frequency of the quantum bit; The method comprises: Determining a target time constant characterizing a signal transmission characteristic of a quantum signal link according to a response of the frequency of the quantum bit to the pulse signal; Determining a first pulse waveform according to the target time constant; wherein the first pulse waveform is used to compensate for the distortion of the pulse signal after the pulse ends; The signal of the optimized quantum signal link is determined according to the first pulse waveform and the pulse signal waveform to be optimized.

2. The method according to claim 1, characterized in that The step of determining a target time constant characterizing a signal transmission characteristic of a quantum signal link according to a response of the frequency of the quantum bit to the pulse signal comprises: Determine a plurality of corresponding second pulse waveforms according to the pulse signal waveform to be optimized and a plurality of preset time constants within a first preset range; wherein the second pulse waveform is formed by splicing the first waveform and the second waveform according to the pulse time; Outputting corresponding pulse signals to the quantum bits respectively according to a plurality of the second pulse waveforms; performing a Ramsey experiment on the qubit during the duration of the second waveform to obtain a measurement frequency of the qubit; The preset time constant when the measurement frequency is the same as the natural frequency of the quantum bit is determined as the target time constant.

3. The method according to claim 2, characterized in that Before determining the corresponding plurality of second pulse waveforms according to the pulse signal waveform to be optimized and the plurality of preset time constants within the first preset range, the method further includes: Determine an initial compensation waveform according to the pulse signal waveform to be optimized and a plurality of preset time constants within a second preset range; wherein the initial compensation waveform is formed by splicing the first compensation waveform and the second compensation waveform according to the pulse time; Outputting corresponding pulse signals to the quantum bits according to a plurality of the initial compensation waveforms; Controlling the quantum state of the quantum bit to an excited state during the duration of the second compensation waveform; measuring the probability that the quantum state of the quantum bit is an excited state after the pulse time of the pulse signal corresponding to the initial compensation waveform; Determine a preset time constant when the probability that the quantum state of the quantum bit is an excited state is the maximum as an initial time constant; The first preset range is determined according to the initial time constant.

4. The method according to claim 1, characterized in that The step of determining the first pulse waveform according to the target time constant comprises: Determine that the corresponding relationship among the time constant, the distortion amplitude, the pulse amplitude and the pulse time is a first preset relationship; wherein the distortion amplitude is the amplitude of the distortion of the pulse signal waveform to be optimized after the pulse time ends due to the influence of the high-pass filter, and the pulse amplitude and the pulse time are waveform parameters of the first pulse waveform; determining a target distortion amplitude according to the target time constant; Determining a target pulse amplitude and a target pulse time of the first pulse waveform according to the target distortion amplitude, the target time constant and the first preset relationship; The first pulse waveform is determined according to the target pulse amplitude and the target pulse time.

5. The method according to claim 1, characterized in that Determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized includes: splicing the pulse signal waveform to be optimized and the first pulse waveform according to the pulse time; The spliced ​​pulse waveform is determined to be the pulse waveform of the signal of the optimized quantum signal link.

6. The method according to claim 1, characterized in that Determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized includes: Determining a second pulse waveform corresponding to the target time constant; splicing the second pulse waveform and the first pulse waveform according to pulse time; The spliced ​​pulse waveform is determined to be the pulse waveform of the signal of the optimized quantum signal link.

7. The method according to claim 1, characterized in that Determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized includes: determining at least two second pulse waveforms corresponding to the target time constant; splicing at least two of the second pulse waveforms and the first pulse waveform according to pulse time; The spliced ​​pulse waveform is determined to be the pulse waveform of the signal of the optimized quantum signal link.

8. The method of claim 1, wherein: The number of first pulse waveforms corresponding to the target time constant is at least two; and determining the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized includes: determining at least two second pulse waveforms corresponding to the target time constant; splicing the second pulse waveform and the first pulse waveform into a target pulse waveform according to the pulse time; A plurality of target pulse waveforms are spliced ​​according to pulse time to obtain a pulse waveform of a signal of an optimized quantum signal link.

9. A signal optimization device for a quantum signal link, characterized in that: include: A first determination module is used to determine a target time constant that characterizes the signal transmission characteristics of a quantum signal link according to the response of the frequency of the quantum bit to the pulse signal; wherein the quantum signal link includes a signal source, a high-pass filter, and a quantum bit on a quantum processing unit that are electrically connected in sequence through a signal transmission line; and the signal source is used to output a pulse signal that regulates the frequency of the quantum bit; A second determination module is used to determine a first pulse waveform according to the target time constant; wherein the first pulse waveform is used to compensate for the distortion of the pulse signal after the pulse ends; The third determination module is used to determine the signal of the optimized quantum signal link according to the first pulse waveform and the pulse signal waveform to be optimized.

10. A quantum signal link, characterized in that: It includes a signal source, a high-pass filter and a quantum bit on a quantum processing unit which are electrically connected in sequence through a signal transmission line; the signal source is used to output a pulse signal for regulating the frequency of the quantum bit; The pulse signal is optimized and determined by the method described in any one of claims 1-8.

11. A quantum computer, characterized in that: The waveform of the pulse signal is optimized by the method described in any one of claims 1 to 8 and the optimized pulse signal is output, or the device described in claim 9 or the quantum signal link described in claim 10 is included.

Images