Quantum state driving signal compensation method and device

Abstract

The invention belongs to the technical field of quantum computing, and particularly relates to a compensation method and device for a quantum state driving signal, and the quantum state driving signal is any microwave signal transmitted on a quantum measurement and control link. Any microwave signal is repeatedly reflected between two adjacent nodes with impedance mismatch to generate a reflected microwave signal when being transmitted on a quantum measurement and control link, and the method comprises the following steps: applying a modulation signal attached to the microwave signal on the quantum measurement and control link for compensating the reflected microwave signal, the form of the modulation signal is as follows: the phase of the modulation signal is opposite to the phase of the reflected microwave signal, the signal delay td of the modulation signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulation signal is equal to the reflectivity of the node to the microwave signal. According to the invention, through offset of the modulation signal and the reflection microwave signal, compensation of the quantum measurement and control link transmission signal is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of quantum computing, and particularly relates to a quantum state driving signal compensation method and device. BACKGROUND

[0002] The quantum computer system comprises a quantum chip system (also referred to as a quantum processor), a quantum computer measurement and control system, a quantum computer environment support system (also referred to as a dilution refrigerator), and a quantum computer operating system loaded on a classical computer. The dilution refrigerator provides different temperature zone spaces from room temperature to the lowest temperature by setting cold plates, and the different temperature zone spaces are isolated by the cold plates. The quantum chip system is arranged in the lowest temperature zone space of the dilution refrigerator, and the quantum computer measurement and control system is connected and controls the quantum chip system through a quantum measurement and control link. The quantum measurement and control link comprises a room temperature link part, a room temperature to low temperature link part (also referred to as a cross-temperature zone link), and a low temperature link part (also referred to as an ultra-low temperature link) connected in sequence. The room temperature link part is used to connect the quantum computer measurement and control system and a top flange plate of the dilution refrigerator. The room temperature to low temperature link part is used to link signals of a cold plate corresponding to the highest temperature zone space and the lowest temperature space inside the dilution refrigerator. The low temperature link part is used to link signals of the cold plate corresponding to the lowest temperature space and the quantum processor in the lowest temperature zone space.

[0003] When the quantum measurement and control link transmits a microwave signal as a quantum state driving control signal, reflection of the microwave signal will cause time delay of the microwave signal and distortion of the amplitude and phase of the microwave signal, which will seriously affect the fidelity of operations in quantum computing and quantum simulation. Therefore, it is necessary to correct the signals of the quantum measurement and control link. SUMMARY

[0004] The application aims to provide a quantum state driving signal compensation method and device to solve the problems in the prior art.

[0005] The technical scheme adopted by the application is as follows.

[0006] A quantum state driving signal compensation method, wherein the quantum state driving signal is an arbitrary microwave signal transmitted on a quantum measurement and control link. The arbitrary microwave signal repeatedly reflects between two adjacent nodes with impedance mismatch to generate a reflected microwave signal when the arbitrary microwave signal is transmitted on the quantum measurement and control link. The method comprises the following steps.

[0007] An additional modulation signal of the microwave signal is applied to the quantum measurement and control link to compensate for the reflected microwave signal, wherein the modulation signal has the following form:

[0008]

[0009] The phase of the modulation signal is opposite to the phase of the reflected microwave signal, and the signal delay t of the modulation signal isd is equal to a reflection period of the reflected microwave signal, and an amplitude A of the modulation signal is equal to a reflectivity of the node pair to the microwave signal.

[0010] The method as described above, wherein, optionally, an additional modulation signal is applied to the microwave signal via the quantum control link for compensating the reflected microwave signal, comprising:

[0011] obtaining an in-phase component signal and a quadrature component signal of the microwave signal to be modulated; obtaining a first resultant signal after the in-phase component signal and the quadrature component signal are modulated by a first digital filter respectively, and a second resultant signal after the in-phase component signal and the quadrature component signal are modulated by a second digital filter respectively; tap coefficients of the first digital filter and the second digital filter are trigonometric functions of a modulation phase; a signal delay of the modulation signal is a delay between an input signal and an output signal of the first digital filter, or a delay between an input signal and an output signal of the second digital filter; obtaining a resultant signal after the first resultant signal and the second resultant signal are mixed and modulated by a sine signal and a cosine signal based on a digital oscillation signal respectively as the modulation signal of the microwave signal.

[0012] The method as described above, wherein, optionally, the first digital filter comprises a first sub-filter and a second sub-filter, the first sub-filter is used to modulate one of the in-phase component signal and the quadrature component signal, and the second sub-filter is used to modulate the other of the in-phase component signal and the quadrature component signal; the second digital filter comprises a third sub-filter and a fourth sub-filter, the third sub-filter is used to modulate one of the in-phase component signal and the quadrature component signal, and the fourth sub-filter is used to modulate the other of the in-phase component signal and the quadrature component signal; the first sub-filter, the second sub-filter, the third sub-filter, and the fourth sub-filter are all referred to as sub-filters.

[0013] The method as described above, wherein, optionally, all the sub-filters are multi-order FIR filters with the same order.

[0014] The method as described above, wherein, optionally, tap coefficients of each order of all the sub-filters are sine trigonometric functions or cosine trigonometric functions.

[0015] The method as described above, wherein, optionally, tap coefficients of each order of all the sub-filters are 1 or 0.

[0016] The method as claimed in the preceding paragraph, wherein, optionally, the tap coefficients of different orders of each of the sub-filters have different delay modulation effects on the microwave signal to be modulated, have the same or different amplitude modulation effects on the microwave signal to be modulated, or have the same or different phase modulation effects on the microwave signal to be modulated.

[0017] The method as claimed in the preceding paragraph, wherein, optionally, the tap coefficients of the same order of all the sub-filters are partially the same and partially different.

[0018] The method as claimed in the preceding paragraph, wherein, optionally, the tap coefficients of the same order of the two sub-filters for modulating the in-phase component signal correspond to different function types, and the tap coefficients of the same order of the two sub-filters for modulating the quadrature component signal correspond to different function types.

[0019] The method as claimed in the preceding paragraph, wherein, optionally, the tap coefficients of the same order of the two sub-filters for modulating the in-phase component signal correspond to different function types and have different amplitudes, and the tap coefficients of the same order of the two sub-filters for modulating the quadrature component signal correspond to different function types and have the same amplitudes; or, the tap coefficients of the same order of the two sub-filters for modulating the in-phase component signal correspond to different function types and have the same amplitudes, and the tap coefficients of the same order of the two sub-filters for modulating the quadrature component signal correspond to different function types and have different amplitudes.

[0020] Another embodiment of the present application provides a compensation device for a quantum state driving signal, the quantum state driving signal being any microwave signal transmitted on a quantum measurement and control link, the any microwave signal repeatedly reflecting between two adjacent nodes with impedance mismatch to generate a reflected microwave signal when transmitted on the quantum measurement and control link, the device comprising:

[0021] an adjusting module configured to generate a modulation signal applied to the microwave signal on the quantum measurement and control link to compensate for the reflected microwave signal, wherein the modulation signal has the following form:

[0022]

[0023] wherein the phase of the modulation signal is opposite to the phase of the reflected microwave signal, the signal delay t of the modulation signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulation signal is equal to the reflectivity of the microwave signal at the nodes. d

[0024] ​Compared with the prior art, the application is directed to the repeated reflection of the reflected microwave signal between two adjacent nodes with impedance mismatch during the transmission of the quantum measurement and control link, and the reflected microwave signal is compensated and offset by the modulation signal attached to the microwave signal, wherein the phase of the modulation signal is opposite to the phase of the reflected microwave signal, the signal delay t of the modulation signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulation signal is equal to the reflectivity of the microwave signal of the node, so that the reflected microwave signal can be offset, and the compensation of the transmission signal of the quantum measurement and control link is realized. d BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a principle diagram of the repeated reflection of the reflected microwave signal between two adjacent nodes with impedance mismatch during the transmission of the quantum measurement and control link provided by an embodiment of the application;

[0026] Figure 2 is a compensation method diagram of the quantum state driving signal provided by an embodiment of the application;

[0027] Figure 3 is a method diagram of applying the modulation signal to the quantum measurement and control link for compensating the reflected microwave signal provided by an embodiment of the application;

[0028] Figure 4 is a diagram of a device for generating the microwave signal based on the intermediate frequency signal provided by an embodiment of the application;

[0029] Figure 5 is a diagram of a device for generating the modulation signal provided by an embodiment of the application;

[0030] Figure 6 is a diagram of a device for generating the modulation signal provided by an embodiment of the application;

[0031] Figure 7 is a signal comparison diagram of the input signal and the output signal of the XY link of the quantum bit before and after the improvement

[0032] Figure 8 is a diagram of the Rabi oscillation experimental results of the quantum measurement and control link before and after the compensation of the XY distortion DETAILED DESCRIPTION

[0033] ​The quantum control link includes an XY link and a z link. When the links transmit quantum signals, they not only cause transmission delay of the quantum signals, but also cause distortion of the quantum signals. The applicant finds that the XY link as a link for transmitting quantum state drive control signals is more difficult to ensure signal integrity due to the preparation process of the quantum processor. For example, the quantum state drive control signal is a high-frequency microwave signal, and the manufacturing packaging technology and existing through silicon vias of the preparation process of the quantum processor increase the probability of impedance mismatch of the XY link. The impedance mismatch increases the reflection of the high-frequency microwave signal, and further causes distortion of the high-frequency microwave signal, that is, distortion of the quantum logic gate signal. The distortion seriously affects the fidelity of operations in quantum computing and quantum simulation.

[0034] The amplitude and duration of the quantum state drive control signal determine the degree of change of the quantum state of the quantum bit, and the phase of the quantum state drive control signal determines the reference standard of the change of the quantum state of the quantum bit. Therefore, the calibration of the quantum state drive control signal needs to consider not only the amplitude but also the phase, and the distortion calibration is difficult.

[0035] Based on the above problems, the application provides a quantum state drive signal compensation method to compensate for the distortion of the quantum control link, so as to ensure the non-distortion of the signal transmitted by the quantum control link, and the fidelity and accuracy of operations in quantum computing and quantum simulation.

[0036] In implementation, considering the characteristics of the reflected microwave signal generated by the reflection of any microwave signal between two adjacent nodes with impedance mismatch on the quantum control link, an additional modulation signal is applied to the any microwave signal based on the characteristics of the reflected microwave signal. The phase of the modulation signal is opposite to the phase of the reflected microwave signal, the signal delay t of the modulation signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulation signal is equal to the reflectivity of the microwave signal of the node pair. Then, the compensation of the any microwave signal is realized through the cancellation of the modulation signal and the reflected signal, so as to ensure the non-distortion of the signal transmitted by the quantum control link, and the fidelity and accuracy of operations in quantum computing and quantum simulation. d In implementation, considering the characteristics of the reflected microwave signal generated by the reflection of any microwave signal between two adjacent nodes with impedance mismatch on the quantum control link, an additional modulation signal is applied to the any microwave signal based on the characteristics of the reflected microwave signal. The phase of the modulation signal is opposite to the phase of the reflected microwave signal, the signal delay t of the modulation signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulation signal is equal to the reflectivity of the microwave signal of the node pair. Then, the compensation of the any microwave signal is realized through the cancellation of the modulation signal and the reflected signal, so as to ensure the non-distortion of the signal transmitted by the quantum control link, and the fidelity and accuracy of operations in quantum computing and quantum simulation.

[0037] In order for those skilled in the art to better understand the technical solutions in the application, the technical solutions in the embodiments of the application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work should belong to the protection scope of the application. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the application, and cannot be interpreted as a limitation on the application.

[0038] Please refer to Figure 1 , Figure 1 Figure 1 is a schematic diagram of the principle of repeated reflection of any microwave signal transmitted on a quantum control link between two adjacent nodes with impedance mismatch, it can be seen that when there are only two adjacent nodes with impedance mismatch on the quantum control link, the multiple reflections of the microwave signal transmitted on the quantum control link between the two nodes, the reflected signal acts on the quantum bit with a time interval t i , the signal acting on the quantum bit for the i-th time is recorded as the i-th order signal.

[0039] Let the microwave signal input into the quantum control link be the expected signal, the transmission of the expected signal in the control link will produce the 1st order reflected signal, the 2nd order reflected signal, the 3rd order reflected signal… acting on the quantum bit; wherein, the (i+1)th order reflected signal is i times the i-th order reflected signal, wherein, Γ is the total amplitude loss coefficient of the signal when the two nodes reflect the microwave signal in turn, is the signal phase influence value when the two nodes reflect the microwave signal in turn.

[0040] The additional modulation signal of the microwave signal input into the quantum control link will also be reflected and act multiple times on the quantum bit, the modulation signal acting on the quantum bit for the first time is recorded as the 0th order modulation reflected signal, the modulation signal acting on the quantum bit for the second time is recorded as the 1st order modulation reflected signal, the modulation signal acting on the quantum bit for the third time is recorded as the 2nd order modulation reflected signal….

[0041] The signal delay of the modulation signal is equal to the reflection period of the reflected microwave signal, i.e. t d =t i , the phase of the modulation signal is opposite to the phase of the reflected microwave signal, i.e. The amplitude A of the modulation signal is equal to the reflectivity of the node to the microwave signal, i.e. A=Γ, then the 0th order modulation reflected signal can cancel the 1st order reflected signal of the expected signal, the 1st order modulation reflected signal can cancel the 2nd order reflected signal of the expected signal, the 2nd order modulation reflected signal can cancel the 3rd order reflected signal of the expected signal, and so on, and then the compensation of the microwave signal is realized by the modulation signal to cancel the reflected signal.

[0042] As an embodiment of the present application, the characteristics of the reflected signal acting on the quantum bit when there are multiple impedance mismatch nodes on the quantum control link can be accumulated and deduced based on the reflection characteristics between two adjacent impedance mismatch nodes, and a corresponding modulation signal is set. It should be noted that the reflection of the microwave signal input into the quantum control link between multiple nodes in the quantum control link causes changes in signal amplitude, signal delay and signal phase, so the form of the modulation signal provided by the present application is as follows:​

[0043] It is still suitable for situations where reflections occur between multiple nodes within a quantum measurement and control link.

[0044] Figure 2 This is a schematic diagram of a compensation method for a quantum state driving signal provided in an embodiment of this application. The quantum state driving signal is an arbitrary microwave signal transmitted on a quantum measurement and control link. When the arbitrary microwave signal is transmitted on the quantum measurement and control link, it is repeatedly reflected between two adjacent nodes with impedance mismatch, thus generating a reflected microwave signal. Figure 2 As shown, this application provides a method for compensating quantum state-driven signals, comprising:

[0045] Step S1: Apply a modulation signal to the microwave signal in the quantum measurement and control link to compensate for the reflected microwave signal, wherein the modulation signal has the following form:

[0046]

[0047] Wherein, the phase of the modulated signal is opposite to the phase of the reflected microwave signal, and the signal delay t of the modulated signal is... d The amplitude A of the modulated signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulated signal is equal to the reflectivity of the node to the microwave signal.

[0048] It should be noted that any microwave signal generally takes the following form:

[0049] s(t)=V I (t)cos(wt)+V Q (t)sin(wt)

[0050] Where V I (t) and V Q (t) represents the in-phase component and quadrature component of any microwave signal, respectively; w is the frequency of the microwave signal; wt is the initial phase of the microwave signal; modulating the microwave signal includes modulating one or a combination of the in-phase component, quadrature component, and initial phase of the microwave signal.

[0051] The above process involves applying a modulation signal based on the characteristics of the reflected microwave signal. The phase of the modulation signal is opposite to the phase of the reflected microwave signal, and the signal delay of the modulation signal is t. d The amplitude A of the modulation signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulation signal is equal to the reflectivity of the node to the microwave signal. Thus, by canceling out the modulation signal and the reflected signal, compensation for any microwave signal is achieved, so as to ensure the non-distortion of the quantum measurement and control link transmission signal and the fidelity and accuracy of the operation in quantum computing and quantum simulation.

[0052] Figure 3is a schematic diagram of a method for applying a modulation signal added to a microwave signal on a quantum measurement and control link to compensate for the reflected microwave signal provided by an embodiment of the present application, as shown in Figure 3 Applying a modulation signal on a quantum measurement and control link to compensate for the reflected microwave signal includes the following steps:

[0053] Step S201: Obtain in-phase component signals and quadrature component signals of a microwave signal to be modulated.

[0054] It should be noted that the microwave signal to be modulated can be a high-frequency microwave signal, or an intermediate frequency signal to be up-converted to obtain a high-frequency microwave signal, as long as it has a general form of any signal as shown in Figure 4 Figure 4 A schematic diagram of a device for generating a microwave signal based on an intermediate frequency signal is provided by an embodiment of the present application. In the device, a digital analog generator DAC generates an intermediate frequency signal IF, which is up-converted for the first time based on a first local oscillator signal L01 and up-converted for the second time based on a second local oscillator signal L02, and then an output signal is obtained, the frequency of the output signal being f IF +|f LO1 -f LO2 |, and a band-pass filter BPF is used to eliminate spurious signals and unwanted sidebands in the process. As can be seen, the output signal after the two up-conversions is frequency-shifted relative to the intermediate frequency signal, so the intermediate frequency signal can be used to represent the microwave signal to be modulated.

[0055] Step S202: Obtain a first synthesized signal after the in-phase component signals and the quadrature component signals are modulated by a first digital filter, and a second synthesized signal after the in-phase component signals and the quadrature component signals are modulated by a second digital filter; the tap coefficients of the first digital filter and the second digital filter are trigonometric functions of the modulation phase; the signal delay of the modulation signal is the delay between the input signal and the output signal of the first digital filter, or the delay between the input signal and the output signal of the second digital filter.

[0056] It can be understood that a digital filter can generally be represented by a linear constant coefficient difference equation as follows:

[0057]

[0058] Where x(n) is the input signal of the digital filter, y(n) is the output signal of the digital filter, variable n is an integer value representing a discrete instance, and n can be converted to a continuous time variable t using t=nTs. M is the total order of the filter, b m is the tap coefficient of the mth order of the filter, a k is the tap coefficient of the kth order of the filter.​m is a feedforward tap coefficient, a k is a feedback tap coefficient.

[0059] When a k = 0, the digital filter represented by the above linear constant coefficient difference equation is a FIR filter, also called a forward feedback filter, wherein the FIR (Finite Impulse Response) filter, i.e., the finite-length unit impulse response filter, is also called a non-recursive filter.

[0060] The linear constant coefficient difference equation of the FIR filter is:

[0061]

[0062] The above formula represents the delay time step m between the input signal and the output signal, so the digital filter has the function of adjusting the signal delay. The t d = n d Ts can be converted into the continuous-time variable t d of m equal to n d , that is: That is, the input signal and the output signal of the digital filter have a signal delay of t d .

[0063] Step S203: Obtain the synthesized signal after the first synthesized signal and the second synthesized signal are mixed and modulated by the sine signal and the cosine signal based on the digital oscillation signal respectively as the modulation signal of the microwave signal.

[0064] Based on the process, the delay modulation of the digital filter on any quadrature decomposition signal and the digital oscillation signal are combined to obtain a modulation signal that can modulate the signal delay, amplitude and phase of any quadrature decomposition signal.

[0065] As an embodiment of the present application, Figure 5 is a schematic diagram of a modulation signal generation device provided by an embodiment of the present application; as Figure 5 shown, the device comprises a first digital filter, a first signal synthesis device, a second digital filter, a second signal synthesis device, a digital controlled oscillator, a first mixer, a second mixer and a third signal synthesis device.

[0066] The input end of the first digital filter receives the in-phase component signal and the quadrature component signal for respectively performing first modulation on the in-phase component signal and the quadrature component signal; the input end of the first signal synthesizing device is connected with the first digital filter for synthesizing the output signal corresponding to the in-phase component signal and the output signal of the quadrature component signal output by the first digital filter to obtain a first synthesized signal; the input end of the second digital filter receives the in-phase component signal and the quadrature component signal for respectively performing second modulation on the in-phase component signal and the quadrature component signal; the input end of the second signal synthesizing device is connected with the second digital filter for synthesizing the output signal corresponding to the in-phase component signal and the output signal of the quadrature component signal output by the second digital filter to obtain a second synthesized signal; the numerically controlled oscillator is used for generating a sine signal and a cosine signal; the input end of the first mixer is connected with the output end of the first signal synthesizing device and one output end of the numerically controlled oscillator; the input end of the second mixer is connected with the output end of the second signal synthesizing device and the other output end of the numerically controlled oscillator; the input end of the third signal synthesizing device is connected with the output ends of the first mixer and the second mixer. The tap coefficients of the first digital filter and the tap coefficients of the second digital filter are trigonometric functions of modulation phase.

[0067] The principle of the above device for generating a modulation signal is as follows:

[0068] The tap coefficients of the first digital filter and the second digital filter are trigonometric functions of modulation phase, and the trigonometric function is a sine trigonometric function, a cosine trigonometric function or a combination of the two. Exemplarily, the tap coefficients of the first digital filter are Then Or Or The tap coefficients of the second digital filter are Then Or Or Wherein, is a modulation phase. The tap coefficients of the first digital filter and the second digital filter are trigonometric functions of the modulation phase, that is, the input signal is multiplied by the trigonometric functions, and the subterms of the first and second synthesized signals obtained are all the products of the signal delay signal and the trigonometric functions. The first and second synthesized signals obtained by digital filter modulation are all the products of the signal delay signal and the trigonometric functions, and the first and second synthesized signals are mixed with the sine or cosine oscillation signal to obtain the total synthesized signal (i.e. the modulation signal). Each subterm of the total synthesized signal is the product of the signal delay signal and two trigonometric functions; according to the trigonometric function transformation theory in mathematics, it can be obtained that the total synthesized signal only has the differences of amplitude, signal delay and phase compared with the general form of the microwave signal, that is, the digital oscillation signal generated by the digital filter and the digital controlled oscillator modulates one of the signal delay, phase and amplitude of the arbitrary microwave signal or a combination thereof.

[0069] It should be noted that the above-mentioned sine signal and cosine signal of the digital oscillation signal are mixed and modulated with the first and second synthesized signals respectively, which is not unique, and the sine signal of the digital oscillation signal can also be mixed and modulated with the second synthesized signal, and the cosine signal of the digital oscillation signal can be mixed and modulated with the first synthesized signal. As long as the whole can realize the effect of modulating one of the signal delay, phase and amplitude of the arbitrary microwave signal or a combination thereof based on the digital filter and the digital controlled oscillator.

[0070] As an embodiment of the present application, as shown in Figure 6 the first digital filter includes a first sub-filter and a second sub-filter, the first sub-filter is used to modulate one of the in-phase component signal and the quadrature component signal, and the second sub-filter is used to modulate the other of the in-phase component signal and the quadrature component signal; the second digital filter includes a third sub-filter and a fourth sub-filter, the third sub-filter is used to modulate one of the in-phase component signal and the quadrature component signal, and the fourth sub-filter is used to modulate the other of the in-phase component signal and the quadrature component signal; the first sub-filter, the second sub-filter, the third sub-filter and the fourth sub-filter are all recorded as sub-filters.

[0071] The sub-filter in the first digital filter for modulating the in-phase component signal is recorded as the first sub-filter, and the tap coefficient of the m (m = n d ) order of the first sub-filter is recorded as The sub-filter in the first digital filter for modulating the quadrature component signal is recorded as the second sub-filter, and the tap coefficient of the m (m = n d ) order of the second sub-filter is recorded as

[0072] The sub-filter in the second digital filter modulating the in-phase component signal is referred to as a third sub-filter, and the tap coefficient of the m (m = n d ) order is recorded as The sub-filter in the second digital filter modulating the quadrature-phase component signal is referred to as a fourth sub-filter, and the tap coefficient of the m (m = n d ) order is recorded as The first sub-filter, the second sub-filter, the third sub-filter, and the fourth sub-filter are all referred to as sub-filters. All the sub-filters are multi-order filters with the same order.

[0073] The modulation signal corresponding to the above process is:

[0074]

[0075] In the example, the sine signal generated by the numerically controlled oscillator is used to modulate the first synthesized signal, and the cosine signal generated by the numerically controlled oscillator is used to modulate the second synthesized signal. Then:

[0076] The corresponding modulation signal is:

[0077]

[0078] In the above formula, when and are sine and cosine trigonometric functions, the modulation signal can be simplified to contain two sub-terms, the first sub-term is the product of the in-phase component signal and the first trigonometric function, and the second sub-term is the product of the quadrature-phase component signal and the second trigonometric function, wherein the first trigonometric function and the second trigonometric function are orthogonal. And and The specific values of and are not limited, as long as the above effects can be achieved.

[0079] The above embodiments introduce an exemplary process of generating a modulation signal based on sine and cosine signals generated by a mathematical filter and a numerically controlled oscillator.

[0080] It should be noted that the first digital filter and the second digital filter both include sub-filters corresponding to the in-phase component signal and the quadrature-phase component signal to modulate the in-phase component signal and the quadrature-phase component signal, respectively. In specific implementation, the sub-filters corresponding to the in-phase component signal and the quadrature-phase component signal in the first digital filter can be physically presented in the form of different channels of the first digital filter, or can be separately set.

[0081] As an embodiment of the present application, the tap coefficients of the same order of the two sub-filters for modulating the in-phase component signal correspond to different function types, and the tap coefficients of the same order of the two sub-filters for modulating the quadrature component signal correspond to different function types.

[0082] For example, the tap coefficients of the first sub-filter are set as The tap coefficients of the second sub-filter are set as The tap coefficients of the third sub-filter are set as The tap coefficients of the fourth sub-filter are set as For another simplification, the tap coefficients of the first sub-filter are set as Then,

[0083]

[0084] As an embodiment of the present application, the tap coefficients of the same order of the two sub-filters for modulating the in-phase component signal correspond to different function types and different amplitudes of the functions, and the tap coefficients of the same order of the two sub-filters for modulating the quadrature component signal correspond to different function types and same amplitudes of the functions; or, the tap coefficients of the same order of the two sub-filters for modulating the in-phase component signal correspond to different function types and same amplitudes of the functions, and the tap coefficients of the same order of the two sub-filters for modulating the quadrature component signal correspond to different function types and different amplitudes of the functions. For example, the tap coefficients of the first filter are set as The tap coefficients of the second filter are set as The tap coefficients of the third filter are set as The tap coefficients of the fourth filter are set as Then,

[0085]

[0086] This embodiment is only for signal delay modulation of an arbitrary microwave signal.

[0087] As an embodiment of the present application, all the sub-filters are multi-order filters with the same order. The tap coefficients of different orders of each sub-filter have different delay modulation effects on the microwave signal to be modulated, and have the same or different amplitude modulation effects on the microwave signal to be modulated, and have the same or different phase modulation effects on the microwave signal to be modulated. For example, for different orders of each digital filter, for example, The corresponding signal delay is t d1 ; The corresponding signal delay is t d2 . For another example, the amplitude modulation effects on the microwave signal to be modulated are the same or different, i.e. They can be the same or different.

[0088] It should be noted that all the sub-filters are integrated together and each channel corresponds to a sub-filter, and the setting of the tap coefficients of the same order of the plurality of sub-filters can be set as required by the above-mentioned embodiments, and those skilled in the art can set as required; the setting of the tap coefficients of different orders of the same sub-filter can be selected and set according to the required signal delay. Exemplarily, for a sub-filter of M order, one of the m order (m = n d ) tap coefficients can be set as and the other tap coefficients are all set to 0.

[0089] As an embodiment of the present application, the digital-analog generator DAC of Figure 4 is integrated with the improved digital filter and numerically controlled oscillator of the above-mentioned embodiments to generate a quantum state driving control signal (i.e. the RF signal in the figure), aiming to generate a compensation modulation signal from the source of the intermediate frequency signal IF, so that the reflection signal (also known as the distortion signal) generated in the transmission process of the microwave signal generated based on the intermediate frequency signal is compensated by the modulation signal. Referring to Figure 7 and Figure 8 , Figure 7 is a signal comparison diagram of the input signal and the output signal of the XY link of the quantum bit before and after improvement, wherein the output signal is observed by the quantum bit receiving end. The four subgraphs from top to bottom in the figure are respectively the input signal without the added modulation signal, the output signal observed by the quantum bit receiving end corresponding to the input signal; the input signal with the added modulation signal, and the output signal observed by the quantum bit receiving end corresponding to the input signal; in the fourth subgraph, the solid black line represents the signal after the modulation signal and the distortion signal are offset, the dashed line above the black solid line represents the distortion signal, and the dashed line below the black solid line represents the modulation signal. Figure 8 is a schematic diagram of the Rabi oscillation experimental results of the XY distortion uncompensated and compensated quantum bit of the quantum measurement and control link, Figure 8 (a) is the Rabi oscillation experimental results of the XY distortion uncompensated quantum measurement and control link, which is an irregular herringbone pattern; Figure 8 (b) is the Rabi oscillation experimental results of the XY distortion compensated quantum measurement and control link, which is a regular herringbone pattern.

[0090] Based on the same inventive concept, the present application also provides a compensation device for a quantum state driving signal, the quantum state driving signal being any microwave signal transmitted on a quantum measurement and control link, and the any microwave signal repeatedly reflects between two adjacent nodes with impedance mismatch to generate a reflected microwave signal when transmitted on the quantum measurement and control link, the device comprising:

[0091] An adjusting module configured to generate a modulation signal applied to the quantum control link to compensate for the reflected microwave signal, wherein the modulation signal has the form:

[0092]

[0093] wherein the phase of the modulation signal is opposite to the phase of the reflected microwave signal, the signal delay t of the modulation signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulation signal is equal to the reflectivity of the node pair for the microwave signal. d

[0094] The systems, apparatuses, modules or units illustrated in the above embodiments can be specifically implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer, and the specific form of the computer can be a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an e-mail device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0095] In a typical configuration, a computer includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0096] The memory can include non-persistent memory in the computer readable medium, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM), electrically erasable read-only memory (EEPROM), or flash memory. The memory is an example of computer readable media.

[0097] Computer readable media includes permanent and non-permanent, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD), or other optical storage, magnetic cassette, disk storage, quantum memory, graphene-based storage medium, or other magnetic storage device, or any other non-transmission medium that can be used to store information accessible to a computing device. According to the definition herein, computer readable media does not include transitory computer readable media, such as modulated data signals and carriers.

[0098] ​It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0099] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0100] The terminology used in one or more embodiments of this specification is for the purpose of describing particular embodiments only and is not intended to limit the one or more embodiments of this specification. The singular forms “a,” “described,” and “the” used in one or more embodiments of this specification and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items. It should be understood that although the terms first, second, third, etc., may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of one or more embodiments of this specification, and similarly, second information may also be referred to as first information. Depending on the context, the word “if” as used herein may be interpreted as “when,” “when,” or “in response to a determination.” The above descriptions are merely preferred embodiments of one or more embodiments of this specification and are not intended to limit the one or more embodiments of this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification should be included within the scope of protection of one or more embodiments of this specification.

[0101] The above detailed description of the structure, features and effects of the present application is based on the embodiments shown in the drawings. The above description is only the preferred embodiments of the present application, but the present application is not limited to the embodiments shown in the drawings. Any changes or modifications made in accordance with the concept of the present application, or equivalent embodiments with equivalent changes, are still within the scope of the present application.

Claims

1. A method for compensating quantum state-driven signals, characterized in that, The quantum state driving signal is an arbitrary microwave signal transmitted on the quantum measurement and control link. When this arbitrary microwave signal is transmitted on the quantum measurement and control link, it is repeatedly reflected between two adjacent nodes with impedance mismatch, generating a reflected microwave signal. The method includes: A modulation signal is applied to the microwave signal in the quantum telemetry and control link to compensate for the reflected microwave signal, wherein the modulation signal has the following form: Wherein, the phase of the modulated signal is opposite to the phase of the reflected microwave signal, and the signal delay t of the modulated signal is... d The amplitude A of the modulated signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulated signal is equal to the reflectivity of the node to the microwave signal.

2. The method according to claim 1, characterized in that, Applying a modulation signal to the microwave signal in the quantum measurement and control link to compensate for the reflected microwave signal includes: Acquire the in-phase and quadrature component signals of the microwave signal to be modulated; A first composite signal is obtained by modulating the in-phase component signal and the quadrature component signal respectively through a first digital filter, and a second composite signal is obtained by modulating the in-phase component signal and the quadrature component signal respectively through a second digital filter; the tap coefficients of the first digital filter and the second digital filter are trigonometric functions of the modulation phase; the signal delay of the modulated signal is the delay between the input signal and the output signal of the first digital filter, or the delay between the input signal and the output signal of the second digital filter; The composite signal obtained by mixing and modulating the first composite signal and the second composite signal with the sine and cosine signals based on the digital oscillation signal is used as the modulation signal of the microwave signal.

3. The method according to claim 2, characterized in that, The first digital filter includes a first sub-filter and a second sub-filter. The first sub-filter is used to modulate one of the in-phase component signal and the quadrature component signal, and the second sub-filter is used to modulate the other of the in-phase component signal and the quadrature component signal. The second digital filter includes a third sub-filter and a fourth sub-filter. The third sub-filter is used to modulate one of the in-phase component signal and the quadrature component signal, and the fourth sub-filter is used to modulate the other of the in-phase component signal and the quadrature component signal. The first sub-filter, the second sub-filter, the third sub-filter, and the fourth sub-filter are all referred to as sub-filters.

4. The method according to claim 3, characterized in that, All of the sub-filters are multi-order FIR filters of the same order.

5. The method according to claim 4, characterized in that, The tap coefficients of each order of all the sub-filters are sine or cosine trigonometric functions.

6. The method according to claim 5, characterized in that, The tap coefficients for each order of all the sub-filters are 1 or 0.

7. The method according to any one of claims 4-6, characterized in that, The different order tap coefficients of each sub-filter have different effects on the delay modulation of the microwave signal to be modulated, the same or different effects on the amplitude modulation of the microwave signal to be modulated, and the same or different effects on the phase modulation of the microwave signal to be modulated.

8. The method according to claim 5, characterized in that, All the sub-filters of the same order have tap coefficients that are partially the same and partially different.

9. The method according to claim 5, characterized in that, The tap coefficients of the same order in the two sub-filters used to modulate the in-phase component signal have different function types, and the tap coefficients of the same order in the two sub-filters used to modulate the quadrature component signal have different function types.

10. The method according to claim 5, characterized in that, The tap coefficients of the same order used to modulate the in-phase component signal have different function types and different function amplitudes, and the tap coefficients of the same order used to modulate the quadrature component signal have different function types and the same function amplitudes. Alternatively, the tap coefficients of the same order of the two sub-filters used to modulate the in-phase component signal correspond to different function types and have the same function amplitude, and the tap coefficients of the same order of the two sub-filters used to modulate the quadrature component signal correspond to different function types and have different function amplitudes.

11. A compensation device for quantum state-driven signals, characterized in that, The quantum state driving signal is an arbitrary microwave signal transmitted on the quantum measurement and control link. When this arbitrary microwave signal is transmitted on the quantum measurement and control link, it is repeatedly reflected between two adjacent nodes with impedance mismatch, generating a reflected microwave signal. The device includes: An adjustment module is used to generate a modulation signal applied to the microwave signal attached to the quantum measurement and control link to compensate for the reflected microwave signal, wherein the modulation signal has the following form: Wherein, the phase of the modulated signal is opposite to the phase of the reflected microwave signal, and the signal delay t of the modulated signal is... d The amplitude A of the modulated signal is equal to the reflection period of the reflected microwave signal, and the amplitude A of the modulated signal is equal to the reflectivity of the node to the microwave signal.

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