Device and method for measuring quantum chip state

Abstract

The present invention provides a device and method for measuring the state of a quantum chip, which mainly relates to the field of quantum computing technology. The measuring device includes: a signal emission module, which is used to emit a radio frequency signal to a quantum chip inside a dilution refrigerator; a signal processing module, which is used to perform signal transformation on a radio frequency reflection signal formed by reflection of the quantum chip to obtain a spectrum of the radio frequency reflection signal; a matched filter module, which is used to filter the spectrum of the radio frequency reflection signal using a matched filter coefficient to obtain a spectrum corresponding to the output signal; and a signal analysis module, which is used to perform spectrum analysis on the spectrum corresponding to the output signal to obtain the state information of the quantum chip.

Description

Technical Field

[0001] The present invention relates to the field of quantum computing technology, and more specifically, to a device and method for measuring the state of a quantum chip. Background Art

[0002] In quantum computing, radio frequency reflection measurement technology, as a fast and non-invasive measurement method, extracts charge state information in quantum dots by obtaining the reflection coefficient, providing strong support for the research and application of quantum computing.

[0003] Traditional RF reflection measurement technologies mostly use homodyne demodulation to demodulate RF reflection signals to extract the reflection coefficient of the chip under test, and then obtain the state information of the bit (quantum dot). However, since the RF reflection signal in the quantum chip is relatively weak and easily interfered by environmental noise, the current RF reflection measurement technology has low signal extraction accuracy in a high-noise environment. In addition, current RF reflection measurement technology usually uses hardware such as mixers and filters to achieve frequency conversion and filtering of signals, making the system design not simple and flexible enough. Summary of the invention

[0004] In view of this, the present invention provides a device and method for measuring the state of a quantum chip.

[0005] One aspect of the present invention provides a device for measuring the state of a quantum chip, wherein the measuring device includes: a signal emission module, the signal emission module is used to emit a radio frequency signal to a quantum chip inside a dilution refrigerator; a signal processing module, the signal processing module is used to perform signal transformation on a radio frequency reflection signal formed by reflection of the quantum chip to obtain a spectrum of the radio frequency reflection signal; a matched filtering module, the matched filtering module is used to filter the spectrum of the radio frequency reflection signal using a matched filtering coefficient to obtain a spectrum corresponding to an output signal; and a signal analysis module, the signal analysis module is used to perform spectrum analysis on the spectrum corresponding to the output signal to obtain state information of the quantum chip.

[0006] According to an embodiment of the present invention, the signal analysis module is configured to: perform spectrum analysis on the spectrum corresponding to the output signal to obtain spectrum information of the output signal; extract the amplitude of the output signal and the phase of the output signal from the spectrum information of the output signal; calculate the modulus of the reflection coefficient based on the amplitude of the RF signal, the link gain and the amplitude of the output signal; calculate the amplitude angle of the reflection coefficient based on the initial phase of the RF signal and the phase of the output signal; obtain the state information of the quantum chip based on the modulus of the reflection coefficient and the amplitude angle of the reflection coefficient.

[0007] According to an embodiment of the present invention, the above-mentioned matched filtering module is configured to: determine the above-mentioned matched filtering coefficient based on the spectrum information and phase delay coefficient of the above-mentioned radio frequency signal; and obtain the above-mentioned spectrum corresponding to the output signal based on the above-mentioned matched filtering coefficient and the spectrum of the above-mentioned radio frequency reflection signal.

[0008] According to an embodiment of the present invention, the signal output module includes a signal generating unit and an attenuator unit, wherein the signal generating unit is configured to generate an initial RF signal, and the attenuator unit is used to adjust the amplitude of the initial RF signal to obtain the RF signal.

[0009] According to an embodiment of the present invention, the measurement device further includes a control transformation module, wherein the control transformation module is configured to be connected to the signal output module; the control transformation module is used to control the signal amplitude, frequency and initial phase of the initial RF signal.

[0010] According to an embodiment of the present invention, the above-mentioned control transformation module is also configured to be connected to the above-mentioned matched filtering module; the above-mentioned control transformation module is also used to determine the above-mentioned matched filtering coefficient based on the spectrum information of the above-mentioned radio frequency signal and the above-mentioned phase delay coefficient, and configure the above-mentioned matched filtering coefficient in the above-mentioned matched filtering module.

[0011] According to an embodiment of the present invention, the above-mentioned signal processing module includes an analog-to-digital conversion unit and a signal conversion unit, wherein the above-mentioned analog-to-digital conversion unit is configured to collect and analog-to-digital convert the above-mentioned radio frequency reflection signal in response to receiving the above-mentioned radio frequency reflection signal to obtain a digital signal of the radio frequency reflection signal; and the above-mentioned signal conversion unit is configured to perform Fourier transform processing on the digital signal of the above-mentioned radio frequency reflection signal to obtain the frequency spectrum of the above-mentioned radio frequency reflection signal.

[0012] According to an embodiment of the present invention, the matched filtering module is further configured to: determine a unit impulse response function based on the delay time of the RF signal and the RF reflection signal; and perform convolution processing on the RF reflection signal using the unit impulse response function to obtain the output signal.

[0013] According to an embodiment of the present invention, the signal analysis module is further configured to: perform Fourier transform on the output signal to obtain the spectrum corresponding to the output signal; perform spectrum analysis on the spectrum corresponding to the output signal to obtain the state information of the quantum chip; the control transformation module is further configured to: determine the unit impulse response function based on the time domain signal of the RF signal and the delay time of the RF reflection signal, and configure the unit impulse response function in the matched filtering module.

[0014] Another aspect of the present invention provides a method for measuring the state of a quantum chip, which is applied to the above-mentioned device for measuring the state of a quantum chip. The above-mentioned measurement method includes: obtaining a radio frequency signal in response to a measurement request for the above-mentioned quantum chip; emitting the above-mentioned radio frequency signal to the quantum chip inside the dilution refrigerator; performing signal transformation on the radio frequency reflection signal formed by reflection of the above-mentioned quantum chip to obtain the spectrum of the radio frequency reflection signal; filtering the spectrum of the above-mentioned radio frequency reflection signal using a matched filter coefficient to obtain a spectrum corresponding to the output signal; and performing spectrum analysis on the above-mentioned spectrum corresponding to the output signal to obtain the state information of the above-mentioned quantum chip.

[0015] According to an embodiment of the present invention, the spectrum signal is filtered by the matched filter coefficient configured in the matched filter module, thereby enhancing the correlation between the RF reflection signal and the reference signal, effectively improving the distinction between the RF reflection signal and noise and interference, so that the measurement device provided by the present invention can better extract the state information of the quantum chip under the background of high noise and interference. In addition, since the signal amplitude, signal frequency and initial phase of the RF signal are adjustable, and no hardware devices such as mixers and filters are required, when computing resources are limited, especially when there is a priori knowledge of the characteristics of the measured signal, the calculation process can be simplified, and it can be flexibly configured according to different quantum chips and experimental requirements, which improves the adaptability and versatility of embedded systems or low-power scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0017] Figure 1 A schematic diagram of a device for measuring the state of a quantum chip according to an embodiment of the present invention is shown.

[0018] Figure 2 A specific structural schematic diagram of a device for measuring the state of a quantum chip according to an embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram showing the output result of matched filtering of a radio frequency reflection signal according to a specific embodiment of the present invention is shown.

[0020] Figure 4 A partial schematic diagram shows an output result of matched filtering of a radio frequency reflection signal according to a specific embodiment of the present invention.

[0021] Figure 5 The diagram shows the variation of the envelope of the output signal over time when matched filtering is performed on the radio frequency reflection signal according to a specific embodiment of the present invention.

[0022] Figure 6A schematic diagram showing the specific structure of a device for measuring the state of a quantum chip according to another embodiment of the present invention is shown.

[0023] Figure 7 A flow chart of a method for measuring the state of a quantum chip according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0024] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0025] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0026] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0027] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0028] In quantum computing, radio frequency reflection measurement technology, as a fast and non-invasive measurement method, extracts charge state information in quantum dots by obtaining the reflection coefficient, providing strong support for the research and application of quantum computing.

[0029] Traditional RF reflection measurement technologies mostly use homodyne demodulation to demodulate the RF reflection signal to extract the reflection coefficient of the chip under test, such as the amplitude and phase of the reflection coefficient, and then obtain the state information of the bit (quantum dot).

[0030] However, because the RF reflection signal in the quantum chip is relatively weak and easily interfered by environmental noise, the existing RF reflection measurement technology is difficult to ensure accurate signal extraction in a high-noise environment. In addition, the current RF reflection measurement technology usually uses hardware such as mixers and filters to achieve signal frequency conversion and filtering, making the system design not simple and flexible enough.

[0031] In view of this, the embodiment of the present invention filters the spectrum signal through the matched filter coefficient configured in the matched filter module, thereby enhancing the correlation between the RF reflection signal and the reference signal, effectively improving the distinction between the RF reflection signal and noise and interference, so that the measurement device provided by the present invention can better extract the state information of the quantum chip under the background of high noise and interference. In addition, since the signal amplitude, signal frequency and initial phase of the RF signal are adjustable, and no hardware devices such as mixers and filters are required, when computing resources are limited, especially when there is a priori knowledge of the characteristics of the measured signal, the calculation process can be simplified, and it can be flexibly configured according to different quantum chips and experimental requirements, which improves the adaptability and versatility of embedded systems or low-power scenarios.

[0032] Specifically, an embodiment of the present invention provides a device for measuring the state of a quantum chip, wherein the measuring device includes: a signal emission module, used to emit a radio frequency signal to a quantum chip inside a dilution refrigerator; a signal processing module, used to perform signal transformation on a radio frequency reflection signal formed by reflection of the quantum chip to obtain a spectrum of the radio frequency reflection signal; a matched filtering module, used to filter the spectrum of the radio frequency reflection signal using a matched filtering coefficient to obtain a spectrum corresponding to the output signal; and a signal analysis module, used to perform spectrum analysis on the spectrum corresponding to the output signal to obtain state information of the quantum chip.

[0033] Figure 1 A schematic diagram of a device for measuring the state of a quantum chip according to an embodiment of the present invention is shown.

[0034] like Figure 1 As shown, the measuring device includes a signal output module 1, a signal processing module 2, a matched filtering module 3, and a signal analysis module 4.

[0035] Among them, the signal output end of the signal output module 1 is connected to the signal input end of the quantum chip, the signal input end of the signal processing module 2 is connected to the signal output end of the quantum chip, the signal output end of the signal processing module 2 is connected to the signal input end of the matching filter module 3, and the signal output end of the matching filter module 3 is connected to the signal input end of the signal analysis module 4.

[0036] According to an embodiment of the present invention, the signal output module 1 can be used to generate a radio frequency signal and output the radio frequency signal to a quantum chip inside a dilution refrigerator, wherein the signal amplitude, signal frequency and initial phase of the radio frequency signal are all adjustable.

[0037] According to an embodiment of the present invention, the signal processing module 2 can be used to perform signal conversion on the RF reflection signal formed by the reflection of the quantum chip to obtain the spectrum of the RF reflection signal. Specifically, the signal processing module 2 samples and quantizes the RF reflection signal actually received, and performs signal conversion on it. Among them, the RF reflection signal actually received by the signal processing module 2 includes a RF reflection sub-signal and a noise sub-signal. Therefore, the information carried by the RF reflection signal includes the reflection coefficient of the quantum chip, the link gain, and the link noise.

[0038] According to an embodiment of the present invention, the matched filtering module 3 may be used to filter the spectrum of the radio frequency reflection signal using the matched filtering coefficient to obtain a spectrum corresponding to the output signal.

[0039] According to an embodiment of the present invention, the signal analysis module 4 can be used to perform spectrum analysis on the spectrum corresponding to the output signal, obtain the signal amplitude of the output signal and the corresponding phase information, and based on the signal amplitude of the output signal and the corresponding phase information, obtain the reflection coefficient modulus and reflection coefficient angle of the quantum chip, thereby obtaining the state information of the quantum chip.

[0040] According to an embodiment of the present invention, Figure 1 As shown, the measurement device of the quantum chip may further include a control transformation module 5, wherein the control transformation module 5 is connected to the signal output module 1 and the matched filter module 3 respectively. The control transformation module may be configured to control and adjust the signal amplitude, frequency and initial phase of the initial radio frequency signal generated by the signal output module 1. The control transformation module may also be configured to calculate the matched filter coefficient based on the spectrum information and phase delay coefficient of the radio frequency signal in advance, and store the matched filter coefficient in the matched filter module 3 to reduce the amount of calculation in the calculation process.

[0041] Based on this, the embodiment of the present invention filters the spectrum signal through the matching filter coefficient configured in the matching filter module, thereby enhancing the correlation between the RF reflection signal and the reference signal, effectively improving the distinction between the RF reflection signal and noise and interference, so that the measurement device provided by the present invention can better extract the state information of the quantum chip under the background of high noise and interference. In addition, since the signal amplitude, signal frequency and initial phase of the RF signal are adjustable, and no hardware devices such as mixers and filters are required, when computing resources are limited, especially when there is a priori knowledge of the characteristics of the measured signal, the calculation process can be simplified, and it can be flexibly configured according to different quantum chips and experimental requirements, which improves the adaptability and versatility of embedded systems or low-power scenarios.

[0042] Figure 2 A specific structural schematic diagram of a device for measuring the state of a quantum chip according to an embodiment of the present invention is shown.

[0043] like Figure 2 As shown, the signal output module 1 may include a signal generating unit 101 and an attenuation unit 102, wherein the output end of the signal generating unit 101 is connected to the input end of the attenuator unit 102, and the output end of the attenuator unit 102 is connected to the signal input end of the quantum chip inside the dilution refrigerator.

[0044] According to an embodiment of the present invention, the signal generating unit 101 can be used to generate an initial radio frequency signal, the signal amplitude of the initial radio frequency signal is adjusted by the attenuator unit 102 to obtain a radio frequency signal, and the radio frequency signal is incident on the quantum chip inside the dilution refrigerator. The expression of the radio frequency signal is as follows:

[0045] (1);

[0046] In the formula, represents the radio frequency signal, A represents the signal amplitude of the radio frequency signal, represents the resonant frequency of the quantum chip, t represents time, Indicates the initial phase of the RF signal, where the initial phase can be set to 0.

[0047] According to an embodiment of the present invention, the RF signal is reflected by the quantum chip to form a RF reflection signal. Since noise is contained in the signal transmission process, the RF reflection signal actually received by the signal processing module 2 includes a RF reflection sub-signal and a noise sub-signal. Specifically, the expression of the RF reflection signal is as follows:

[0048] (2);

[0049] (3);

[0050] In the formula, represents the radio frequency reflection sub-signal; represents the reflection coefficient of the quantum chip, where the reflection coefficient is a complex number including the modulus and the phase angle; g represents the link gain, which is a known constant; Represents the RF reflected signal, represents the noise sub-signal.

[0051] like Figure 2 As shown, the signal processing module 2 may include an analog-to-digital conversion unit 201 and a signal conversion unit 202, wherein the input end of the analog-to-digital conversion unit 201 is connected to the signal output end of the quantum chip inside the dilution refrigerator, the output end of the analog-to-digital conversion unit 201 is connected to the input end of the signal conversion unit 202, and the output end of the signal conversion unit 202 is connected to the input end of the matched filtering module 3.

[0052] According to the embodiment of the present invention, the analog-to-digital conversion unit 201 first samples and quantizes the radio frequency reflection signal, and converts the radio frequency reflection signal into Convert from analog to digital Based on the digital signal of the collected RF reflection signal by the signal conversion unit 202 Perform fast Fourier transform to convert the digital signal of the RF reflection signal from the time domain signal to the frequency domain signal, so as to perform spectrum analysis on the frequency domain signal of the RF reflection signal to identify the spectrum signal corresponding to the RF reflection signal .

[0053] According to an embodiment of the present invention, the matched filter module 3 filters the spectrum of the radio frequency reflection signal by matching the filter coefficient to obtain a spectrum corresponding to the output signal. The matched filter coefficient can be calculated based on the spectrum information corresponding to the radio frequency signal and the phase delay coefficient. The phase delay coefficient can be determined based on the resonant frequency and the filter frequency of the quantum chip. Specifically, the expression of the matched filter coefficient is as follows:

[0054] (4);

[0055] In the formula, represents the matched filter coefficient; A conjugate signal representing a spectrum signal corresponding to the radio frequency signal; represents the phase delay coefficient, where represents the time constant, , n is a positive integer, represents the resonant frequency of the quantum chip; f represents the filtering frequency.

[0056] According to an embodiment of the present invention, when the system is not configured with the control transformation module 5, the matched filter coefficient can be determined by the matched filter module 3; when the system is configured with the control transformation module 5, the matched filter coefficient can be determined by the control transformation module 5 and pre-stored in the matched filter module 3 so as to be quickly called during real-time processing.

[0057] According to an embodiment of the present invention, the expression of the spectrum signal corresponding to the output signal obtained after filtering the radio frequency reflection signal is as follows:

[0058] (5);

[0059] In the formula, Represents the spectrum signal corresponding to the output signal.

[0060] like Figure 2 As shown, the signal analysis module 4 includes a spectrum analysis unit 401 , wherein an input end of the spectrum analysis unit 401 is connected to a signal output end of the matched filter module 3 .

[0061] According to an embodiment of the present invention, the spectrum analysis unit 401 can be used to perform spectrum analysis on the spectrum signal corresponding to the output signal to obtain the spectrum information of the output signal, wherein the spectrum information of the output signal may include the signal amplitude spectrum and phase spectrum of the output signal. The amplitude spectrum can be used to display the intensity of the output signal at different signal frequencies, and the phase spectrum can be used to display the phase delay of the output signal at different signal frequencies.

[0062] According to an embodiment of the present invention, the modulus of the reflection coefficient can be calculated based on the amplitude of the RF signal, the link gain, and the amplitude of the output signal. The modulus of the reflection coefficient is used to represent the amplitude attenuation value of the output signal. Specifically, the modulus expression of the reflection coefficient is as follows:

[0063] (6);

[0064] In the formula, represents the modulus of the reflection coefficient, Represents the signal amplitude of the output signal at frequency f.

[0065] According to an embodiment of the present invention, based on the initial phase of the RF signal and the phase of the output signal, the amplitude of the reflection coefficient can be calculated. The amplitude of the reflection coefficient is used to represent the phase change value of the output signal. Specifically, the initial phase of the RF signal can be deducted from the phase of the output signal to obtain the amplitude of the reflection coefficient. The amplitude expression of the reflection coefficient is as follows:

[0066] (7);

[0067] In the formula, represents the argument of the reflection coefficient, represents the argument of the reflection coefficient, Indicates the initial phase of the RF signal, which can be set to 0.

[0068] According to an embodiment of the present invention, based on the modulus of the reflection coefficient and the amplitude of the reflection coefficient, the state information of the quantum chip is obtained. Specifically, the expression of the state information of the quantum chip is as follows:

[0069] (8);

[0070] In the formula, Represents the reflection coefficient of the quantum chip.

[0071] like Figure 2 As shown, the signal analysis module 4 may further include a signal processing unit 402 , wherein an input end of the signal processing unit 402 is connected to a signal output end of the matched filtering module 3 .

[0072] According to an embodiment of the present invention, the signal processing unit 402 can be used to convert the spectrum signal corresponding to the output signal into a time domain signal based on an inverse Fourier transform to obtain a curve of the waveform of the output signal changing over time. The curve of the waveform of the output signal changing over time can be used to extract the signal characteristics of the output signal such as the amplitude and period, so as to analyze the noise, interference or distortion that may exist in the output signal.

[0073] Figure 3 A schematic diagram showing the output result of matched filtering of a radio frequency reflection signal according to a specific embodiment of the present invention is shown.

[0074] like Figure 3 As shown, Figure 3 The above figure shows the unprocessed output signal, Figure 3 The figure below shows the output signal after matched filtering. Figure 3 In the upper and lower figures of , the horizontal axis represents time and the vertical axis represents the real part of the output signal. Since the output signal is a complex signal, only the real part of the output signal is shown to simplify the representation.

[0075] like Figure 3 As shown in the figure above, the unprocessed output signal, the RF reflection signal, contains a lot of noise and glitches, making the signal look chaotic. Since the signal-to-noise ratio is only -9dB, the impact of noise is very significant, making it difficult to directly identify the state change of the quantum chip from the RF reflection signal.

[0076] like Figure 3As shown in the figure below, the noise in the output signal after matched filtering is effectively suppressed, and the signal becomes clearly discernible. Around 0.05ms, there is a significant difference in the signal, which indicates that the quantum chip changes from one state to another. This change is difficult to observe in the unprocessed RF reflection signal.

[0077] Figure 4 A partial schematic diagram shows an output result of matched filtering of a radio frequency reflection signal according to a specific embodiment of the present invention.

[0078] like Figure 4 As shown, Figure 4 The above figure is a partial schematic diagram of the output signal after matched filtering processing. Figure 4 The figure below shows a partial schematic diagram of an ideal reflection signal without noise. Figure 4 In the upper and lower figures of , the horizontal axis represents time and the vertical axis represents the real part of the signal. Since the output signal is a complex signal, only the real part of the output signal is shown to simplify the representation.

[0079] like Figure 4 As shown in the figure above, the output signal after matched filtering can be seen more clearly. The characteristics of the output signal are obvious, and the state change of the quantum chip is also clearly presented. Compared with the unprocessed signal, the output signal after matched filtering is smoother and the noise is significantly suppressed.

[0080] like Figure 4 As shown in the figure below, the output signal after matched filtering is consistent with the ideal reflected signal in terms of signal characteristics. This proves that the RF reflected signal masked by noise can be effectively restored after matched filtering.

[0081] like Figure 4 As shown in the figure below, when the state of the quantum chip changes from the first state to the second state, the corresponding reflection coefficient changes from Change to The result extracted after matched filtering is Change to Therefore, the results extracted after matched filtering are very consistent with the theoretical values, which proves the effectiveness and accuracy of the present invention.

[0082] Figure 5 The diagram shows the variation of the envelope of the output signal over time when matched filtering is performed on the radio frequency reflection signal according to a specific embodiment of the present invention.

[0083] like Figure 5As shown, the horizontal axis represents time, and the vertical axis represents the amplitude of the output signal, and the maximum amplitude corresponds to the modulus of the extracted reflection coefficient. For comparison, the modulus of the reflection coefficient of the measured sub-chip in two different states is marked with a dotted line in the figure. By comparing the maximum value of the extracted output signal envelope with the theoretical value, it can be seen that the degree of agreement between the two is good, which proves the accuracy and reliability of the present invention.

[0084] Figure 6 A schematic diagram showing the specific structure of a device for measuring the state of a quantum chip according to another embodiment of the present invention is shown.

[0085] like Figure 6 As shown, a device for measuring the state of a quantum chip according to another embodiment of the present invention comprises a signal generating unit 101 and an attenuation unit 102, wherein the output end of the signal generating unit 101 is connected to the input end of the attenuator unit 102, and the output end of the attenuator unit 102 is connected to the signal input end of the quantum chip inside the dilution refrigerator.

[0086] like Figure 6 As shown, the signal processing module 2 may include an analog-to-digital conversion unit 201 , the input end of the analog-to-digital conversion unit 201 is connected to the signal output end of the quantum chip inside the dilution refrigerator, and the output end of the analog-to-digital conversion unit 201 is connected to the input end of the matched filter module 3 .

[0087] In this embodiment, the matched filter module 3 is further configured to determine a unit impulse response function based on the information carried by the radio frequency reflection signal and the delay time of the radio frequency reflection signal. The expression of the unit impulse response function is as follows:

[0088] (9);

[0089] In the formula, represents the unit impulse response function, represents the time domain signal corresponding to the RF signal, and t0 represents the delay time of the RF reflection signal.

[0090] According to an embodiment of the present invention, a unit impulse response function is used to perform convolution processing on the radio frequency reflection signal to obtain an output signal. The time domain signal expression corresponding to the output signal is as follows:

[0091] (10);

[0092] In the formula, represents the time domain signal corresponding to the output signal, Represents a convolution operation.

[0093] In this embodiment, the signal analysis module 4 further includes a spectrum analysis unit 401 and a signal processing unit 402, wherein the signal processing unit 402 performs a fast Fourier transform on the output signal to obtain a spectrum signal corresponding to the output signal. Based on the spectrum analysis unit 401, the spectrum signal corresponding to the output signal Perform spectrum analysis to obtain the spectrum information of the output signal, and then obtain the state information of the quantum chip based on the above formulas (6) to (8).

[0094] Based on this, through the above-mentioned time domain implementation, the quantum chip state measurement device provided by the present invention can also effectively measure the reflection coefficient of the quantum chip. Compared with the frequency domain implementation, the time domain implementation has a more intuitive signal processing flow and can effectively filter out link noise through matched filter design. In addition, the time domain implementation can also provide direct observation and analysis capabilities of the signal time domain characteristics, which helps to deeply understand the dynamic behavior of the chip state.

[0095] Figure 7 A flow chart of a method for measuring the state of a quantum chip according to an embodiment of the present invention is shown.

[0096] like Figure 7 As shown, the radio frequency reflection measurement method includes operations S710 to S750.

[0097] In operation S710 , in response to a measurement request for a quantum chip, a radio frequency signal is acquired.

[0098] In operation S720, a radio frequency signal is emitted to a quantum chip inside the dilution refrigerator.

[0099] In operation S730, a signal transformation is performed on the radio frequency reflection signal formed by reflection of the quantum chip to obtain a frequency spectrum of the radio frequency reflection signal.

[0100] In operation S740, the spectrum of the radio frequency reflection signal is filtered using the matched filter coefficient to obtain a spectrum corresponding to the output signal.

[0101] In operation S750, spectrum analysis is performed on the spectrum corresponding to the output signal to obtain state information of the quantum chip.

[0102] It should be noted that the measurement method of the quantum chip state in the embodiment of the present invention corresponds to the measurement device of the quantum chip state in the embodiment of the present invention. The description of the measurement method of the quantum chip state specifically refers to the measurement device of the quantum chip state, which will not be repeated here.

[0103] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box may also occur in an order different from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions. It can be understood by those skilled in the art that the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways, even if such a combination or combination is not explicitly recorded in the present invention. In particular, without departing from the spirit and teachings of the present invention, the features recorded in the various embodiments of the present invention can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present invention.

[0104] The embodiments of the present invention are described above. However, these embodiments are only for the purpose of illustration, and are not intended to limit the scope of the present invention. Although each embodiment is described above, it does not mean that the measures in each embodiment cannot be used in combination advantageously. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A device for measuring the state of a quantum chip, characterized in that: The measuring device comprises: A signal output module, the signal output module is used to output a radio frequency signal to a quantum chip inside the dilution refrigerator, wherein the radio frequency signal is determined based on the signal amplitude, the initial phase and the resonant frequency of the quantum chip; A signal processing module, the signal processing module is used to perform signal conversion on the radio frequency reflection signal formed by the reflection of the quantum chip to obtain the spectrum of the radio frequency reflection signal, wherein the information carried by the radio frequency reflection signal includes the reflection coefficient, link gain and link noise of the quantum chip; A matched filtering module, the matched filtering module is used to filter the spectrum of the radio frequency reflection signal using a matched filtering coefficient to obtain a spectrum corresponding to an output signal; A signal analysis module, the signal analysis module is used to perform spectrum analysis on the spectrum corresponding to the output signal to obtain state information of the quantum chip; Wherein, the matched filtering module is configured as follows: Determining the matched filter coefficient based on the spectrum information and the phase delay coefficient of the radio frequency signal, wherein the phase delay coefficient is determined based on the resonant frequency and the filter frequency of the quantum chip; Based on the matched filter coefficient and the spectrum of the radio frequency reflection signal, obtaining the spectrum corresponding to the output signal; The matched filter coefficient is calculated as follows: ； in, represents the matched filter coefficient; A conjugate signal representing a spectrum signal corresponding to the radio frequency signal; represents the phase delay coefficient, where represents the time constant, , n is a positive integer, represents the resonant frequency of the quantum chip; and f represents the filtering frequency.

2. The measuring device according to claim 1, characterized in that The signal analysis module is configured as follows: Performing spectrum analysis on the spectrum corresponding to the output signal to obtain spectrum information of the output signal; Extracting the amplitude of the output signal and the phase of the output signal from the frequency spectrum information of the output signal; Based on the amplitude of the radio frequency signal, the link gain and the amplitude of the output signal, a modulus value of the reflection coefficient is calculated, wherein the modulus value of the reflection coefficient is used to represent the amplitude attenuation value of the output signal; Based on the initial phase of the radio frequency signal and the phase of the output signal, the amplitude angle of the reflection coefficient is calculated, wherein the amplitude angle of the reflection coefficient is used to represent the phase change value of the output signal; Based on the modulus of the reflection coefficient and the argument of the reflection coefficient, the state information of the quantum chip is obtained.

3. The measuring device according to claim 1, characterized in that The signal output module includes a signal generating unit and an attenuator unit. The signal generating unit is configured to generate an initial radio frequency signal, and the attenuator unit is used to adjust the amplitude of the initial radio frequency signal to obtain the radio frequency signal.

4. The measuring device according to claim 3, characterized in that The measuring device further comprises a control transformation module, wherein the control transformation module is configured to be connected to the signal output module; The control transformation module is used to control the signal amplitude, frequency and initial phase of the initial radio frequency signal.

5. The measuring device according to claim 4, characterized in that The control transformation module is further configured to be connected to the matched filtering module; The control transformation module is also used to determine the matched filter coefficient based on the spectrum information of the radio frequency signal and the phase delay coefficient, and configure the matched filter coefficient in the matched filter module.

6. The measuring device according to claim 1, characterized in that The signal processing module includes an analog-to-digital conversion unit and a signal conversion unit. The analog-to-digital conversion unit is configured to collect and perform analog-to-digital conversion on the radio frequency reflection signal in response to receiving the radio frequency reflection signal, so as to obtain a digital signal of the radio frequency reflection signal; The signal conversion unit is configured to perform Fourier transform processing on the digital signal of the radio frequency reflection signal to obtain the frequency spectrum of the radio frequency reflection signal.

7. The measuring device according to claim 1, characterized in that The matched filtering module is further configured to: Determining a unit impulse response function based on the delay time of the radio frequency signal and the radio frequency reflected signal; The unit impulse response function is used to perform convolution processing on the radio frequency reflection signal to obtain the output signal.

8. The measuring device according to claim 7, characterized in that The signal analysis module is further configured to: Performing Fourier transform on the output signal to obtain the frequency spectrum corresponding to the output signal; Performing spectrum analysis on the spectrum corresponding to the output signal to obtain state information of the quantum chip; The control transformation module is also configured to: The unit impulse response function is determined based on the time domain signal of the radio frequency signal and the delay time of the radio frequency reflection signal, and the unit impulse response function is configured in the matched filtering module.

9. A method for measuring the state of a quantum chip, applied to the device for measuring the state of a quantum chip as claimed in any one of claims 1 to 8, characterized in that: The measuring method comprises: In response to a measurement request for the quantum chip, acquiring a radio frequency signal; Emittering the radio frequency signal to a quantum chip inside a dilution refrigerator, wherein the radio frequency signal is determined based on a signal amplitude, an initial phase, and a resonant frequency of the quantum chip; Performing signal transformation on a radio frequency reflection signal formed by reflection of the quantum chip to obtain a spectrum of the radio frequency reflection signal, wherein the information carried by the radio frequency reflection signal includes a reflection coefficient, a link gain, and a link noise of the quantum chip; Using a matched filter coefficient to filter the spectrum of the radio frequency reflection signal to obtain a spectrum corresponding to the output signal; performing spectrum analysis on the spectrum corresponding to the output signal to obtain state information of the quantum chip; The filtering of the spectrum of the radio frequency reflection signal by using the matched filter coefficient to obtain a spectrum corresponding to the output signal includes: Determining the matched filter coefficient based on the spectrum information and the phase delay coefficient of the radio frequency signal, wherein the phase delay coefficient is determined based on the resonant frequency and the filter frequency of the quantum chip; Based on the matched filter coefficient and the spectrum of the radio frequency reflection signal, obtaining the spectrum corresponding to the output signal; The matched filter coefficient is calculated as follows: ； in, represents the matched filter coefficient; A conjugate signal representing a spectrum signal corresponding to the radio frequency signal; represents the phase delay coefficient, where represents the time constant, , n is a positive integer, represents the resonant frequency of the quantum chip; and f represents the filtering frequency.

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