Device, system and method for measuring radio frequency reflection of quantum chip

Abstract

The present invention provides a device, system and method for measuring radio frequency reflection of a quantum chip, which mainly relates to the field of quantum computing technology. The radio frequency reflection measuring device includes: a signal source, a power divider, a delay line unit, an amplitude and phase controller, a mixer, and a signal processing unit; the signal source is used to generate a frequency modulated continuous wave signal; the power divider is used to divide the frequency modulated continuous wave signal into a local oscillator branch signal and a radio frequency branch signal; the amplitude and phase controller is used to adjust the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; the delay line unit is used to adjust the delay time of the radio frequency branch signal to obtain a radio frequency signal; the mixer is used to mix the local oscillator signal and the radio frequency reflection signal formed by the reflection of the quantum chip to obtain a mixed signal; the signal processing unit is used to perform spectrum analysis and signal transformation on the mixed signal to obtain measurement 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 radio frequency reflection measurement device, system and method for 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 technology uses point-frequency continuous waves to irradiate quantum chip samples. However, since most traditional measurement methods synchronously demodulate the mixed signal to the baseband, the measurement process is easily affected by noise and interference in the signal link and its environment, resulting in a decrease in the accuracy of the measurement results. In addition, when the number of bits is expanded, the traditional synchronous demodulation method cannot distinguish which quantum bit the signal comes from. Summary of the invention

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

[0005] One aspect of the present invention provides a radio frequency reflection measurement device for a quantum chip, the radio frequency reflection measurement device comprising: a signal source, a power divider, a delay line unit, an amplitude and phase controller, a mixer, and a signal processing unit; the signal source is used to generate a frequency modulated continuous wave signal; the power divider is used to divide the frequency modulated continuous wave signal into a local oscillator branch signal and a radio frequency branch signal; the amplitude and phase controller is used to adjust the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; the delay line unit is used to adjust the delay time of the radio frequency branch signal to obtain a radio frequency signal, wherein the radio frequency signal is incident on a quantum chip inside a dilution refrigerator; the mixer is used to mix the local oscillator signal with a radio frequency reflection signal formed by reflection of the quantum chip to obtain a mixed signal; the signal processing unit is used to perform spectrum analysis and signal conversion on the mixed signal to obtain measurement information of the quantum chip.

[0006] According to an embodiment of the present invention, the signal processing unit is configured to: perform spectrum analysis on the mixing signal based on the frequency modulation slope of the signal source and the delay time of the RF branch signal to determine the signal frequency of the mixing signal; determine the amplitude and phase corresponding to the signal frequency of the mixing signal based on the signal frequency of the mixing signal; determine the measurement information of the quantum chip based on the amplitude and phase corresponding to the signal frequency of the mixing signal.

[0007] According to an embodiment of the present invention, based on the amplitude and phase corresponding to the signal frequency of the mixing signal, determining the measurement information of the quantum chip includes: calculating the amplitude information of the reflection coefficient based on the amplitude corresponding to the signal frequency of the mixing signal, the amplitude of the RF branch signal and the amplitude of the local oscillator branch signal; and calculating the phase information of the reflection coefficient based on the phase corresponding to the signal frequency of the mixing signal and the additional phase.

[0008] According to an embodiment of the present invention, the frequency adjustment range of the above-mentioned frequency modulated continuous wave signal is determined based on the resonance frequency of the quantum bits included in the above-mentioned quantum chip.

[0009] According to an embodiment of the present invention, the RF reflection measurement device further includes an attenuator unit, wherein the attenuator unit is configured to be connected to the output end of the delay line unit, and the attenuator unit is used to adjust the signal amplitude of the RF signal.

[0010] According to an embodiment of the present invention, the above-mentioned RF reflection measurement device also includes a filtering unit, wherein the above-mentioned filtering unit is configured to be connected to the output end of the above-mentioned power divider, and the above-mentioned filtering unit is used to filter the above-mentioned RF branch signal based on the center frequency to obtain a filtered RF branch signal, wherein the above-mentioned center frequency is configured to match the resonant frequency of the quantum bits contained in the above-mentioned quantum chip.

[0011] According to an embodiment of the present invention, the power divider is further configured to divide the frequency modulated continuous wave signal into the local oscillator branch signal and multiple radio frequency branch sub-signals; the filtering unit includes multiple filters, and the multiple filters are used to filter the multiple radio frequency branch sub-signals based on their respective center frequencies to obtain multiple radio frequency branch sub-signals after filtering, wherein the center frequencies of the multiple filters are respectively configured to match the resonant frequencies of the multiple quantum bits; the delay line unit includes multiple delay lines, and the multiple delay lines are used to adjust the delay time of the multiple radio frequency branch sub-signals after filtering to obtain multiple radio frequency sub-signals; wherein the multiple radio frequency sub-signals are respectively incident on the quantum chip inside the dilution refrigerator, and are reflected by the multiple quantum bits included in the quantum chip to obtain multiple radio frequency reflection sub-signals; wherein the radio frequency reflection measurement device also includes a power synthesizer, and the power synthesizer is configured to synthesize the multiple radio frequency reflection sub-signals to obtain the radio frequency reflection signal.

[0012] Another aspect of the present invention provides a radio frequency reflection measurement system for a quantum chip, the radio frequency reflection measurement system comprising multiple signal sources, multiple radio frequency branch signal processing modules, an amplitude and phase controller, a mixer, and a signal processing unit, wherein each of the radio frequency branch signal processing modules comprises a power divider and a delay line unit; the multiple signal sources are configured to synchronously generate frequency modulated continuous wave signals; the power divider is used to divide the frequency modulated continuous wave signal into multiple radio frequency branch signals; the delay line unit is used to adjust the delay time and amplitude of the multiple radio frequency branch signals to obtain radio frequency signals, wherein the multiple radio frequency signals are incident on the quantum chip inside the dilution refrigerator; the amplitude and phase controller is used to adjust the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; the mixer is used to mix the local oscillator signal with the radio frequency reflection signal formed by reflection of the quantum chip to obtain a mixed signal; the signal processing unit is used to perform spectrum analysis and signal conversion on the mixed signal to obtain measurement information of the quantum chip.

[0013] According to an embodiment of the present invention, the above-mentioned RF reflection measurement system also includes multiple delay modules, wherein each of the above-mentioned delay modules is used to control the transmission time of the above-mentioned frequency-modulated continuous wave signal from the above-mentioned signal source to the above-mentioned power divider, so as to ensure that the power dividers included in the above-mentioned multiple RF branch signal processing modules are in the same phase state when receiving the above-mentioned frequency-modulated continuous wave signal; the above-mentioned RF reflection measurement system also includes multiple power synthesizers, wherein the above-mentioned multiple power synthesizers are configured to synthesize and process multiple RF reflection signals to obtain the above-mentioned RF reflection signals.

[0014] Another aspect of the present invention provides a method for measuring radio frequency reflection of a quantum chip, which is applied to a radio frequency reflection measurement device as described in any one of the above items or a radio frequency reflection measurement system as described in any one of the above items, and the radio frequency reflection measurement method includes: in response to a radio frequency reflection measurement request for the quantum chip, obtaining a frequency modulated continuous wave signal generated by a signal source; dividing the frequency modulated continuous wave signal into a local oscillator branch signal and a radio frequency branch signal; adjusting the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; adjusting the delay time of the radio frequency branch signal to obtain a radio frequency signal, wherein the radio frequency signal is incident on the quantum chip inside a dilution refrigerator; mixing the local oscillator signal and the radio frequency reflection signal formed by reflection of the quantum chip to obtain a mixed signal; performing spectrum analysis and signal transformation on the mixed signal to obtain measurement information of the quantum chip.

[0015] According to an embodiment of the present invention, the signal to be measured is down-converted to an intermediate frequency by a frequency modulated continuous wave signal and an adjustable frequency modulation slope. By demodulating the signal to be measured to an intermediate frequency region far away from the baseband, noise and interference near the baseband can be effectively avoided. Since the frequency of the intermediate frequency signal is far away from the baseband, the environmental noise and electromagnetic interference it is subject to are relatively small, thereby improving the signal's anti-interference ability and signal-to-noise ratio. In addition, an adjustable delay time is generated in the radio frequency branch through a delay line unit, so that the radio frequency reflection signals of different quantum bits can be distinguished in the frequency domain, and independent measurement and rapid addressing of quantum bits can be achieved. 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 radio frequency reflection measurement device for a quantum chip according to an embodiment of the present invention is shown.

[0018] Figure 2 A schematic diagram of a radio frequency reflection measurement device for a quantum chip according to a specific embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram of an output signal waveform of a radio frequency reflection measurement device of a quantum chip according to a specific embodiment of the present invention is shown.

[0020] Figure 4 A schematic diagram of spectrum analysis of a radio frequency reflection measurement device of a quantum chip according to a specific embodiment of the present invention is shown.

[0021] Figure 5 A schematic diagram of a signal waveform generated by a signal source according to a specific embodiment of the present invention is shown.

[0022] Figure 6 A schematic diagram of the spectrum of demodulating a radio frequency reflection signal to an intermediate frequency according to a specific embodiment of the present invention and demodulating a radio frequency reflection signal to a baseband using a traditional method is shown.

[0023] Figure 7 A schematic diagram of a radio frequency reflection measurement device for a quantum chip according to another specific embodiment of the present invention is shown.

[0024] Figure 8 A schematic diagram of a radio frequency reflection measurement device for a quantum chip according to another embodiment of the present invention is shown.

[0025] Fig. 9 A schematic diagram of a radio frequency reflection measurement system for a quantum chip according to an embodiment of the present invention is shown.

[0026] Fig.10A schematic diagram of a radio frequency branch signal processing module according to an embodiment of the present invention is shown.

[0027] Fig.11 A flow chart of a method for measuring radio frequency reflection of a quantum chip according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.).

[0032] 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.

[0033] Traditional RF reflection measurement technology uses a point-frequency continuous wave (carrier) to irradiate the quantum chip sample, and then uses a local oscillator signal with the same frequency as the RF signal to mix and demodulate it to zero intermediate frequency. From the demodulated signal, the amplitude and phase of the reflection coefficient of the chip under test can be extracted, and then the state information of the bit (quantum dot) can be obtained.

[0034] However, since most traditional measurement methods demodulate the mixed signal to baseband, RF reflection measurement technology is easily affected by noise and interference in the signal link and its environment, which may lead to a decrease in the accuracy of the measurement results. In addition, when the number of bits is extended, the traditional synchronous demodulation method cannot distinguish which bit the signal comes from, that is, there is an addressing problem.

[0035] In order to circumvent the addressing problem, the existing technology proposes to use heterodyne demodulation, but this method requires a transmission signal source, a local oscillator source and a mixer for each bit, which greatly increases the system complexity and resource consumption. When the number of bits is expanded on a large scale, this method will not be able to meet the expansion needs.

[0036] The above problems all make it necessary to explore other test devices and methods that can simplify system design, save resources, and are easy to expand on a large scale. At present, there is no relevant research in the field of quantum computing. In the process of realizing the present invention, it is found that a signal form used in the fields of communication, radar, etc. - frequency modulated continuous wave can quickly generate a frequency-adjustable signal, and the frequency difference between the signal emitted by the transmitting source and the target echo signal can be used to measure the distance between the two. Based on this, considering that the resonant frequencies of different bits are different, their positions are also different. If they can be distinguished by their positions, addressing can also be achieved. Further, through simulation analysis, it is found that this method can realize the positional distinction between different bits on the quantum chip, but because the distance difference between bits is too small (therefore the delay difference is also small), the required computing resources are extremely large, so that it is almost impossible to implement it in engineering at present. Furthermore, if it is noted that it is only necessary to distinguish between different bits without paying attention to their actual geometric positions, the hardware and computing resources can be greatly reduced by artificially adjusting the delay difference between bits, and the addressing of bits can be achieved.

[0037] In view of this, the embodiment of the present invention down-converts the signal to be measured to an intermediate frequency by using a frequency modulated continuous wave signal and an adjustable frequency modulation slope. By demodulating the signal to be measured to an intermediate frequency region far away from the baseband, noise and interference near the baseband can be effectively avoided. Since the frequency of the intermediate frequency signal is far away from the baseband, the environmental noise and electromagnetic interference it is subject to are relatively small, thereby improving the signal's anti-interference ability and signal-to-noise ratio. In addition, an adjustable delay time is generated in the radio frequency branch through a delay line unit, so that the radio frequency reflection signals of different quantum bits can be distinguished in the frequency domain, and independent measurement and rapid addressing of quantum bits can be achieved.

[0038] Specifically, an embodiment of the present invention provides a radio frequency reflection measurement device for a quantum chip, comprising: a signal source, a power divider, a delay line unit, an amplitude and phase controller, a mixer, and a signal processing unit; the signal source is used to generate a frequency modulated continuous wave signal; the power divider is used to divide the frequency modulated continuous wave signal into a local oscillator branch signal and a radio frequency branch signal; the amplitude and phase controller is used to adjust the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; the delay line unit is used to adjust the delay time of the radio frequency branch signal to obtain a radio frequency signal; the mixer is used to mix the local oscillator signal and the radio frequency reflection signal formed by reflection of the quantum chip to obtain a mixed signal; the signal processing unit is used to perform spectrum analysis and signal transformation on the mixed signal to obtain measurement information of the quantum chip.

[0039] Figure 1 A schematic diagram of a radio frequency reflection measurement device for a quantum chip according to an embodiment of the present invention is shown.

[0040] like Figure 1 As shown, the radio frequency reflection measurement device includes a signal source 1, a power divider 2, a delay line unit 3, an amplitude and phase controller 4, a mixer 5 and a signal processing unit 6.

[0041] The radio frequency reflection measurement device is in a room temperature environment, and the measured sub-chip is in a low temperature environment of a dilution refrigerator.

[0042] According to an embodiment of the present invention, the output end of the signal source 1 can be connected to the input end of the power divider 2. The signal source 1 is used to generate a frequency modulated continuous wave signal, and the frequency modulation slope of the signal source 1 is adjustable. The frequency modulation slope is used to characterize the rate at which the frequency of the frequency modulated continuous wave signal changes over time. In addition, the frequency modulation range of the signal source 1 can cover the resonant frequency of the measured sub-chip, for example, the signal source 1 can generate a signal that matches or is close to the resonant frequency of the measured sub-chip.

[0043] According to an embodiment of the present invention, the RF output end of the power divider 2 can be connected to the input end of the delay line unit 3, and the local oscillator output end of the power divider 2 can be connected to the input end of the amplitude and phase controller 4. The power divider 2 is used to divide the received frequency modulated continuous wave signal into a local oscillator branch signal and a radio frequency branch signal, wherein the local oscillator branch signal is input to the amplitude and phase controller 4, and the radio frequency branch signal is input to the delay line unit 3. Among them, the radio frequency branch signal may include multiple branch signals.

[0044] According to an embodiment of the present invention, the delay line unit 3 is used to generate an adjustable delay time in the RF branch, so that the delay line unit 3 introduces a delay difference during the RF branch signal transmission process, thereby distinguishing the RF reflection signals of different quantum bits in the frequency domain.

[0045] According to an embodiment of the present invention, the output end of the delay line unit 3 can be connected to the RF input port of the dilution refrigerator. The time delay of the RF branch signal is adjusted by the delay line unit 3 to obtain a RF signal, which can be incident on the measured sub-chip inside the dilution refrigerator, and after being reflected by the measured sub-chip, a RF reflection signal carrying the information of the measured sub-chip is formed.

[0046] According to the embodiment of the present invention, the output end of the amplitude and phase controller 4 is connected to the local oscillator signal input end of the mixer 5. The amplitude and phase controller 4 is used to accurately adjust the phase and amplitude of the local oscillator branch signal. After the local oscillator branch signal is adjusted by the amplitude and phase controller 4, a local oscillator signal that is coherent with the radio frequency branch signal is obtained.

[0047] According to the embodiment of the present invention, the phase error between the local oscillator branch signal and the radio frequency branch signal caused by factors such as signal transmission path differences and device delays can be eliminated through phase adjustment of the amplitude and phase controller 4. Through the amplitude adjustment of the amplitude and phase controller 4, it can be ensured that the local oscillator signal and the radio frequency branch signal are matched in intensity, so as to ensure that the local oscillator signal obtained after adjustment is coherent with the radio frequency branch signal, and achieve precision alignment in time.

[0048] According to an embodiment of the present invention, the RF signal input end of the mixer 5 can be connected to the RF output port of the dilution refrigerator, and the output end of the mixer 5 can be connected to the input end of the signal processing unit 6. The mixer 5 is used to mix the local oscillator signal and the RF reflection signal formed by the reflection of the quantum chip to obtain a mixed signal. Among them, the mixed signal obtained by the mixer 5 can be configured as an intermediate frequency signal, and the signal frequency of the intermediate frequency signal is configured to be lower than the carrier frequency and higher than the baseband frequency.

[0049] According to an embodiment of the present invention, the signal processing unit 6 is used to perform spectrum analysis and model conversion on the mixed signal to obtain measurement information of the quantum chip. The measurement information of the quantum chip includes the reflection coefficient of the measured sub-chip, and the reflection coefficient of the measured sub-chip includes amplitude information and phase information.

[0050] Based on this, the embodiments of the present invention down-convert the measured signal to an intermediate frequency through a frequency modulated continuous wave signal and an adjustable frequency modulation slope. By demodulating the measured signal to an intermediate frequency region far away from the baseband, the noise and interference near the baseband can be effectively avoided. Since the frequency of the intermediate frequency signal is far away from the baseband, the environmental noise and electromagnetic interference it is subject to are relatively small, thereby improving the signal's anti-interference ability and signal-to-noise ratio. In addition, an adjustable delay time is generated in the radio frequency branch through a delay line unit, so that the radio frequency reflection signals of different quantum bits can be distinguished in the frequency domain, and independent measurement and rapid addressing of quantum bits can be achieved. In addition, when the number of quantum bits is small, the radio frequency reflection measurement device provided by the present application only needs a signal source, a local oscillator source and a mixer to complete the measurement of the quantum chip. This design can save resources and simplify system design.

[0051] Figure 2 A schematic diagram of a radio frequency reflection measurement device for a quantum chip according to a specific embodiment of the present invention is shown.

[0052] like Figure 2 As shown, the RF reflection measurement device also includes an attenuator unit 7. The input end of the attenuator unit 7 can be connected to the output end of the delay line unit 3, and the output end of the attenuator unit 7 can be connected to the RF input port of the dilution refrigerator. During the RF reflection measurement process, the amplitude of the RF signal may change due to factors such as transmission loss and component characteristics. In order to ensure the accuracy and stability of the signal amplitude, the attenuator unit 7 is used to adjust and control the amplitude of the RF signal incident on the measured sub-chip.

[0053] According to a specific embodiment of the present invention, Figure 2 The measurement method of the radio frequency reflection measurement device in this embodiment is described.

[0054] The signal source 1 generates a frequency modulated continuous wave signal. The power divider 2 divides the frequency modulated continuous wave signal generated by the signal source 1 into a local oscillator branch signal and a radio frequency branch signal. The amplitude and phase controller 4 can adjust the amplitude and phase of the local oscillator branch signal. The expression of the local oscillator signal obtained after adjustment is as follows:

[0055] (1);

[0056] Where, LO represents the local oscillator signal; Indicates the starting frequency of the FM continuous wave signal; represents the frequency modulation slope of the FM continuous wave signal; a represents the amplitude of the local oscillator signal, where the starting frequency of the FM continuous wave signal are known parameters, where the frequency modulation slope of the frequency modulated continuous wave signal is The local oscillator signal amplitude a can be obtained based on the power of the frequency modulated continuous wave signal, the loss of the power divider 2 and the attenuation of the amplitude and phase controller 4. Therefore, the local oscillator signal amplitude a is a known parameter.

[0057] In this specific embodiment, the delay line unit 3 adjusts the delay time of the RF branch signal, and adjusts the amplitude of the RF branch signal through the attenuator unit 7 to obtain a RF signal, which is incident on the measured sub-chip in the dilution refrigerator through the attenuator unit 7, and is reflected by the measured sub-chip to obtain a RF reflection signal carrying the quantum chip state information. The expression of the RF reflection signal is as follows:

[0058] (2);

[0059] In the formula, represents the RF reflection signal, A represents the RF reflection signal amplitude, represents the reflection coefficient of the measured sub-chip, Indicates the delay difference between the local oscillator branch signal and the RF branch signal. Among them, the reflection coefficient of the measured sub-chip It can be used to characterize the state of the measured sub-chip; the RF reflection signal amplitude A can be obtained based on the power of the FMCW signal and the loss of the power divider 2, so the RF reflection signal amplitude A is a known parameter. Among them, the delay difference between the local oscillator branch signal and the RF branch signal is The delay time of the delay line can be adjusted through program control.

[0060] In this specific embodiment, when the mixer 5 receives the local oscillator signal and the radio frequency reflection signal, it mixes the local oscillator signal and the radio frequency reflection signal to obtain a mixed signal, wherein the expression of the mixed signal is as follows:

[0061] (3);

[0062] In the formula, Represents a mixed signal.

[0063] In this specific embodiment, the signal processing unit 6 may include a low-pass filter and a signal processing subunit. The low-pass filter can be used to filter out the high-frequency components in the mixed signal, and the intermediate frequency signal is obtained after filtering. The signal processing subunit then collects and performs spectrum analysis on the intermediate frequency signal to extract information such as the frequency, amplitude, and phase of the intermediate frequency signal. Specifically, the intermediate frequency signal obtained after the mixed signal is filtered out by low-pass filtering and the high-frequency components are expressed as follows:

[0064] (4);

[0065] In the formula, represents the intermediate frequency signal, Represents the reflection coefficient of the measured sub-chip.

[0066] In this specific embodiment, the signal processing unit 6 performs spectrum analysis (including Fourier transform) on the intermediate frequency signal, and extracts the signal frequency of the intermediate frequency signal based on the frequency modulation slope of the signal source 1 and the delay time of the RF branch signal, and determines the amplitude and phase corresponding to the signal frequency of the intermediate frequency signal based on the signal frequency of the intermediate frequency signal and the spectrum information of the intermediate frequency signal. Specifically, the signal frequency expression of the intermediate frequency signal is as follows:

[0067] (5);

[0068] In the formula, Indicates the signal frequency of the IF signal.

[0069] In this specific embodiment, in order to obtain the reflection coefficient of the measured sub-chip itself, the RF branch signal amplitude, the local oscillator signal amplitude and the additional phase in the intermediate frequency signal can be eliminated to obtain the amplitude information and phase information of the reflection coefficient.

[0070] For example, the IF signal can be The amplitude at is divided by half of the product of the known RF branch signal amplitude and the local oscillator signal amplitude to eliminate the influence of these two amplitudes and obtain the amplitude information of the reflection coefficient. The amplitude information expression of the reflection coefficient is as follows:

[0071] (6);

[0072] In the formula, Represents the amplitude information of the reflection coefficient, Indicates that the intermediate frequency signal is The range of the place.

[0073] For example, the intermediate frequency signal can also be The phase at the position minus the additional phase is used to eliminate the influence of the additional phase introduced by the low-pass filter in the link, and the phase information of the reflection coefficient is obtained. The phase information expression of the reflection coefficient is as follows:

[0074] (7);

[0075] In the formula, Represents the phase information of the reflection coefficient, Indicates that the intermediate frequency signal is The phase at Indicates additional phase.

[0076] In this specific embodiment, based on the amplitude information and phase information of the reflection coefficient corresponding to the measured sub-chip, the measurement information of the measured sub-chip is obtained. The expression of the measurement information of the measured sub-chip is as follows:

[0077] (8);

[0078] In the formula, Represents the reflection coefficient of the measured sub-chip.

[0079] Figure 3 A schematic diagram of an output signal waveform of a radio frequency reflection measurement device of a quantum chip according to a specific embodiment of the present invention is shown.

[0080] like Figure 3 As shown, the horizontal axis represents time t, and the vertical axis represents the intermediate frequency signal amplitude. Since the intermediate frequency signal is a complex signal, only the real part is used in this figure.

[0081] In this waveform diagram, the unmarked solid line represents the measured intermediate frequency signal, and the star-shaped solid line represents the ideal noise-free intermediate frequency signal. Figure 3 As shown, the signal-to-noise ratio Under the condition of , there is a small difference in amplitude between the measured intermediate frequency signal and the ideal noise-free intermediate frequency signal, but the frequency, phase, etc. are basically consistent.

[0082] Figure 4 A schematic diagram of spectrum analysis of a radio frequency reflection measurement device of a quantum chip according to a specific embodiment of the present invention is shown.

[0083] like Figure 4 As shown, the horizontal axis represents the frequency f, and the vertical axis represents the signal strength corresponding to the frequency. , the ideal noise-free intermediate frequency signal frequency is , ideal reflection coefficient Under the conditions, from Figure 4 It can be obtained that the measured intermediate frequency signal frequency is also 0.5MHz, and the amplitude is , the phase is The results are consistent with the ideal values, and the amplitude and phase errors of the reflection coefficient are and .

[0084] Figure 5 A schematic diagram of a signal waveform generated by a signal source according to a specific embodiment of the present invention is shown.

[0085] like Figure 5As shown in FIG. 1 , for the signal source used in the embodiment of the present invention, the horizontal axis of the signal waveform diagram generated by the signal source represents the time of the adjustable continuous wave signal emission, and the vertical axis represents the frequency of the adjustable continuous wave signal. Figure 5 It can be seen that the frequency of the adjustable continuous wave signal increases linearly with time, which means that the frequency change of the adjustable continuous wave signal is uniform, without sudden jumps or irregular changes, and when the frequency of the signal reaches a certain maximum value After that, it will start to decrease (or return to the initial frequency ), and starts to increase linearly again, thus showing a periodic change. In a specific embodiment of the present invention, this linearly changing frequency range is configured to cover the resonant frequencies of multiple quantum bits, which means that the signal can interact with these quantum bits one by one or simultaneously.

[0086] Figure 6 A schematic diagram of the spectrum of demodulating a radio frequency reflection signal to an intermediate frequency according to a specific embodiment of the present invention and demodulating a radio frequency reflection signal to a baseband using a traditional method is shown.

[0087] like Figure 6 As shown, the horizontal axis represents the frequency f, and the vertical axis represents the signal strength corresponding to the frequency. Figure 6 As shown by the upper arrow in the figure, the traditional method down-converts the RF signals of different frequency bands to zero intermediate frequency, and the frequencies overlap. In order to address the overlapping signals, different demodulation links need to be used. Therefore, the traditional method consumes a lot of resources and the system is relatively complex.

[0088] like Figure 6 As shown by the lower arrow in , the present invention can down-convert radio frequency signals of different frequency bands to different intermediate frequencies, with a large frequency distinction, and can be used for addressing multiple quantum bits. Since the signal frequency of the intermediate frequency signal can be flexibly adjusted by the frequency modulation slope of the signal source and the delay difference of the delay line unit, for different measured sub-chips, it is only necessary to adjust the frequency modulation slope and frequency modulation time of the signal source to generate the required frequency without replacing the signal source, local oscillator signal and mixer. In addition, since the intermediate frequency signal is demodulated to an intermediate frequency far away from the baseband frequency, the anti-noise ability of the device can be improved, and the frequency overlap between different channels can be reduced by accurately adjusting the signal frequency of the intermediate frequency signal.

[0089] Figure 7 A schematic diagram of a radio frequency reflection measurement device for a quantum chip according to another specific embodiment of the present invention is shown.

[0090] like Figure 7As shown, the RF reflection measurement device also includes a filtering unit 8. The input end of the filtering unit 8 can be connected to the RF output end of the power divider 2. The filtering unit 8 can filter the RF branch signal based on its center frequency to accurately extract a signal component that matches the resonant frequency of at least one quantum bit in the measured sub-chip from the complex RF branch signal.

[0091] Among them, the center frequency of the filtering unit 8 can be configured to match the resonant frequency of at least one quantum bit in the measured sub-chip, and only the RF branch signal with a frequency close to the quantum bit resonant frequency can pass through the filtering unit 8 smoothly, while signals of other frequencies will be effectively suppressed.

[0092] Figure 8 A schematic diagram of a radio frequency reflection measurement device for a quantum chip according to another embodiment of the present invention is shown.

[0093] like Figure 8 As shown, when the quantum chip includes n quantum bits, the power divider 2 divides the adjustable continuous wave signal generated by the signal source 1 into measurement channels, of which The measurement channels are used as RF branches, corresponding to the n quantum bits on the measured sub-chip respectively; The measurement channels are used as local oscillator branches.

[0094] In this embodiment, The local oscillator signal is incident on the amplitude and phase controller 4 as the local oscillator branch signal, and the amplitude and phase controller 4 adjusts the amplitude and phase of the local oscillator branch signal to obtain a local oscillator signal that is input to the local oscillator input port of the mixer 5; The branch signal is incident on the filter unit 8 as a radio frequency branch sub-signal.

[0095] like Figure 8 As shown, the filter unit 8 includes n adjustable filters, and the delay line unit 3 includes n delay lines. The RF branches of the circuit are each equipped with an adjustable filter and a delay line.

[0096] Among them, for the adjustable filter on each RF branch, its center frequency can be configured to be a frequency that matches the resonant frequency of the quantum bit corresponding to the RF branch, so as to ensure that the frequency of the RF branch sub-signal incident from the RF branch can only pass through the filter smoothly at a frequency that matches the resonant frequency of the quantum bit corresponding to the RF branch.

[0097] Among them, the delay line on each RF branch is used to adjust the delay time of the filtered RF branch sub-signal, so that the delay time of each measurement channel is different, so that the RF reflection sub-signal reflected by each quantum bit can be distinguished in time.

[0098] like Figure 8 As shown, when the quantum chip includes n quantum bits, the RF reflection measurement device of the quantum chip also includes a power synthesizer 9, which is used to synthesize n RF reflection sub-signals to obtain one RF reflection signal and input it to the mixer 5.

[0099] According to a specific embodiment of the present invention, Figure 8 A measurement method of the radio frequency reflection measurement device according to another embodiment is described.

[0100] The signal source 1 generates a frequency modulated continuous wave signal, wherein the frequency adjustment range of the signal source 1 is configured to include a resonant frequency range of n quantum bits.

[0101] Power divider 2 divides the FM continuous wave signal generated by signal source 1 into measurement channels, of which The measurement channels are used as RF branches, corresponding to the n quantum bits on the measured sub-chip respectively; The amplitude and phase controller 4 can adjust the amplitude and phase of the local oscillator branch signal transmitted by the local oscillator branch. The expression of the local oscillator signal obtained after adjustment is shown in formula (1).

[0102] The RF branch sub-signal passes through the The radio frequency branches are incident on n tunable filters, wherein the center frequencies of the n tunable filters are consistent with the resonant frequencies of the n quantum bits corresponding thereto.

[0103] Each RF branch sub-signal is filtered by an adjustable filter and then transmitted to an adjustable delay line to adjust the delay time of the filtered RF branch sub-signal to obtain a RF sub-signal. The delay difference of n RF branches is recorded as ,in, Among them, the expression of the i-th RF sub-signal is as follows:

[0104] (9);

[0105] In the formula, represents the ith RF sub-signal, A represents the amplitude of the RF reflection signal, represents the delay difference between the local oscillator branch signal and the i-th RF branch sub-signal. The RF reflection signal amplitude A can be obtained based on the power of the FMCW signal and the loss of the power divider 2. Therefore, the RF reflection signal amplitude A is a known parameter. The delay difference between the local oscillator branch signal and the i-th RF branch sub-signal is The delay time of each adjustable delay line can be adjusted through program control.

[0106] The n-channel RF sub-signals are incident on the n qubits included in the quantum chip of the dilution refrigerator respectively, and the n-channel RF reflection sub-signals carrying the quantum chip state information are obtained after being reflected by the n qubits. The n-channel RF reflection sub-signals are emitted to the power synthesizer 9 to synthesize the n-channel RF reflection sub-signals into one RF reflection signal. The expression of the i-th RF reflection sub-signal is as follows:

[0107] (10);

[0108] In the formula, represents the i-th RF reflected sub-signal, represents the reflection coefficient of the i-th quantum bit.

[0109] When the mixer 5 receives the local oscillator signal and the radio frequency reflection signal, it mixes the local oscillator signal and the radio frequency reflection signal to obtain a mixed signal, wherein the expression of the mixed signal is as follows:

[0110] (11);

[0111] In the formula, Represents a mixed signal.

[0112] The signal processing unit 6 may include a low-pass filter and a signal processing subunit. The low-pass filter can be used to filter out the high-frequency components in the mixed signal, and the intermediate frequency signal is obtained after filtering. The signal processing subunit then performs spectrum analysis on the intermediate frequency signal to extract information such as the frequency, amplitude, and phase of the intermediate frequency signal. Specifically, the intermediate frequency signal obtained after the mixed signal is filtered out by low-pass filtering and the high-frequency components are expressed as follows:

[0113] (12);

[0114] In the formula, Represents the intermediate frequency signal.

[0115] The signal processing unit 6 performs spectrum analysis (such as Fourier transform) on the intermediate frequency signal, and extracts the signal frequency of the intermediate frequency signal based on the frequency modulation slope of the signal source 1 and the delay time of the RF branch sub-signal, and determines the amplitude and phase corresponding to the signal frequency of the intermediate frequency signal based on the signal frequency of the intermediate frequency signal and the spectrum information of the intermediate frequency signal. Specifically, the signal frequency expression of the intermediate frequency signal is as follows:

[0116] (13);

[0117] In the formula, Indicates the signal frequency of the IF signal.

[0118] In this specific embodiment, in order to obtain the reflection coefficient of the measured sub-chip itself, the RF branch signal amplitude, the local oscillator signal amplitude and the additional phase in the intermediate frequency signal can be eliminated to obtain the amplitude information and phase information of the reflection coefficient. Based on the amplitude information and phase information of the reflection coefficient corresponding to the measured sub-chip, the measurement information of the measured sub-chip is obtained. Among them, the measurement information expression of the measured sub-chip is as follows:

[0119] (14);

[0120] In the formula, represents the reflection coefficient of the i-th quantum bit, represents the amplitude information of the reflection coefficient of the i-th quantum bit, Represents the phase information of the reflection coefficient of the i-th quantum bit.

[0121] Based on this, since the signal frequency of the intermediate frequency signal can be flexibly adjusted through the frequency modulation slope of the signal source and the delay difference of the delay line unit, for different measured sub-chips, only the frequency modulation slope and frequency modulation time of the signal source need to be adjusted to generate the required frequency without replacing the signal source, local oscillator signal and mixer. The universality is high and the hardware cost and maintenance complexity are reduced. In addition, since the intermediate frequency signal is demodulated to an intermediate frequency far away from the baseband frequency, the anti-noise ability of the device can be improved. By accurately adjusting the signal frequency of the intermediate frequency signal, the device can reduce the frequency overlap between different channels, thereby reducing crosstalk.

[0122] Fig. 9 A schematic diagram of a radio frequency reflection measurement system for a quantum chip according to an embodiment of the present invention is shown.

[0123] Fig.10 A schematic diagram of a radio frequency branch signal processing module according to an embodiment of the present invention is shown.

[0124] like Fig. 9As shown, when the number of quantum bits is expanded on a large scale, the RF reflection measurement system includes signal sources 1, m delay modules 10, m RF branch signal processing modules 11, amplitude and phase controllers 4, mixers 5, signal processing units 6, and power synthesizers 9.

[0125] like Fig.10 As shown, each RF branch signal processing module 11 includes a power divider 2, a filtering unit 8 and a delay line unit 3.

[0126] like Fig. 9 and Fig.10 As shown in the RF reflection measurement system, The output ends of the signal sources 1 are respectively connected to the input ends of the m delay modules 10, the output ends of the m delay modules 10 are connected to the input ends of the m RF branch signal processing modules 11, the output ends of the m RF branch signal processing modules 11 are connected to the input end of the power synthesizer 9, and the output end of the power synthesizer 9 is connected to the RF signal input port of the mixer 5.

[0127] In this RF reflection measurement system, The output end of the signal source 1 is connected to the input end of the amplitude and phase controller 4, and the output end of the amplitude and phase controller 4 is connected to the local oscillator signal input port of the mixer 5. The output end of the mixer 5 is connected to the input end of the signal processing unit 6.

[0128] In each RF branch signal processing module 11 , the filtering unit 8 includes n filters, and the delay line unit 3 includes n delay lines.

[0129] In the RF reflection measurement system, the output end of each delay module 10 is connected to the input end of the power divider 2 in each RF branch signal processing module 11, the power divider 2 divides the RF branch into n measurement channels, the n output ends of the power divider 2 are respectively connected to the input ends of the n filters included in the filtering unit 8, and the output ends of the n filters are connected to the input ends of the n delay lines included in the delay line unit 3.

[0130] The m signal sources 1 are configured to synchronously generate frequency modulated continuous wave signals.

[0131] The m delay modules 10 are configured to control the transmission time of the FM continuous wave signal from the signal source 1 to the power divider 2 to ensure that the power dividers 2 included in the multiple RF branch signal processing modules 11 are in the same phase state when receiving the FM continuous wave signal.

[0132] The power divider 2 in each RF branch signal processing module 11 is configured to divide the frequency modulated continuous wave signal into n RF branch signals.

[0133] The filtering unit 8 is used to filter the n RF branch signals based on the center frequency to obtain filtered RF branch signals, wherein the center frequency is configured to match the resonant frequency of the n quantum bits included in the quantum chip.

[0134] The delay line unit 3 is configured to adjust the delay time and amplitude of each of the n filtered RF branch signals to obtain n RF signals. The n RF signals in each RF branch signal processing module 11 are incident on the n qubits of the quantum chip inside the dilution refrigerator, and are reflected by the n qubits to obtain n RF reflection sub-signals.

[0135] The power synthesizer is used to synthesize n RF reflection sub-signals outputted by the m RF branch signal processing modules 11 to obtain m RF reflection signals, and then synthesize the m RF reflection signals into one RF reflection signal RF to be transmitted to the mixer 5 .

[0136] The amplitude and phase controller 4 is used to The phase and amplitude of the local oscillator branch signal generated by a signal source are adjusted to obtain a local oscillator signal LO that is coherent with the RF branch signal.

[0137] The mixer is used to mix the local oscillator signal LO and a radio frequency reflection signal RF formed by reflection from the quantum chip to obtain an intermediate frequency signal IF.

[0138] The signal processing unit 6 is used to perform spectrum analysis and signal transformation on the intermediate frequency signal IF to obtain measurement information of the quantum chip.

[0139] According to an embodiment of the present invention, in a very large-scale quantum bit system, due to the large number of quantum bits, each quantum bit may require an independent control signal or measurement signal. Based on this, in order to ensure that these signals can act on the corresponding quantum bits correctly, in the embodiment of the present invention, in the case of ultra-large-scale expansion of quantum bits, the RF reflection measurement device of the quantum chip can be used as a basic unit, and the RF reflection measurement can be realized by synchronizing multiple signal sources and setting different delay differences between the signal source and the power divider, thereby achieving resource saving.

[0140] In addition, an embodiment of the present invention compensates for the delay by adding a delay module before each RF branch signal processing module, so that each n-bit unit can be distinguished based on each delay module, thereby cooperating with the delay line unit to achieve accurate and fast addressing of each quantum bit in the n-bit unit under a large-scale expansion scheme.

[0141] Fig.11 A flow chart of a method for measuring radio frequency reflection of a quantum chip according to an embodiment of the present invention is shown.

[0142] like Fig.11 As shown, the radio frequency reflection measurement method includes operations S1110 to S1160.

[0143] In operation S1110 , in response to a radio frequency reflection measurement request for a quantum chip, a frequency modulated continuous wave signal generated by a signal source is acquired.

[0144] In operation S1120, the frequency modulated continuous wave signal is divided into a local oscillator branch signal and a radio frequency branch signal.

[0145] In operation S1130, the phase and amplitude of the local oscillator branch signal are adjusted to obtain a local oscillator signal that is coherent with the radio frequency branch signal.

[0146] In operation S1140, the delay time of the radio frequency branch signal is adjusted.

[0147] In operation S1150, the local oscillation signal and the radio frequency reflection signal formed by reflection of the quantum chip are mixed to obtain a mixed signal.

[0148] In operation S1160, spectrum analysis and signal transformation are performed on the mixed signal to obtain measurement information of the quantum chip.

[0149] It should be noted that the RF reflection measurement method part of the quantum chip in the embodiment of the present invention corresponds to the RF reflection measurement device part of the quantum chip in the embodiment of the present invention. The description of the RF reflection measurement method part of the quantum chip specifically refers to the RF reflection measurement device part of the quantum chip, which will not be repeated here.

[0150] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation 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 these combinations and / or combinations fall within the scope of the present invention.

[0151] 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 radio frequency reflection measurement device for a quantum chip, characterized in that: include: A signal source, used to generate a frequency modulated continuous wave signal, wherein a frequency adjustment range of the frequency modulated continuous wave signal is determined based on a resonant frequency of a quantum bit included in the quantum chip; A power divider, used for dividing the frequency modulated continuous wave signal into a local oscillator branch signal and a radio frequency branch signal; An amplitude and phase controller, used to adjust the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; A delay line unit, used for adjusting the delay time of the radio frequency branch signal to obtain a radio frequency signal, wherein the radio frequency signal is incident on a quantum chip inside the dilution refrigerator; A mixer, used for mixing the local oscillator signal and the radio frequency reflection signal formed by reflection of the quantum chip to obtain a mixed signal; A signal processing unit, configured to perform low-pass filtering on the mixed signal to obtain an intermediate frequency signal, perform spectrum analysis and signal transformation on the intermediate frequency signal, and obtain measurement information of the quantum chip; Wherein, the signal processing unit is configured as: Performing spectrum analysis on the intermediate frequency signal to determine the amplitude and phase corresponding to the frequency of the intermediate frequency signal, wherein the frequency of the intermediate frequency signal is determined based on the frequency modulation slope of the signal source and the delay time of the radio frequency branch signal; Determining measurement information of the quantum chip based on the amplitude and phase corresponding to the frequency of the intermediate frequency signal, wherein the measurement information of the quantum chip includes amplitude information and phase information of a reflection coefficient corresponding to the quantum chip; Wherein, the expression of the local oscillator signal is as follows: （1）； Wherein, LO represents the local oscillator signal; Indicates the starting frequency of the frequency modulated continuous wave signal; represents the frequency modulation slope of the signal source; a represents the amplitude of the local oscillator signal; The expression of the radio frequency reflection signal is as follows: （2）； In the formula, represents the radio frequency reflection signal, A represents the amplitude of the radio frequency reflection signal, represents the reflection coefficient, Indicates the delay time of the radio frequency branch signal; The expression of the mixing signal is as follows: （3）； In the formula, represents the mixed signal; The expression of the intermediate frequency signal is as follows: （4）； In the formula, represents the intermediate frequency signal; The expression of the intermediate frequency signal frequency is as follows: （5）； In the formula, represents the frequency of the intermediate frequency signal; The amplitude information expression of the reflection coefficient is as follows: （6）； In the formula, represents the amplitude information of the reflection coefficient, Indicates that the intermediate frequency signal is The range of the place.

2. The radio frequency reflection measurement device according to claim 1, characterized in that: Determining the measurement information of the quantum chip based on the amplitude and phase corresponding to the signal frequency of the intermediate frequency signal includes: Calculate the amplitude information of the reflection coefficient based on the amplitude corresponding to the signal frequency of the intermediate frequency signal, the amplitude of the radio frequency branch signal, and the amplitude of the local oscillator branch signal; The phase information of the reflection coefficient is calculated based on the phase corresponding to the signal frequency of the intermediate frequency signal and the additional phase.

3. The radio frequency reflection measurement device according to claim 1, characterized in that: The radio frequency reflection measurement device further includes an attenuator unit, The attenuator unit is configured to be connected to the output end of the delay line unit, and the attenuator unit is used to adjust the signal amplitude of the radio frequency signal.

4. The radio frequency reflection measurement device according to claim 1, characterized in that: The radio frequency reflection measurement device further includes a filtering unit, The filtering unit is configured to be connected to the output end of the power divider, and is used to filter the RF branch signal based on a center frequency to obtain a filtered RF branch signal, wherein the center frequency is configured to match the resonant frequency of the quantum bits contained in the quantum chip.

5. The radio frequency reflection measurement device according to claim 4, characterized in that: The power divider is further configured to divide the frequency modulated continuous wave signal into the local oscillator branch signal and multiple radio frequency branch sub-signals; The filtering unit includes a plurality of filters, and the plurality of filters are used to filter the plurality of radio frequency branch sub-signals based on respective center frequencies to obtain the plurality of filtered radio frequency branch sub-signals, wherein the center frequencies of the plurality of filters are respectively configured to match the respective resonant frequencies of the plurality of quantum bits; The delay line unit includes a plurality of delay lines, and the plurality of delay lines are used to adjust the delay time of the multi-path filtered RF branch sub-signals to obtain a plurality of RF sub-signals; wherein the plurality of RF sub-signals are respectively incident on the quantum chip inside the dilution refrigerator, and are reflected by a plurality of quantum bits included in the quantum chip to obtain a plurality of RF reflection sub-signals; The radio frequency reflection measurement device further includes a power synthesizer, and the power synthesizer is configured to perform synthesis processing on the multi-path radio frequency reflection sub-signals to obtain the radio frequency reflection signal.

6. A radio frequency reflection measurement system for a quantum chip, characterized in that: The radio frequency reflection measurement system includes multiple signal sources, multiple radio frequency branch signal processing modules, an amplitude and phase controller, a mixer, and a signal processing unit, wherein each of the radio frequency branch signal processing modules includes a power divider and a delay line unit; The plurality of signal sources are configured to synchronously generate frequency modulated continuous wave signals; The power divider is used to divide the frequency modulated continuous wave signal into multiple radio frequency branch signals; The delay line unit is used to adjust the delay time of the multi-channel radio frequency branch signal to obtain a radio frequency signal, wherein the multi-channel radio frequency signal is incident on the quantum chip inside the dilution refrigerator; The amplitude and phase controller is used to adjust the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; The mixer is used to mix the local oscillator signal and the radio frequency reflection signal formed by reflection of the quantum chip to obtain a mixed signal; The signal processing unit is used to perform low-pass filtering on the mixed signal to obtain an intermediate frequency signal, perform spectrum analysis and signal transformation on the intermediate frequency signal, and obtain measurement information of the quantum chip; Wherein, the signal processing unit is configured as: Performing spectrum analysis on the intermediate frequency signal to determine the amplitude and phase corresponding to the frequency of the intermediate frequency signal, wherein the frequency of the intermediate frequency signal is determined based on the frequency modulation slope of the signal source and the delay time of the radio frequency branch signal; Determining measurement information of the quantum chip based on the amplitude and phase corresponding to the frequency of the intermediate frequency signal, wherein the measurement information of the quantum chip includes amplitude information and phase information of a reflection coefficient corresponding to the quantum chip; Wherein, the expression of the local oscillator signal is as follows: （1）； Wherein, LO represents the local oscillator signal; Indicates the starting frequency of the frequency modulated continuous wave signal; represents the frequency modulation slope of the signal source; a represents the amplitude of the local oscillator signal; The expression of the radio frequency reflection signal is as follows: （2）； In the formula, represents the radio frequency reflection signal, A represents the amplitude of the radio frequency reflection signal, represents the reflection coefficient, Indicates the delay time of the radio frequency branch signal; The expression of the mixing signal is as follows: （3）； In the formula, represents the mixed signal; The expression of the intermediate frequency signal is as follows: （4）； In the formula, represents the intermediate frequency signal; The expression of the intermediate frequency signal frequency is as follows: （5）； In the formula, represents the frequency of the intermediate frequency signal; The amplitude information expression of the reflection coefficient is as follows: （6）； In the formula, represents the amplitude information of the reflection coefficient, Indicates that the intermediate frequency signal is The range of the place.

7. The radio frequency reflection measurement system according to claim 6, characterized in that: The radio frequency reflection measurement system also includes a plurality of delay modules. Each of the delay modules is used to control the transmission time of the frequency modulated continuous wave signal from the signal source to the power divider, so as to ensure that the power dividers included in the multiple RF branch signal processing modules are in different phase states when receiving the frequency modulated continuous wave signal; The radio frequency reflection measurement system further includes a plurality of power synthesizers, and the plurality of power synthesizers are configured to perform synthesis processing on multiple radio frequency reflection signals to obtain the radio frequency reflection signals.

8. A method for measuring radio frequency reflection of a quantum chip, applied to the radio frequency reflection measurement device as described in any one of claims 1 to 5 or the radio frequency reflection measurement system as described in any one of claims 6 to 7, characterized in that: The radio frequency reflection measurement method comprises: In response to a radio frequency reflection measurement request for the quantum chip, acquiring a frequency modulated continuous wave signal generated by a signal source, wherein a frequency adjustment range of the frequency modulated continuous wave signal is determined based on a resonant frequency of a quantum bit included in the quantum chip; The frequency modulated continuous wave signal is divided into a local oscillator branch signal and a radio frequency branch signal; Adjusting the phase and amplitude of the local oscillator branch signal to obtain a local oscillator signal that is coherent with the radio frequency branch signal; Adjusting the delay time of the radio frequency branch signal to obtain a radio frequency signal, wherein the radio frequency signal is incident on the quantum chip inside the dilution refrigerator; Mixing the local oscillator signal and the radio frequency reflection signal formed by reflection of the quantum chip to obtain a mixed signal; Performing spectrum analysis and signal transformation on the mixed signal to obtain measurement information of the quantum chip; The mixing signal is subjected to spectrum analysis and signal transformation to obtain measurement information of the quantum chip, including: Based on the frequency modulation slope of the signal source and the delay time of the radio frequency branch signal, performing spectrum analysis on the mixed signal to determine the signal frequency of the mixed signal, wherein the delay time of the radio frequency branch signal is generated by a delay line unit; Based on the signal frequency of the mixing signal, determining an amplitude and a phase corresponding to the signal frequency of the mixing signal; Based on the amplitude and phase corresponding to the signal frequency of the mixing signal, the measurement information of the quantum chip is determined, wherein the measurement information of the quantum chip includes the amplitude information and the phase information of the reflection coefficient corresponding to the quantum chip.

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