Superconducting frequency multiplexing reading method capable of being digitally regulated and controlled

Abstract

The invention discloses a superconducting frequency reuse reading method capable of being digitally regulated and controlled, which is characterized in that a plurality of resonance circuits are connected between a signal input end and a signal output end of a transmission feeder line, and the resonance circuits are connected with a superconducting nanowire three-terminal device to form a resonance unit; a detection signal of the SNSPD independent of the resonance unit is connected to the superconducting nanowire three-terminal device, and a detection response signal of the SNSPD generates a readable microwave signal at the signal output end of the transmission feeder line. According to the invention, reading can be carried out aiming at a very weak SNSPD signal, the response position and number of the SNSPD can be synchronously identified, frequency drift does not exist, the input pulse of the SNSPD can realize a digital 0 / 1 switching effect by switching on and off a superconducting nanowire three-terminal device, the basic characteristics of the SNSPD itself are not damaged, a circuit with a relatively high resonant frequency can be formed, and the signal processing efficiency is improved. The method has the advantages of very low read error rate, more flexible regulation and control mode and higher output signal-to-noise ratio.

Description

Technical Field

[0001] The present invention relates to a method for reading out an SNSPD array by using frequency multiplexing, and particularly to a digitally controllable superconducting frequency multiplexing readout method. Background Art

[0002] Superconducting nanowire single photon detectors (hereinafter referred to as SNSPDs) are currently the detectors with the most excellent comprehensive performance and play a very important role in deep space communication, lidar, optical quantum computing, mid-infrared imaging and other fields. SNSPDs usually use an array arrangement to further improve their detection performance; reading out the SNSPD array has always been a major challenge.

[0003] Among them, the scheme of reading out the SNSPD array by using frequency multiplexing has been developed to a certain extent. It mainly uses superconducting nanowires to construct lumped inductors and capacitors to realize a circuit with a fixed resonant frequency. By changing the inductor or capacitor parameters, a circuit with multiple resonant frequencies can be constructed. These circuits are connected to both sides of a transmission feeder with a characteristic impedance of 50Ω. The detector part may be included in the resonant circuit or can be used as a separate detector; when it responds, the generated output signal will deteriorate the Q value of the resonant circuit, and the originally stored resonant signal is released to the output port through the transmission feeder. Through subsequent waveform or phase processing, it can be determined whether the corresponding resonant circuit responds to a single photon signal. Currently, the main methods for reading out the SNSPD array by using frequency multiplexing are as follows:

[0004] (2) To improve the above problems, Steffen Doerner et al. optimized the frequency drift and other problems of the resonant circuit in 2017, designed 16 detectors, each with a different resonant frequency, and coupled the 16 detectors into the same transmission feeder to realize the optical response of 16 detectors read out by a single readout feeder. Although any one of the 16 detector pixels can be read out by using a single wire for reading, which simplifies the readout circuit; however, the efficiency of the detector array is still very low, and it is difficult to achieve a high detection efficiency.

[0005] (3) Bias the detector by using a DC method. At the same time, the detector and the capacitive element form a resonant circuit to form a detector array with 16 different resonant frequencies. By using Fourier transform, it can be judged whether a certain detector responds in the frequency domain. This method improves the photosensitive area of the detector. The problem with this readout method is that the frequency range used is relatively low, about several hundred megahertz. When the array is expanded, the second-order resonant frequency of the resonant circuit needs to be considered. Therefore, the available frequency bandwidth is very narrow, and the number of detectors that can be expanded is limited.

[0006] (4) By utilizing the dependence of dynamic inductance on the bias current, a dynamic inductance parameter upconverter is designed. The current after the SNSPD response will flow through this upconverter, causing a change in the resonant frequency. By measuring the phase change of the output waveform, it is possible to determine whether a photon has been responded to. Although this readout method overcomes the problem of low efficiency of the SNSPD detector existing in the above two methods, since the upconverter is prone to large frequency drift after receiving the input current, when multiple upconverters exist simultaneously, frequency crosstalk is very likely to occur. Summary of the Invention

[0007] In view of the above problems existing in the prior art, the present invention provides a digitally controllable superconducting frequency multiplexing readout method.

[0008] To achieve the above object, the present invention provides the following technical solution: A digitally controllable superconducting frequency multiplexing readout method, in which a resonant circuit is connected between the signal input end and the signal output end of the transmission feeder. The frequency signal corresponding to the resonant circuit is transmitted to the resonant circuit through the transmission feeder. The resonant circuit is connected to a superconducting nanowire three-terminal device to form a resonant unit. The detection signal of a superconducting nanowire single-photon detector (SNSPD) independent of the resonant unit is connected to the signal input end of the superconducting nanowire three-terminal device to trigger the superconducting nanowire three-terminal device. The superconducting nanowire three-terminal device serves as an SNSPD output pulse discriminator after photon response; when receiving the pulse of the SNSPD, the superconducting nanowire three-terminal device changes from the superconducting state to the normal state, generating a hot spot resistance; when there is no input signal, the superconducting nanowire three-terminal device remains in the superconducting state. This control method corresponds to the control effects of digital "0" and "1"; the detection response signal of the superconducting nanowire single-photon detector SNSPD is judged by the superconducting nanowire three-terminal device, and a readable microwave signal is generated at the signal output end of the transmission feeder.

[0009] Further, several resonant units with different resonant frequencies are connected to the same transmission feeder. After the response signal of the superconducting nanowire single-photon detector SNSPD is judged by the superconducting nanowire three-terminal device, microwave signals with different frequencies are generated at the signal output end of the transmission feeder. Based on this microwave signal, the response position and number of the superconducting nanowire single-photon detector SNSPD can be read out simultaneously.

[0010] Further, the resonant circuit includes a first capacitor, a second capacitor, and an inductor. The first capacitor is connected to the transmission feeder. The second capacitor and the inductor are connected in parallel and then connected in series with the first capacitor, and then connected to the superconducting nanowire three-terminal device. The resonant frequency can be changed by changing the value of the inductor or the second capacitor. The superconducting nanowire three-terminal device, inductor, capacitor, and transmission feeder are all prepared from superconducting thin films such as niobium nitride, niobium titanium nitride, etc.

[0011] Further, the superconducting nanowire three-terminal device includes, but is not limited to, nTron. When the superconducting nanowire three-terminal device is nTron, the drain terminal of nTron is connected to the resonant circuit, the detection signal of the superconducting nanowire single-photon detector SNSPD is connected to the gate terminal of nTron, and the source terminal of nTron is connected to ground.

[0012] Further, a square-wave bias signal is applied to the drain terminal of nTron.

[0013] Further, the readout method of the resonant circuit includes, but is not limited to, using Fourier transform to convert the output signal of the transmission feeder, observing whether there is a response by judging the amplitude within the frequency range, and synchronously identifying the response position and number of the superconducting nanowire single-photon detector SNSPD by judging the amplitude change of the frequency.

[0014] Further, by using a microwave signal source and a mixer circuit, through frequency up-conversion and down-conversion, the obtained output signal is Fourier-transformed and the amplitude change is observed in the frequency domain to judge whether a response occurs, realizing signal input and signal reading of the resonant circuit.

[0015] Further, the mixer circuit includes a DAC board, an ADC board, a first IQ mixer, a second IQ mixer, an attenuator, a cryogenic amplifier, a room-temperature amplifier, two low-pass filters, a first local oscillator driver, and a second local oscillator driver; first, a fundamental wave signal is generated by the microwave signal source and then power-amplified by the first local oscillator driver, and then up-converted with a series of sine signals of different frequencies generated by the DAC board through the first IQ mixer to obtain the frequency signals corresponding to the resonant circuit; these frequency signals are attenuated by the attenuator and then connected to the input end of the transmission feeder to bias the microwave signals for each resonant unit; at the output end of the transmission feeder, the signal is first amplified by the cryogenic amplifier, then passed through the room-temperature amplifier and connected to the second IQ mixer, and down-converted with the fundamental wave signal power-amplified by the second local oscillator driver to demodulate the signal, and then the two output signals pass through the two low-pass filters and are connected to the input end of the ADC board to realize signal acquisition.

[0016] Further, the signal transfer method between the superconducting nanowire single-photon detector SNSPD and the resonant unit includes, but is not limited to, a circuit connection method for realizing signal transfer with the resonant circuit through a resistance interface; when using a resistance interface connection, the output signal of the superconducting nanowire single-photon detector SNSPD passes through a grounding resistor R t1 and resistor R g1 and then is connected to the signal input end of the superconducting nanowire three-terminal device.

[0017] Further, the grounding resistor Rt1 Resistance value >> Resistance R g1 resistance value.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention uses nTron devices to sense SNSPD signals. nTron has the advantages of high sensitivity and simple preparation process, and can read very weak SNSPD signals. In addition, since nTron itself is a component unit of the resonant circuit, its channel end inductance is very small, so the resonant frequency of each resonator has almost no frequency drift introduced by the current bias applied at the channel end, which prevents the resonator from facing frequency crosstalk and other problems due to frequency drift.

[0020] 2. In the prior art, the SNSPD itself is used as part of the resonator, and the SNSPD usually requires a relatively large area to ensure detection efficiency. The SNSPD has a large inductance that makes the resonator frequency very low. Considering the second-order resonant frequency, this makes the frequency bandwidth utilization rate low, which is not conducive to large-scale expansion within a limited frequency bandwidth. The present invention introduces nTron, which separates the SNSPD and the resonant circuit on the one hand, retains the high absorption rate and detection efficiency of the SNSDP itself, and does not damage the basic characteristics of the SNSPD itself. In addition, the channel end inductance of nTron is very small, and it can form a circuit with a higher resonant frequency. For example, the resonant frequency can be set at 4-8GHz, and the bandwidth range that can be used is 4GHz. This frequency range can realize a resonant circuit of thousands or even tens of thousands of pixels, and has very strong scalability.

[0021] 3. nTron is a digital logic threshold judger, which can distinguish the input of SNSPD similar to "0" and "1". This judgment method can ensure that such a microwave circuit has a very low readout bit error rate. In addition, nTron uses a square wave bias method, which can control the working speed of nTron and make the regulation method more flexible.

[0022] 4. This microwave circuit is very suitable for reading out the SNSPD array, so as to realize the synchronous detection of the position and number of multiple SNSPDs. This is because each resonator has a different resonant frequency. After the electrical signal of each SNSPD response is judged by nTron, a microwave signal of different frequency will be generated at the output end. After the signal is collected and Fourier transform is performed, the amplitude change of the frequency can be judged at the same time, so as to synchronously identify the response position and number of the SNSPD.

[0023] 5. Additionally, in this resonant circuit, nTron mainly operates in the latch mode. Utilizing the latch mode of nTron can ensure that after nTron receives a signal from the SNSPD, it can maintain a stable resistance state (usually several thousand ohms), thereby enabling more signals to be transmitted to the output end and achieving a higher signal-to-noise ratio at the output.

[0024] 6. nTron, the inductor, the capacitor, and the transmission feeder in the resonator can all be fabricated using the same superconducting thin film material as the SNSPD. All the devices can be fabricated through a single micro-nano processing technology, and the compatibility of the fabrication process is very high. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a circuit schematic diagram of the frequency readout superconducting nanowire single photon detector array described in the present invention;

[0026] Figure 2 is a detailed design diagram of a single resonator of the present invention;

[0027] Figure 3 is the S 21 curve corresponding to the resonant circuit of 32 pixels described in the present invention;

[0028] Figure 4 is the coupling circuit structure diagram of a single SNSPD and a single resonant circuit described in the present invention patent;

[0029] Figure 5 is a system block diagram for applying and reading out microwave signals of the resonant circuit;

[0030] Figure 6 are the time-domain waveforms before and after the resonant unit with a resonant frequency of 4.190 GHz in the resonant circuit responds to the input signal and the frequency amplitude transformation after Fourier transform.

[0031] Markings in the figure: 1: 50-ohm transmission feeder; 2: interdigital capacitor C1; 3: GND; 4: interdigital capacitor C2; 5: inductor L1; 6: nTron device; 7: gate terminal of nTron; 8: channel terminal of nTron; 9: bias terminal of nTron; 10: connection point of capacitor C2 and inductor L1; 11: GND. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be further described in detail below with reference to the accompanying drawings.

[0033] The present invention utilizes a superconducting nanowire three-terminal device (hereinafter referred to as nTron), combines inductors, capacitors, etc. to construct a resonant circuit, so as to realize the synchronous detection of the position and number information of the SNSPD array. The types of SNSPD include not only the conventional array-type SNSPD, but also the waveguide-integrated SNSPD. The present invention is a general readout method for SNSPD. The overall structure of this frequency readout circuit is as Figure 1 shown. The characteristic impedance of the transmission feeder used is 50 ohms, and it is realized in the form of a coplanar waveguide. Multiple resonant circuits can be connected to both ends of the transmission feeder. Here, a circuit with a characteristic frequency of f1 is taken as an example to explain the circuit structure. This resonant circuit includes a capacitor C1 connected to the transmission feeder. Capacitor C2 and inductor L1 are connected in parallel and then connected in series with capacitor C1, and then connected to the drain terminal of nTron. A square-wave bias signal is applied to the drain terminal of nTron to bias nTron under conditions that are easily triggered. The input signal is connected to the gate terminal of nTron to trigger nTron, and the source terminal of nTron is connected to ground.

[0034] In the working mode, a square-wave signal is applied to the drain terminal of nTron to realize signal biasing. On the one hand, each nTron can work in the latched mode, so as to be able to generate a stable hot-spot resistance state. On the other hand, a digital control method can be realized, which can greatly improve the working speed of nTron and the entire resonant circuit. When the entire resonant circuit is in the superconducting state, this resonant circuit will generate a characteristic resonant frequency f1. When the capacitance C1, capacitance C2 and the structure of nTron of this resonant circuit remain unchanged, by changing the inductor L1 of the resonant circuit, as Figure 1 shown, resonant circuits with different resonant frequencies f1, f2, f3, and even f N can be obtained. At this time, the inductor values will be different. Of course, the resonant frequency can also be changed by other means such as changing the capacitance value in the resonator. In this way, multiple circuits with different resonant frequencies can be connected to the same transmission feeder, Figure 2Device picture and device detail example for a single resonator circuit. The device mainly includes a 50-ohm transmission feeder 1, a coplanar capacitor C12, GND3, a coplanar capacitor C24, an inductor L15, and an nTron device 6. The nTron device 6 mainly includes the gate terminal 7 of nTron, the channel terminal 8 of nTron, the bias terminal 9 of nTron, the connection point 10 between capacitor C2 and inductor L1, and GND11. Specifically, the gap of the coplanar capacitor C1 in the resonator is 1 µm, the line width is 1 µm, the gap of the coplanar capacitor C2 is 500 nm, and the line width is 1 µm; the width of the inductor L1 is 1 µm; the width of the channel terminal of nTron is 120 nm, and the width of the gate terminal is 50 nm. It should be noted that the basic elements in the constructed resonant circuit, inductors and capacitors, can have various geometric structures and nanoscale dimensions, and the above is only an example. The critical currents corresponding to the gate terminal and channel terminal of nTron are 12 µA and 50 µA respectively.

[0035] When all resonators are in the superconducting state, by measuring the transmission coefficient S at both ends of the transmission feeder 21 , multiple resonant peaks can be obtained. Figure 3 Figure (a) of 21 shows the S of 32 resonant circuits Figure 3 , and 32 obvious resonant peaks appear, corresponding to 32 resonant frequencies. When the input signal received by the resonator with a resonant frequency of 4.190 GHz is large enough, after the gate terminal of nTron undergoes a transition from the superconducting state to the normal state, it will cause a large transient resistance to also occur at the channel terminal of nTron. At this time, the resonant peak of the resonator will disappear and become flat, as shown in 21 Figure (b). When no signal is received, the S of this resonant peak 21 is approximately 15.5 dB in magnitude, and when a signal is received, the S Figure 1 becomes about 20 dB, showing an amplitude change of 4.5 dB. When the output signal of the 50-ohm transmission feeder passes through a cryogenic amplifier and a room-temperature amplifier, after Fourier transform, the amplitude change corresponding to the resonant frequency point can be observed on the scale of the frequency domain, thereby determining whether the resonator responds. As shown in

[0036] The present invention uses a resistive interface circuit to couple the readout signal of the SNSPD to the gate terminal of nTron in this resonant circuit. Figure 4 shows the schematic diagram of a single SNSPD coupling signals to resonance through a resistive structure. The output signal of the SNSPD passes through a grounded resistor R t1 and resistor R g1 and then is connected to the gate port of nTron. Resistor RG1 It can isolate the SNSPD signal from the DC current of nTron and prevent the entire circuit from malfunctioning due to the crosstalk of DC signals. Resistor R N1 can ensure that when the SNSPD recovers from the normal state to the superconducting state after detecting photons, it provides a current loop to ensure that the SNSPD can recover to the superconducting state by itself. In addition, for the interface resistor, the resistor R t1 >>R g1 so as to ensure that most of the signals of the SNSPD can be coupled to the gate terminal of nTron. It should be noted that the signal coupling method between the SNSPD and the resonant circuit is not limited to the resistor interface described in this embodiment, but also includes various signal coupling methods between the SNSPD and nTron realized through resistors, inductors, and capacitors.

[0037] The present invention uses a microwave source and a mixing circuit to achieve signal input and signal reading of the resonant circuit. The overall system block diagram is as Figure 5 shown, including a DAC board, an ADC board, two IQ mixers, a microwave signal source, an attenuator, a cryogenic RF amplifier, a room-temperature amplifier, two low-pass filters, and two intrinsic signal drivers. First, a fundamental wave signal is generated by the microwave signal source and then amplified in power through the intrinsic driver 1. After that, it is up-converted through the IQ mixer 1 with a series of sine signals of different frequencies generated by the DAC board to obtain a series of frequency signals corresponding to the resonant circuit. These frequency signals are attenuated by the attenuator and then connected to the input end of a 50-ohm transmission feeder to bias each resonator with microwave signals. At the output end of the 50-ohm transmission feeder, the signal is first amplified by the cryogenic amplifier, then connected to the IQ mixer 2 after a stage of room-temperature amplifier, and down-converted with the fundamental wave signal amplified in power through the intrinsic driver 2 to achieve signal demodulation. Then, the two output signals pass through two low-pass filters and are connected to the input end of the ADC board to achieve signal acquisition.

[0038] The output signal obtained through the above system can be observed for amplitude changes in the frequency domain after Fourier transform to determine whether a response occurs. Figure 6 Figure (a) shows the time-domain signal collected by the ADC board when there is no signal input at the input end of nTron for a resonant circuit with a resonant frequency of 4.190 GHz, Figure 6 Figure (b) shows the result of the time-domain signal after down-conversion and Fourier transform, with a corresponding frequency of 130 MHz and an equivalent amplitude of 1.6; Figure 6 Figure (c) shows the time-domain signal collected by the ADC board when there is a signal input at the input end of nTron for a resonant circuit with a resonant frequency of 4.190 GHz; the equivalent amplitude of the signal corresponding to a frequency signal of 130 MHz after Fourier transform is 3.0, asFigure 6 as shown in (d) of

[0039] Within the frequency range, the frequency points of each resonator are separated and there is no interference between them. After multiple SNSPDs respond simultaneously and their output signals are sensed by the resonator circuit, through Figure 4 the signal generation and reception system, and after Fourier transform, it is possible to judge the number of responding SNSPDs and their corresponding positions within the frequency range. This readout method has the ability to resolve both position and number. It should be noted that the readout method of the present invention is not limited to the use of Fourier transform to convert the output signal and observe the response by judging the amplitude within the frequency range as described in this embodiment. Other readout methods can also be used. For example, phase information can be used to judge whether there is a signal response.

[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For example, the resonator circuit in this embodiment uses nTron to receive the optical response signal from the SNSPD, but it can also be implemented with another type of superconducting nanowire three-terminal device, namely hTron (for example, the thermal effect of the input signal is used to trigger and respond to the device), and both planar hTron and three-dimensional hTron can be used to replace the nTron structure. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A digitally controllable superconducting frequency multiplexing readout method, characterized in that: A resonant circuit is connected between the signal input end and the signal output end of the transmission feeder, a frequency signal corresponding to the resonant circuit is transmitted to the resonant circuit through the transmission feeder, the resonant circuit is connected to a superconducting nanowire three-terminal device to form a resonant unit, a detection signal of a superconducting nanowire single photon detector SNSPD independent of the resonant unit is connected to the signal input end of the superconducting nanowire three-terminal device to trigger the superconducting nanowire three-terminal device, and the superconducting nanowire three-terminal device serves as an SNSPD output pulse discriminator after a photon response; When receiving a pulse from the SNSPD, the superconducting nanowire three-terminal device changes from a superconducting state to a normal state, generating hotspot resistance; when there is no input signal, the superconducting nanowire three-terminal still maintains a superconducting state. This control method corresponds to the control effect of digital "0" and "1"; The detection response signal of the superconducting nanowire single photon detector (SNSPD) is judged by the superconducting nanowire three-terminal device, and a microwave signal with a significantly changed output amplitude and readable is generated at the signal output end of the transmission feeder.

2. A digitally controllable superconducting frequency multiplexing readout method according to claim 1, characterized in that: Several resonant units with different resonant frequencies are connected to the same transmission feeder. The response signal of the superconducting nanowire single-photon detector SNSPD passes through the superconducting nanowire three-terminal device. The superconducting nanowire three-terminal device judges the input signal to generate a hotspot resistor. The hotspot resistor transmits the resonant signal originally stored in the resonator to the output end, and generates microwave signals of different frequencies at the signal output end of the transmission feeder. Based on the microwave signal, the response position and number of the superconducting nanowire single-photon detector SNSPD can be read out simultaneously.

3. A digitally controllable superconducting frequency multiplexing readout method according to claim 1, characterized in that: The resonant circuit includes a first capacitor, a second capacitor and an inductor. The first capacitor is connected to a transmission feeder. The second capacitor and the inductor are connected in parallel and then in series with the first capacitor, and then a superconducting nanowire three-terminal device is connected. The resonant frequency can be changed by changing the value of the inductor or the second capacitor. The superconducting nanowire three-terminal device and the capacitor, inductor elements and the transmission feeder are all made of superconducting materials.

4. A digitally controllable superconducting frequency multiplexing readout method according to claim 1, characterized in that: Superconducting nanowire three-terminal devices include but are not limited to nTron. When the superconducting nanowire three-terminal device is nTron, the drain end of nTron is connected to the resonant circuit, the detection signal of the superconducting nanowire single photon detector SNSPD is connected to the gate end of nTron, and the source end of nTron is connected to the ground.

5. A digitally controllable superconducting frequency multiplexing readout method according to claim 4, characterized in that: Apply a square wave bias signal to the drain end of nTron.

6. A digitally controllable superconducting frequency multiplexing readout method according to claim 1, characterized in that: The readout method of the resonant circuit includes but is not limited to converting the output signal of the transmission feeder using Fourier transform, observing whether there is a response by judging the amplitude within the frequency range, and synchronously identifying the response position and number of the superconducting nanowire single photon detector SNSPD by judging the amplitude change of the frequency.

7. A digitally controllable superconducting frequency multiplexing readout method according to claim 1, characterized in that: Using a microwave signal source and a mixing circuit, through frequency up-conversion and down-conversion, the output signal is obtained through Fourier transformation and the amplitude change is observed in the frequency domain to determine whether a response occurs, thereby realizing signal input and signal reading of the resonant circuit.

8. A digitally controllable superconducting frequency multiplexing readout method according to claim 7, characterized in that: The mixing circuit includes a DAC board, an ADC board, a first IQ mixer, a second IQ mixer, an attenuator, a low-temperature amplifier, a normal temperature amplifier, two low-pass filters, a first intrinsic driver and a second intrinsic driver; firstly, a fundamental wave signal is generated by a microwave signal source and then power amplified by the first intrinsic driver, and then up-converted with a series of sinusoidal signals of different frequencies generated by the DAC board through the first IQ mixer to obtain a frequency signal of the corresponding resonant circuit; these frequency signals are attenuated by the attenuator and connected to the input end of the transmission feeder, and the microwave signal is biased for each resonant unit; at the output end of the transmission feeder, the signal is first amplified by a low-temperature amplifier, and then connected to the second IQ mixer after the normal temperature amplifier, and down-converted with the fundamental wave signal power-amplified by the second intrinsic driver to realize signal demodulation, and then the two output signals are connected to the input end of the ADC board through two low-pass filters to realize signal collection.

9. A digitally controllable superconducting frequency multiplexing readout method according to claim 1, characterized in that: The signal transmission method between the superconducting nanowire single photon detector SNSPD and the resonant unit includes but is not limited to a circuit connection method for realizing signal transmission with the resonant circuit through a resistor interface; when the resistor interface is used for connection, the output signal of the superconducting nanowire single photon detector SNSPD passes through the grounding resistor R t1 and resistor R g1 Then it is connected to the signal input terminal of the superconducting nanowire three-terminal device.

10. A digitally controllable superconducting frequency multiplexing readout method according to claim 9, characterized in that: Ground resistance R t1 Resistance value >> Resistance R g1 resistance value.

Images