Superconducting single photon detection system

Abstract

The invention belongs to the field of quantum information, and discloses a superconducting single-photon detection system, which adopts a parallel vertical compact integrated layout, and comprises a superconducting single-photon detector array arranged in a stable low-temperature area in a low-temperature thermostat; the low-temperature thermostat is used for providing and maintaining a vacuum and low-temperature environment required by the working of the superconducting single-photon detector array; the refrigerating machine compressor unit is coupled with the cryostat through a cold head and used for providing cooling capacity; the electric control module is connected with the superconducting single-photon detector array and the refrigerating machine compressor unit and is used for providing bias, signal processing and state monitoring; wherein the superconducting single-photon detector array, the cryostat, the refrigerator compressor unit and the electric control module are compactly integrated in the vertical direction. By means of the highly integrated and miniaturized system layout, the total height of the system does not exceed 0.5 m, the installation specification of the 11U standard is met, and therefore the problems that a traditional system is large in size and difficult to deploy are solved.

Description

Technical Field

[0001] This invention belongs to the field of quantum information, and in particular relates to a superconducting single-photon detection system. Background Technology

[0002] Superconducting nanowire single-photon detectors (SNSPDs), as one of the single-photon detection technologies with the highest detection efficiency and lowest timing jitter, have become core devices in cutting-edge fields such as quantum communication, quantum computing, lidar, and weak light detection. Their working principle is based on the fact that when an extremely fine superconducting nanowire absorbs a single photon, it locally loses its superconductivity, generating a detectable electrical pulse. In related technologies, superconducting single-photon detection systems typically suffer from problems such as large size, complex operation, and high maintenance costs. To achieve the cryogenic environment necessary for superconducting nanowires to operate (usually below their superconducting transition temperature, such as 2-4K), traditional systems mostly rely on bulky liquid helium Dewar flasks or large cryogenic systems. These systems not only occupy a large area and are considerable in weight, but also suffer from problems such as liquid helium consumption, complex maintenance, long start-up times, and difficulty in mobile deployment. This severely limits their application in space-constrained laboratories, field sites, rack-mounted data centers, or future integrated quantum devices. Summary of the Invention

[0003] In view of this, the present invention discloses a superconducting single-photon detection system that can overcome the shortcomings of related technologies.

[0004] To achieve the above objectives, the present invention discloses the following technical solution: According to a first aspect of the present invention, a superconducting single-photon detection system is proposed, the system adopting a parallel vertical compact integrated layout, comprising: A superconducting single-photon detector array is located in the stable low-temperature region inside a cryostat. The cryostat is used to provide and maintain the vacuum and low temperature environment required for the operation of the superconducting single-photon detector array; The refrigeration compressor unit is coupled to the low-temperature thermostat via a cold head to provide cooling capacity; The electronic control module, connected to the superconducting single-photon detector array and the cryo-compressor unit, is used to provide bias, signal processing, and status monitoring. The superconducting single-photon detector array, the cryostat, the cryo-compressor unit, and the electronic control module are compactly integrated in the vertical direction so that the total height of the system does not exceed 0.5 meters and meets the installation specifications of an 11U standard rack. Preferably, the superconducting single-photon detector array is composed of no less than 16 independent superconducting nanowire single-photon detector chips, wherein the superconducting nanowires on the chips are arranged in a meandering grating shape, the width of the superconducting nanowires is 50-150 nanometers, and the material of the superconducting nanowires includes at least one of the following: NbN, NbTiN, MoSi, WSi. Preferably, each of the superconducting single-photon detector chips integrates a distributed Bragg mirror structure below it. The distributed Bragg mirror structure is formed by alternating stacks of high-refractive-index layers and low-refractive-index layers to create an optical microcavity, which is used to enhance the absorption efficiency of photons in a specific wavelength band.

[0005] Preferably, the optical microcavity of the distributed Bragg reflector structure is optimized to have high absorption rates for both TE and TM modes of incident light, so as to achieve an insensitive response to the polarization state of the incident light, wherein the difference in absorption efficiency between TE and TM modes is less than 5%.

[0006] Preferably, the refrigeration compressor unit is a small GM refrigeration unit, with its cold head and compressor arranged in parallel, used to reduce the system temperature to the operating temperature of 2.3K within a preset time.

[0007] Preferably, the vacuum level inside the cryogenic thermostat is maintained below 5 Pa, and multiple layers of thermal insulation material are used for shielding to minimize external heat load.

[0008] Preferably, the electronic control module includes: A precision bias current source is used to provide a bias close to the critical current for the superconducting single-photon detector array; A low-noise preamplifier is used to amplify the weak voltage pulses generated by the detector; A digital signal processing unit based on FPGA or ASIC is used to realize high-speed pulse discrimination and photon counting. Preferably, the system suppresses noise in the following ways: The electronic control module is connected to the superconducting single-photon detector array and the refrigerator compressor unit via a short-distance shielded cable; and / or, The detector array is fixed inside the cryostat using a low-vibration mechanical support structure. Preferably, the electronic control module adopts a replaceable modular design, and can be adapted to superconducting single-photon detector chips of different specifications by changing the interface unit.

[0009] Preferably, the system's performance indicators in the 1550 nm communication band meet the following requirements: The system detection efficiency is no less than 70%; The dark count rate should not exceed 100 per second; The time jitter is no more than 50 picoseconds.

[0010] As can be seen from the above technical solutions, the superconducting single-photon detection system disclosed in this invention is as follows: On the one hand, it directly solves the fundamental problem of "large size and difficult deployment". Through a compact vertical layout, the total system height is kept under 0.5 meters, allowing it to be directly installed in a standard 11U rack, greatly saving space and facilitating rack deployment and integration in space-constrained environments such as laboratories and data centers. On the other hand, the vertical layout facilitates heat dissipation through the natural convection of rising hot air, improving the system's thermal management efficiency and enhancing long-term stability and reliability. Furthermore, the high integration of subsystems such as detectors, cryogenics, cooling, and electrical control reduces external connections and piping, lowering system complexity and failure rate, and improving overall system integrity. Attached Figure Description

[0011] Figure 1 This is a framework diagram of a superconducting single-photon detection system provided in an exemplary embodiment; Figure 2 This is a schematic diagram illustrating the photon response principle of a superconducting nanowire single-photon detector, provided as an exemplary embodiment. Figure 3 This is a flowchart of a superconducting single-photon detection method provided in an exemplary embodiment; Figure 4 This is a schematic structural diagram of a device provided in an exemplary embodiment; Figure 5 This is a block diagram of a superconducting single-photon detection device provided in an exemplary embodiment. Detailed Implementation

[0012] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of one or more embodiments of the present invention as detailed in the appended claims.

[0013] It should be noted that the steps of the corresponding methods in other embodiments are not necessarily performed in the order shown and described in this invention. In some other embodiments, the methods may include more or fewer steps than those described in this invention. Furthermore, a single step described in this invention may be broken down into multiple steps in other embodiments; and multiple steps described in this invention may be combined into a single step in other embodiments.

[0014] Superconducting single-photon detectors (SNSPDs) are core devices in cutting-edge technologies such as quantum communication, quantum computing, and lidar, and have excellent performance characteristics such as high detection efficiency, low dark count, and low time jitter.

[0015] In related technologies, traditional superconducting single-photon detection systems typically employ liquid helium Dewar flasks or large-scale refrigerators, which suffer from problems such as large size, complex operation, and high maintenance costs, making it difficult to meet the needs of space-constrained or portable application scenarios.

[0016] To address the shortcomings of related technologies, this invention proposes a superconducting single-photon detection system.

[0017] Figure 1 This is a framework diagram of a superconducting single-photon detection system provided in an exemplary embodiment. (See diagram for reference.) Figure 1 As shown, the superconducting single-photon detection system adopts a parallel vertical compact integrated layout, including a superconducting single-photon detector array, a cryostat, a refrigerator compressor unit, and an electronic control module.

[0018] The superconducting single-photon detector array is located in the stable low-temperature region inside the cryostat.

[0019] Hotspot model of superconducting nanowire single-photon detector (SNSPD), such as Figure 2 As shown.

[0020] Bias State: The detector operates below 4K, and the nanowire remains in a superconducting state. The bias current is set below the critical current Ic, typically 0.9–0.95 times Ic. Photon Absorption: When a single photon is incident and absorbed by the nanowire, it breaks the superconducting electron pair (Cooper pair), forming a local quasiparticle. Hot Spot Generation: Quasiparticles diffuse and disrupt surrounding Cooper pairs, forming a hot spot in the absorption region, where the local temperature exceeds the critical temperature Tc. Resistance Band Formation: The hot spot region loses its superconductivity, exhibiting finite resistance. Current is forced to bypass the hot spot, leading to an increase in local current density. When the current density exceeds the critical value, the entire nanowire transitions laterally to a resistive state, forming a resistance band. Signal Output: The resistance band generates a voltage pulse on the nanowire, which is amplified by a preamplifier and sent to the signal processing unit. Recovery Process: As electron-phonon heat dissipation and substrate heat conduction occur, the hot spot gradually cools, the nanowire recovers its superconducting state, and the system awaits the next photon.

[0021] The cryostat provides and maintains the vacuum and cryogenic environment required for the operation of the superconducting single-photon detector array. The internal vacuum level of the cryostat is maintained below 3 Pa, and it is shielded with multiple layers of thermal insulation material (such as multiple layers of aluminized polyester film) to minimize external heat load. The internal structure of the cryostat employs a low-vibration mechanical support structure to secure the detector array, reducing mechanical vibration interference to the detectors.

[0022] The compressor unit of the refrigeration unit is a small GM refrigeration unit. The cold head and compressor are arranged in parallel and coupled to a low-temperature thermostat through the cold head to provide cooling capacity. The refrigeration unit can reduce the system temperature to the operating temperature of 2.3K within 8 hours, and the minimum temperature of the cold head can reach 2.3K.

[0023] The electronic control module connects to the superconducting single-photon detector array and the refrigerator compressor unit to provide bias, signal processing, and status monitoring. For example... Figure 4 As shown, the electronic control module includes a precision bias current source, a low-noise preamplifier, and an FPGA-based digital signal processing unit. The precision bias current source provides a bias close to the critical current of the superconducting single-photon detector array; the low-noise preamplifier amplifies the weak voltage pulses generated by the detector; and the FPGA-based digital signal processing unit enables high-speed pulse discrimination and photon counting. The electronic control module is connected to the superconducting single-photon detector array and the refrigerator compressor unit via short-distance shielded cables to reduce external electromagnetic interference.

[0024] The system's modules are compactly integrated vertically, with a total height of 0.45 meters, meeting the installation specifications of an 11U standard rack. The electrical control module adopts a replaceable modular design, allowing for adaptation to different specifications of superconducting single-photon detector chips by changing the interface unit.

[0025] In this embodiment, on the one hand, the fundamental problem of "large size and difficult deployment" mentioned in the background art is directly solved. Through a compact vertical layout, the total system height is controlled to within 0.5 meters, allowing it to be directly installed in a standard 11U rack, greatly saving space and facilitating rack-mount deployment and integration in space-constrained environments such as laboratories and data centers. On the other hand, the vertical layout facilitates heat dissipation by utilizing the convection principle of naturally rising hot air, improving the system's thermal management efficiency and enhancing long-term operational stability and reliability. Furthermore, the high integration of subsystems such as detectors, cryogenics, cooling, and electrical control reduces external connections and piping, lowering system complexity and failure rate, and improving overall system integrity.

[0026] In one embodiment, the superconducting single-photon detector array is composed of no less than 16 independent superconducting nanowire single-photon detector chips, wherein the superconducting nanowires on the chips are arranged in a meandering grating shape, the width of the superconducting nanowires is 50-150 nanometers, and the material of the superconducting nanowires includes at least one of the following: NbN, NbTiN, MoSi, WSi.

[0027] Assuming the superconducting single-photon detector array consists of 32 independent superconducting nanowire single-photon detector chips, with nanowire widths of 80 nanometers and NbTiN material, the total system height is 0.48 meters. In the 1550 nanometer communication band, the system detection efficiency can reach 72%, the dark count rate is 90 per second, and the time jitter is 48 picoseconds.

[0028] A superconducting single-photon detector array is constructed using no fewer than 16 independent superconducting nanowire single-photon detector chips, achieving multi-channel high-density integration to meet the needs of large-scale quantum information processing. The superconducting nanowires are arranged in a meandering grating pattern, with a width of 50-150 nanometers. The materials can be selected from NbN, NbTiN, MoSi, or WSi, which possess excellent superconducting properties and optical characteristics, enabling high detection efficiency and low dark count rate.

[0029] In this embodiment, by integrating no fewer than 16 detector chips, multi-channel high-density integration is achieved, meeting the requirements for large-scale, parallel single-photon detection in applications such as quantum communication and quantum computing, and improving the system's data acquisition throughput. The limited nanowire width and specific superconducting materials (such as NbN, NbTiN, etc.) ensure that the nanowires have high photon absorption efficiency and superconducting properties, laying the material foundation for achieving high system detection efficiency and low dark count rate.

[0030] Furthermore, each of the superconducting single-photon detector chips integrates a distributed Bragg mirror structure below it. The distributed Bragg mirror structure is formed by alternating stacks of high-refractive-index layers and low-refractive-index layers to create an optical microcavity, which is used to enhance the absorption efficiency of photons in a specific wavelength band.

[0031] The DBR structure can reflect photons that have passed through the nanowire back, increasing the effective optical path length of the photons within the nanowire region and causing multiple absorptions, thereby improving the absorption probability of a single incident photon. This directly solves the problem of low coupling efficiency caused by photon escape in traditional structures.

[0032] Specifically, the DBR structure can be composed of alternating layers of high-refractive-index materials (such as Si, n≈3.5) and low-refractive-index materials (such as SiO2, n≈1.45), with each layer having a thickness of approximately 1 / 4 of the target wavelength. The center wavelength can be designed to be 1550 nm, with a reflection bandwidth covering 1400–1700 nm and a reflectivity of no less than 99.99%. Through microcavity reflection, the photon residence time is increased, allowing more photons to interact with the nanowire, thereby improving the detection probability.

[0033] Furthermore, the optical microcavity of the distributed Bragg reflector structure is optimized to have high absorption rates for both TE and TM modes of incident light, so as to achieve an insensitive response to the polarization state of the incident light, wherein the difference in absorption efficiency between TE and TM modes is less than 5%.

[0034] SNSPDs exhibit varying sensitivities to linearly polarized light. To mitigate efficiency fluctuations in TE / TM modes, this embodiment embeds NbN nanowires into a high-refractive-index material (such as Si) to reduce edge electric field mismatch. By optimizing the dielectric layer thickness and refractive index distribution, simulation results show that the absorptivity difference between TE and TM modes is less than 5%, achieving polarization-insensitive detection.

[0035] Traditional SNSPDs are highly sensitive to the polarization state of incident light, which limits their performance in applications with random or unknown polarization states. This invention, through optical design, renders the system insensitive to the polarization state of incident light, improving its versatility and stability in practical applications, and eliminating the need for complex polarization control equipment.

[0036] In one embodiment, the refrigeration compressor unit is a small GM refrigeration unit, with its cold head and compressor arranged in parallel, used to reduce the system temperature to an operating temperature of 2.3K within a preset time period.

[0037] Compared to traditional liquid helium Dewars that require long pre-cooling times or large refrigerators, the small GM refrigerator can cool the system to operating temperature within hours (e.g., 8 hours), significantly reducing system preparation time and improving efficiency. Furthermore, the parallel arrangement of the cold head and compressor helps reduce the system's horizontal dimensions, which, combined with the vertical layout, achieves an overall compact design.

[0038] In one embodiment, the vacuum level inside the cryogenic thermostat is maintained below 5 Pa, and multiple layers of thermal insulation material are used for shielding to minimize external heat load.

[0039] In this embodiment, by maintaining the vacuum level inside the cryostat below 5 Pa and employing multi-layered thermal insulation material shielding, the high vacuum environment effectively eliminates the heat load caused by gas convection and conduction, while the multi-layered insulation material blocks radiative heat transfer. The combination of these two factors reduces the heat transferred from the external environment to the low-temperature region. This low heat load means the cryostat only needs to withstand less heat to maintain the low temperature, thereby reducing the cryostat's power consumption, improving the system's operational economy, and ensuring the long-term stability of the detector's operating temperature.

[0040] In one embodiment, the electronic control module includes: a precision bias current source for providing a bias close to the critical current of the superconducting single-photon detector array; a low-noise preamplifier for amplifying the weak voltage pulses generated by the detector; and a digital signal processing unit based on FPGA or ASIC for realizing high-speed pulse discrimination and photon counting.

[0041] A precision current source provides a stable bias point for the SNSPD close to its critical current, which is an electrical prerequisite for achieving high detection efficiency and low dark count. A low-noise amplifier effectively amplifies weak voltage pulses in the nanovolt range while introducing extremely low self-noise, ensuring signal quality. FPGAs or ASICs enable high-speed (picosecond-level) pulse discrimination and photon counting, meeting the needs of high count rate applications and directly outputting digital results.

[0042] In one embodiment, the system suppresses noise by using a short-distance shielded cable to connect the electronic control module to the superconducting single-photon detector array and the refrigerator compressor unit; and / or, the detector array is fixed inside the cryostat by a low-vibration mechanical support structure.

[0043] Short-distance shielded cables reduce the antenna effect, effectively preventing external electromagnetic noise from interfering with weak signals, while also reducing signal transmission loss. Mechanical vibrations generated by the operation of chillers, etc., can affect the performance of SNSPDs. Low-vibration support structures can isolate or attenuate vibrations, reducing additional dark counts and timing jitter caused by vibrations, and improving measurement accuracy.

[0044] In one embodiment, the electronic control module adopts a replaceable modular design, allowing for adaptation to different specifications of superconducting single-photon detector chips by replacing the interface units. When the detector chip needs to be replaced or upgraded, the entire electronic control system does not need to be replaced; only the corresponding interface module needs to be replaced, reducing the cost and complexity of system upgrades and maintenance. This makes the system a universal platform adaptable to detectors of different specifications, expanding its application scope.

[0045] In one embodiment, the system's performance in the 1550 nm communication band meets the following requirements: system detection efficiency not less than 70%; dark count rate not more than 100 per second; and time jitter not more than 50 picoseconds.

[0046] The present invention also proposes a superconducting single-photon detection method. Figure 3 This is a flowchart illustrating a superconducting single-photon detection method as provided in an exemplary embodiment. Figure 3 As shown, the method includes the following steps: Step 301: With the superconducting single-photon detector array set in a stable low-temperature region inside a cryostat, the cryostat provides and maintains the vacuum and low-temperature environment required for the operation of the superconducting single-photon detector array. Step 302: Provide cooling capacity through the refrigeration compressor unit, wherein the refrigeration compressor unit is coupled to the low-temperature thermostat through a cold head; Step 303: Provide bias, signal processing and status monitoring for the superconducting single-photon detector array and the cryogenic compressor unit through the electronic control module; wherein, the superconducting single-photon detector array, the cryogenic thermostat, the cryogenic compressor unit and the electronic control module adopt a parallel vertical compact integrated layout, which is compactly integrated in the vertical direction so that the total height of the system does not exceed 0.5 meters and meets the installation specifications of 11U standard rack.

[0047] In this embodiment, on the one hand, the fundamental problem of "large size and difficult deployment" mentioned in the background art is directly solved. Through a compact vertical layout, the total system height is controlled to within 0.5 meters, allowing it to be directly installed in a standard 11U rack, greatly saving space and facilitating rack-mount deployment and integration in space-constrained environments such as laboratories and data centers. On the other hand, the vertical layout facilitates heat dissipation by utilizing the convection principle of naturally rising hot air, improving the system's thermal management efficiency and enhancing long-term operational stability and reliability. Furthermore, the high integration of subsystems such as detectors, cryogenics, cooling, and electrical control reduces external connections and piping, lowering system complexity and failure rate, and improving overall system integrity.

[0048] Figure 4 This is a schematic structural diagram of a device provided in an exemplary embodiment. Please refer to... Figure 4 At the hardware level, the device includes a processor 402, an internal bus 404, a network interface 406, memory 408, and non-volatile memory 410, and may also include other hardware required for its functions. One or more embodiments of the present invention can be implemented in software, for example, the processor 402 reads the corresponding computer program from the non-volatile memory 410 into memory 408 and then runs it. Of course, in addition to software implementation, one or more embodiments of the present invention do not exclude other implementation methods, such as logic devices or a combination of hardware and software, etc. That is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0049] Please refer to Figure 5 An information extraction device for electricity demand forecasting can be applied to, for example... Figure 5 The device shown, in order to implement the technical solution of the present invention, includes: The maintenance unit 501 is used to provide and maintain the vacuum and low temperature environment required for the operation of the superconducting single-photon detector array when the superconducting single-photon detector array is set in a stable low temperature region inside the cryostat. The coupling unit 502 is used to provide cooling capacity through the refrigeration compressor unit, which is coupled to the low-temperature thermostat via a cold head. The processing unit 503 is used to provide bias, signal processing and status monitoring for the superconducting single-photon detector array and the cryo-compressor unit through the electronic control module; wherein the superconducting single-photon detector array, the cryostat, the cryo-compressor unit and the electronic control module adopt a parallel vertical compact integrated layout, which is compactly integrated in the vertical direction so that the total height of the system does not exceed 0.5 meters and meets the installation specifications of 11U standard rack.

[0050] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer, which can take the form of a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email sending and receiving device, game console, tablet computer, wearable device, or any combination of these devices.

[0051] In a typical configuration, a computer includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0052] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0053] Computer-readable media, including both permanent and non-permanent, removable and non-removable media, can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage, quantum memory, graphene-based storage media or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0054] For any other form of computer-readable medium (or computer-readable storage medium) as described above, computer instructions may be stored thereon, which, when executed by a processor, implement one or more of the above embodiments, thereby realizing the technical solution of the present invention.

[0055] The present invention also proposes a computer program that, when executed by a processor, implements one or more of the embodiments described above, thereby realizing the technical solution of the present invention. This computer program may be specifically recorded on the above-described or other computer-readable media, and the present invention does not impose any limitations on this.

[0056] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0057] The foregoing has described specific embodiments of the invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0058] The terminology used in one or more embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in one or more embodiments of the invention and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0059] It should be understood that although the terms first, second, third, etc., may be used to describe various information in one or more embodiments of the present invention, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of one or more embodiments of the present invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0060] The above description is merely a preferred embodiment of one or more embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of the present invention should be included within the protection scope of one or more embodiments of the present invention.

Claims

1. A superconducting single-photon detection system, comprising: The system adopts a parallel vertical compact integrated layout, comprising: a superconducting single-photon detector array arranged in a stable low-temperature zone inside a cryostat; the cryostat is used to provide and maintain a vacuum and low-temperature environment required for the superconducting single-photon detector array to work; a refrigerator compressor unit coupled with the cryostat through a cold head for providing cold energy; an electric control module connected with the superconducting single-photon detector array and the refrigerator compressor unit for providing bias, signal processing and state monitoring; wherein the superconducting single-photon detector array, the cryostat, the refrigerator compressor unit and the electric control module are compactly integrated in the vertical direction, so that the total height of the system does not exceed 0.5 meters, and meets the installation specifications of 11U standard rack.

2. The system of claim 1, wherein, The superconducting single-photon detector array is composed of not less than 16 independent superconducting nanowire single-photon detector chips, the superconducting nanowires on the chip are arranged in a meandering grating shape, the width of the superconducting nanowires is 50-150 nanometers, and the material of the superconducting nanowires includes at least one of the following: NbN, NbTiN, MoSi, WSi.

3. The system of claim 2, wherein, A distributed Bragg reflector structure is integrated below each superconducting single-photon detector chip, the distributed Bragg reflector structure is formed by alternately stacking high-refractive-index layers and low-refractive-index layers to form an optical microcavity for enhancing the absorption efficiency of photons of a specific waveband.

4. The system of claim 3, wherein, The optical microcavity of the distributed Bragg reflector structure is optimized to have high absorption rate for incident light of both TE and TM modes, so as to achieve insensitive response to the polarization state of the incident light, wherein the difference in absorption efficiency between TE and TM modes is less than 5%.

5. The system of claim 1, wherein, The refrigerator compressor unit is a small GM refrigerator, and the cold head and the compressor are arranged in parallel, for reducing the system temperature to a working temperature of 2.3K within a preset time.

6. The system of claim 1, wherein, The internal vacuum degree of the cryostat is maintained below 5Pa, and a multi-layer thermal insulation material is used for shielding to minimize external thermal load.

7. The system of claim 1, wherein, The electric control module comprises: a precision bias current source for providing a bias close to the critical current of the superconducting single-photon detector array; a low-noise preamplifier for amplifying the weak voltage pulses generated by the detector; a digital signal processing unit based on FPGA or ASIC for realizing high-speed pulse discrimination and photon counting.

8. The system of claim 1, wherein, The system suppresses noise in the following ways: The electric control module is connected with the superconducting single-photon detector array and the refrigerator compressor unit through short-distance shielded cables; and / or A low-vibration mechanical support structure is used inside the cryostat to fix the detector array.

9. The system of claim 1, wherein, The electric control module adopts a replaceable modular design, and different specifications of superconducting single-photon detector chips can be adapted by replacing the interface unit.

10. The system of claim 1, wherein, The performance indicators of the system in the 1550nm communication waveband meet the following requirements: The system detection efficiency is not less than 70%; The dark count rate is not higher than 100 per second; The time jitter is not greater than 50 picoseconds.

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