Superconducting single-photon detection structure and preparation method thereof

Abstract

The present invention relates to the field of single-photon detection technology, and provides a superconducting single-photon detection structure and a preparation method thereof. The structure includes: a plurality of detection units, a transmission feeder, a power line, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide; a plurality of detection units are separated by a power line to form a resonator array, and the power line is connected to the ground end of each detection unit; each detection unit includes a serpentine nanowire and an interdigital capacitor; the resonant frequency of the corresponding detection unit is determined according to the length of the interdigital capacitor; the transmission feeder is coupled with each detection unit and is used for frequency domain readout of the resonator array; the first coplanar waveguide is connected to the first end of the power line, the second coplanar waveguide is connected to the second end of the transmission feeder, and the third coplanar waveguide is connected to the first end of the transmission feeder. The present invention increases the resonant frequency range of each resonator, while increasing the resonant frequency of the resonator, simplifies the complexity of the readout circuit, and has strong practicality.

Description

Technical Field

[0001] The present invention relates to the technical field of single photon detection, and in particular to a superconducting single photon detection structure and a preparation method thereof. Background Art

[0002] Light is one of the main carriers of information closely related to human daily life activities. Converting light into electrical signals is crucial to understanding its inherent properties and making better use of it. With the extreme demand for detecting a large number of dim targets, such as distant celestial observations, long-distance laser ranging, and bioluminescence analysis, the limit of light detection has been pushed to the level of a single photon.

[0003] The energy gap of superconductors is in the meV range, which is 3 orders of magnitude lower than that of traditional semiconductor materials, and they work in a deep cryogenic refrigeration environment. Therefore, single-photon detectors based on superconductors have unparalleled advantages in detection sensitivity, signal-to-noise ratio, etc., and have great prospects for scientific and engineering applications. Currently, the most common superconducting single-photon detection technology is based on the principle of micro-energy devices, such as the TES (Transition Edge Sensors) detector of STAR Cryoelectronics in the United States. It mainly achieves ultra-sensitive detection of incident photons by biasing the device on the edge interval of the superconducting critical transition and utilizing the nonlinear temperature-resistance transition relationship of the superconductor in this interval. However, the above-mentioned working principle based on thermal effects makes the detector's response time longer, and the currently used superconducting flux quantum interference readout technology is very complex, which limits its large-array integration and large-scale engineering application prospects.

[0004] At present, etching superconducting thin films into nanowire structures has improved the time resolution capabilities of superconducting single-photon detectors, such as response speed (ns) and time jitter (10ps), to an unprecedented level. However, due to the lack of simple and effective large-array readout technology, it has never been able to be used in large-array imaging applications. A small number of multiplexing technologies based on array nanowires are also relatively complex in terms of chips and circuits, and have high requirements for the wiring design of the detector chip and the cooling capacity of the refrigeration equipment. Summary of the invention

[0005] The embodiment of the present invention provides a superconducting single-photon detection structure and a preparation method thereof.

[0006] A first aspect of an embodiment of the present invention provides a superconducting single-photon detection structure, comprising: a plurality of detection units, a transmission feeder, a power line, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide;

[0007] The plurality of detection units are separated by the power line to form a resonator array, and the power line is connected to the ground terminal of each detection unit;

[0008] Each of the detection units comprises: a nanowire with a serpentine structure and an interdigital capacitor; wherein the resonant frequency of the corresponding detection unit is determined according to the length of the interdigital capacitor;

[0009] The transmission feed line is coupled to each of the detection units and is used for frequency domain readout of the resonator array;

[0010] The first coplanar waveguide is connected to the first end of the power line, and the second end of the power line is grounded; the second coplanar waveguide is connected to the second end of the transmission feeder, and the third coplanar waveguide is connected to the first end of the transmission feeder.

[0011] Furthermore, both ends of the power line are also connected to an external constant current source, so that the current superconducting single-photon detection structure is in a single-photon mode;

[0012] Both ends of the power line are disconnected from the external constant current source, so that the superconducting single-photon detection structure is currently in a photon number resolution mode.

[0013] Furthermore, the materials of the nanowires, the interdigital capacitors, the transmission feed lines, the power lines, the first coplanar waveguides, the second coplanar waveguides and the third coplanar waveguides are any one of niobium nitride, magnesium diboride, niobium, molybdenum silicide, titanium nitride and aluminum.

[0014] Furthermore, the thickness of the nanowire is 5 nm to 5 μm;

[0015] The width of the nanowire is 50nm to 5μm;

[0016] The total length of the nanowires is determined according to the corresponding resonant frequency of the detection unit.

[0017] Furthermore, the width of the interdigital capacitor is a preset multiple of the width of the corresponding nanowire, so that the photosensitive area of ​​the corresponding detection unit is the nanowire.

[0018] Furthermore, the spatial interval between the detection units of adjacent resonant frequencies is not less than a preset distance;

[0019] The preset distance is used to avoid coupling effects between the detection units of adjacent resonant frequencies.

[0020] A second aspect of an embodiment of the present invention provides a method for preparing a superconducting single-photon detection structure, comprising:

[0021] A superconducting thin film is grown on the substrate;

[0022] A plurality of detection units, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide are prepared on the superconducting film; each of the detection units comprises: a nanowire with a serpentine structure and an interdigital capacitor, and the resonant frequency of the corresponding detection unit is determined according to the length of the interdigital capacitor;

[0023] Among them, the multiple detection units are separated by the power line to form a resonator array, and the power line is connected to the ground end of each detection unit; the transmission feeder is coupled to each detection unit; the first coplanar waveguide is connected to the first end of the power line, and the second end of the power line is grounded; the second coplanar waveguide is connected to the second end of the transmission feeder, and the third coplanar waveguide is connected to the first end of the transmission feeder.

[0024] Furthermore, the method of preparing a plurality of detection units, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide on the superconducting film comprises:

[0025] Spin coating a photoresist layer on the superconducting film;

[0026] Arranging a plurality of interdigital capacitors, a transmission feed line, a power line, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide on the superconducting film coated with the photoresist layer;

[0027] removing the photoresist layer;

[0028] A plurality of nanowires with the serpentine structure are prepared on the superconducting film from which the photoresist layer is removed, and the nanowires are connected to the interdigital capacitors in a one-to-one correspondence.

[0029] Furthermore, the method of arranging a plurality of interdigital capacitors, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide on the superconducting film coated with the photoresist layer comprises:

[0030] On the superconducting film coated with the photoresist layer, a plurality of interdigital capacitors, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide are arranged on the superconducting film through photolithography and reactive ion beam etching processes.

[0031] Furthermore, the step of preparing a plurality of nanowires of the serpentine structure on the superconducting film from which the photoresist layer is removed comprises:

[0032] A plurality of nanowires with the serpentine structure are prepared on the superconducting film with the photoresist layer removed by a focused ion beam etching process.

[0033] Compared with the prior art, the superconducting single-photon detection structure and the preparation method thereof of the embodiment of the present invention have the following beneficial effects:

[0034] A superconducting resonator is formed by using serpentine nanowires and interdigital capacitors to form a single detection unit. The nanowire serves as the inductance part of the superconducting resonator. By changing the length of the interdigital capacitor coupled with the nanowire, the resonant frequency of each superconducting resonator (detection unit) can be changed. The coupling of a single microwave transmission feed line and the detection unit realizes the readout of a frequency domain array of multiple resonators, and the readout circuit is simple and easy to process. The multifunctional application of a single device greatly increases the commercial value of the detector. This embodiment has a good prospect for promotion and application, and can be widely used in the field of photoelectric detection, especially in the fields of large array imaging, radar and astronomical observation that require extreme time resolution and energy resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of a superconducting single-photon detection structure provided by an embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of a resonator based on nanowires and interdigital capacitors provided by an embodiment of the present invention being coupled to a transmission feed line and a power line respectively;

[0037] Figure 3 is an equivalent circuit diagram of a superconducting single-photon detection structure provided by an embodiment of the present invention;

[0038] Figure 4 is a schematic diagram of a method for preparing a superconducting single-photon detection structure provided by an embodiment of the present invention;

[0039] Figure 5 yes Figure 4 Schematic diagram of the specific implementation process of step S402;

[0040] Figure 6 It is a schematic diagram of the structure of a substrate-grown superconducting thin film provided by an embodiment of the present invention;

[0041] Figure 7 It is a schematic diagram of the structure of spin coating photoresist on a superconducting thin film provided by an embodiment of the present invention;

[0042] Figure 8 is a schematic diagram of a structure after etching is performed on a photoresist provided by an embodiment of the present invention;

[0043] Fig. 9 is a schematic diagram of a structure after etching is performed on a superconducting thin film provided by an embodiment of the present invention;

[0044] Fig.10 is a schematic structural diagram of a superconducting film with photoresist removed provided by an embodiment of the present invention;

[0045] Fig.11 is a schematic diagram of a superconducting single-photon detection structure provided by an embodiment of the present invention;

[0046] Fig.12 It is a schematic diagram of the structure of the nanowire provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0047] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are provided to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may also be implemented in other embodiments without these specific details.

[0048] In order to illustrate the technical solution of the present invention, a specific embodiment is provided below for illustration.

[0049] See also Figure 1 , is a schematic diagram of a superconducting single-photon detection structure provided in this embodiment. The present invention is applicable to the fields of photoelectric detection, large array imaging, radar, astronomical observation, and is particularly applicable to the extreme detection requirements of dim targets, such as distant celestial body observation, long-distance laser ranging, and bioluminescence analysis. For ease of explanation, only the parts related to this embodiment are shown.

[0050] The superconducting single-photon detection structure mainly includes: a plurality of detection units 8, a transmission feed line 5, a power line 4, a first coplanar waveguide 1, a second coplanar waveguide 2 and a third coplanar waveguide 3.

[0051] In the prior art, there is a technology that etches superconducting thin films into nanowire structures, which improves the time resolution capabilities of the detector, such as the response speed and time jitter, to an unprecedented level. However, due to the lack of simple and effective large-array readout technology, it has never been able to be used in large-array imaging applications. In addition, a small number of multiplexing technologies based on array nanowires are also relatively complex in terms of chips and circuits. For example, transmission delay lines and single-flux quantum logic circuits require multiple coaxial cables, which places high demands on the wiring design of the detector chip and the cooling capacity of the cooling equipment.

[0052] Therefore, this embodiment proposes a superconducting single-photon detector for high-precision pulsar angular position measurement. In response to the extremely weak pulsar signal flow and ultra-short coherence time, the detector of this embodiment has extreme time resolution and large-array integration capabilities.

[0053] Specifically, Figure 1 , a plurality of detection units 8 are separated by power lines 4 to form a resonator array, and the power lines 4 are connected to the ground end of each detection unit 8. Each detection unit 8 can be used as a superconducting resonator.

[0054] Each detection unit 8 includes: a serpentine nanowire 7 and an interdigital capacitor 6, wherein the resonant frequency of the corresponding detection unit 8 is determined according to the length of the interdigital capacitor 6. Figure 2 , which is a schematic diagram of a resonator based on a nanowire 7 and an interdigital capacitor 6 provided in an embodiment coupled with a transmission feed line 5 and a power line 4 respectively.

[0055] See also Figure 3 , is an equivalent circuit diagram of the superconducting single-photon detection structure of this embodiment, each detection unit 8 includes an inductor L1 and a capacitor C1, and the serpentine nanowire 7 can be used as the inductor part of the corresponding detection unit 8, such as Figure 3 The inductor L1 and the interdigital capacitor 6 are as follows: Figure 3 The capacitor C1 in.

[0056] In the circuit of the superconducting material of this embodiment, the resonant frequency is:

[0057]

[0058] Among them, L m is the magnetic inductance of the resonant cavity, L k is the dynamic inductance, and C is the coupling capacitance. Since the dynamic inductance L in the superconducting resonator k is the magnetic inductance L m The inductance is several dozen times greater than that of the conventional superconducting resonant circuit, so the inductance is mainly contributed by the dynamic inductance. The nanowire 7 has a very small cross-sectional area and has a larger dynamic inductance than the conventional superconducting resonant circuit. Therefore, the structure of this embodiment can increase the resonant frequency of the resonator while maintaining a relatively short length of the nanowire 7.

[0059] The transmission feeder 5 is coupled to each detection unit 8. The transmission feeder 5 is used for frequency domain readout of the resonator array. In this embodiment, the readout and position resolution of the resonator array can be realized through a transmission feeder 5, which greatly simplifies the complexity of the readout circuit and has greater practicality and engineering application value.

[0060] The first coplanar waveguide 1 is connected to the first end of the power line 4, and the second end of the power line 4 is grounded. The second coplanar waveguide 2 is connected to the second end of the transmission feeder 5, and the third coplanar waveguide 3 is connected to the first end of the transmission feeder 5. In this embodiment, the coplanar waveguide structures on both sides are mainly used to transmit and read out high-frequency signals, and sufficient bonding space can be reserved.

[0061] The above detection structure adopts a serpentine nanowire 7 and an interdigital capacitor 6 to form a superconducting resonator to form a single detection unit 8. The nanowire 7 serves as the inductance part of the superconducting resonator. By changing the length of the interdigital capacitor 6 coupled thereto, the resonant frequency of each superconducting resonator (detection unit 8) can be changed. The coupling of a single microwave transmission feed line 5 and the detection unit 8 realizes the readout of the frequency domain array of multiple resonators, and the readout circuit is simple and easy to process. The multifunctional application of a single device greatly increases the commercial value of the detector. This embodiment has a good prospect for promotion and application, and can be widely used in the field of photoelectric detection, especially in the fields of large array imaging, radar and astronomical observation that require extreme time resolution and energy resolution.

[0062] Furthermore, both ends of the power line 4 of this embodiment are also connected to an external constant current source, so that the current superconducting single-photon detection structure is in a single-photon mode.

[0063] When both ends of the power line 4 are disconnected from the external constant current source, the current superconducting single-photon detection structure can be placed in a photon number resolution mode.

[0064] This embodiment changes the current bias mode so that the superconducting single-photon detector can work in the photon number resolution mode or the single-photon counting mode. Specifically, the power line 4 is disconnected from the external constant current source, and the photon incidence will linearly change the dynamic inductance of the nanowire 7. The detector works in the linear range, thereby modulating the resonant frequency, and reading out in the frequency domain through a transmission feeder 5, which can achieve photon energy and photon number resolution. The power line 4 is connected to an external constant current source to enable the detector to work in the nonlinear region, and the time domain waveform of the acquisition device (such as an oscilloscope) can achieve fast response, ultra-low time jitter, ultra-high time resolution single photon detection, and further perform Fourier transformation to achieve photon position resolution.

[0065] The above dual working modes enable the detector structure to have spatial resolution capability, and by changing the current bias mode, the nanowire 7 can switch between nonlinear and linear working ranges, which can meet the application requirements of ultra-high time resolution and photon number resolution respectively, greatly increasing the commercial value of the detector.

[0066] Furthermore, the materials of the nanowire 7, the interdigital capacitor 6, the transmission feed line 5, the power line 4, the first coplanar waveguide 1, the second coplanar waveguide 2 and the third coplanar waveguide 3 are any one of niobium nitride (NbN), magnesium diboride (MgB2), niobium (Nb), molybdenum silicide (MoSi), titanium nitride (TiN) and aluminum (Al).

[0067] It should be understood that the present embodiment does not specifically limit the specific materials of the nanowire 7, interdigital capacitor 6, transmission feed line 5, power line 4, first coplanar waveguide 1, second coplanar waveguide 2 and third coplanar waveguide 3. The nanowire 7, interdigital capacitor 6, transmission feed line 5, power line 4, first coplanar waveguide 1, second coplanar waveguide 2 and third coplanar waveguide 3 can be made of the same superconducting material, and different parts can also be made of different superconducting materials.

[0068] Furthermore, the thickness of the nanowire 7 is 5 nm to 5 μm, the width of the nanowire 7 is 50 nm to 5 μm, and the duty ratio of the nanowire 7 can be about 1: 1. The line width of hundreds of nanometers can increase the number of resonant cavities that can be integrated within the same detection area, thereby increasing the resonant frequency, and a higher resonant frequency is conducive to increasing the resonant frequency range of each resonator.

[0069] Optionally, the total length of the nanowire 7 is determined according to the resonance frequency of the corresponding detection unit 8 .

[0070] Optionally, the width of the interdigital capacitor 6 is a preset multiple of the width of the corresponding nanowire 7, so that the photosensitive area of ​​the corresponding detection unit 8 is the nanowire 7. Exemplarily, the width of the interdigital capacitor 6 is 20 times that of the nanowire 7 to ensure that the photosensitive area of ​​each superconducting resonator (detection unit 8) is only the nanowire 7 portion.

[0071] Furthermore, the spatial interval between the detection units 8 of adjacent resonant frequencies is not less than a preset distance; the preset distance is used to avoid the coupling effect between the detection units 8 of adjacent resonant frequencies.

[0072] In practical applications, the width of the transmission feed line 5 and the distance between the detection unit 8 need to be precisely designed to achieve a balance between the coupling strength and the effective area. In addition, in terms of spatial position, the superconducting resonators (detection units 8) of adjacent resonant frequencies need to be as far away as possible to eliminate the coupling effect between the superconducting resonators, such as Figure 1 As shown in FIG. , the resonant frequency of each detection unit 8 can be arranged as follows: Figure 1 As shown, for example, the frequency F1 is close to the frequency F2, but the detection unit 8 with the frequency F1 should be far away from the detection unit 8 with the frequency F2; the frequency F6 is close to the frequency F7, but the detection unit 8 with the frequency F6 should be far away from the detection unit 8 with the frequency F7.

[0073] For example, according to Figure 1 The working mode of the superconducting single photon detection structure of this embodiment is described as follows:

[0074] The end ports of the structures of the first coplanar waveguide 1, the second coplanar waveguide 2 and the third coplanar waveguide 3 are all bonded with lead-out electrodes, and the detector can work in the photon number resolution mode or the single photon counting mode respectively. When working in the photon number resolution mode, disconnect the power line 4 at the constant current source end, connect the ports of the first coplanar waveguide 1 and the second coplanar waveguide 2 to the vector network analyzer respectively, and the photon incidence will linearly change the dynamic inductance of the nanowire 7, thereby modulating the resonant frequency, and read out in the frequency domain through a single transmission feeder 5 combined with a room temperature low noise amplifier, so as to achieve photon energy and photon number resolution. Disconnect the port of the first coplanar waveguide 1, connect the first coplanar waveguide 1 and the constant current source, and the detector can work in the nonlinear single photon counting mode. The time domain waveform of the device can be collected by an oscilloscope to achieve fast response, ultra-low time jitter and ultra-high time resolution single photon detection, and further perform Fourier transform to achieve photon position resolution.

[0075] The above-mentioned superconducting single-photon detection structure adopts a serpentine-structured nanowire 7 and an interdigital capacitor 6 to form a superconducting resonator to form a single detection unit 8. The nanowire 7 serves as the inductance part of the superconducting resonator. By changing the length of the interdigital capacitor 6 coupled thereto, the resonant frequency of each superconducting resonator can be changed. The coupling of a single microwave transmission feed line 5 and the detection unit 8 realizes the readout of the frequency domain array of multiple resonators, and the readout circuit is simple and easy to process. The multifunctional application of a single device greatly increases the commercial value of the detector.

[0076] Corresponding to the superconducting single-photon detection structure described in the above embodiment, this embodiment provides a method for preparing a superconducting single-photon detection structure. Figure 4 , is a flow chart of an embodiment of a method for preparing a superconducting single-photon detection structure in this embodiment. The details are as follows:

[0077] Step S401 : growing a superconducting thin film 102 on the substrate 101 .

[0078] See also Figure 6 , which is a schematic diagram of growing a superconducting thin film 102 on a substrate 101.

[0079] Optionally, the thickness of the superconducting film 102 in this embodiment may be 5 nm to 5 μm.

[0080] Step S402, preparing multiple detection units, transmission feed lines, power lines, first coplanar waveguides, second coplanar waveguides and third coplanar waveguides on the superconducting film 102; each of the detection units includes: a serpentine structure of nanowires and interdigital capacitors, and the resonant frequency of the corresponding detection unit is determined according to the length of the interdigital capacitors.

[0081] Among them, the multiple detection units are separated by the power line to form a resonator array, and the power line is connected to the ground end of each detection unit; the transmission feeder is coupled to each detection unit; the first coplanar waveguide is connected to the first end of the power line, and the second end of the power line is grounded; the second coplanar waveguide is connected to the second end of the transmission feeder, and the third coplanar waveguide is connected to the first end of the transmission feeder.

[0082] Further, see Figure 5 The specific implementation process of preparing a plurality of detection units, transmission feed lines, power lines, first coplanar waveguides, second coplanar waveguides and third coplanar waveguides on the superconducting film 102 in step S402 may include:

[0083] Step S501 , spin coating a photoresist layer 103 on the superconducting film 102 .

[0084] See also Figure 7 , which is a schematic diagram of spin coating a photoresist layer 103 on the superconducting film 102.

[0085] Step S502 , arranging a plurality of interdigital capacitors, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide on the superconducting film 102 coated with the photoresist layer 103 .

[0086] See also Figure 8 First, a plurality of interdigital capacitors, transmission feed lines, power lines, first coplanar waveguides, second coplanar waveguides and third coplanar waveguides are patterned on the photoresist layer 103. Fig. 9 A plurality of interdigital capacitors, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide are arranged on the superconducting film 102, that is, the plurality of interdigital capacitors, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide are moved onto the superconducting film 102.

[0087] Step S503 , removing the photoresist layer 103 .

[0088] See also Fig.10 , is a schematic diagram of removing the photoresist layer 103 above the superconducting film 102.

[0089] Step S504 , preparing a plurality of nanowires with the serpentine structure on the superconducting film 102 with the photoresist layer 103 removed, wherein the nanowires are connected to the interdigital capacitors in a one-to-one correspondence.

[0090] See also Fig.11 , which is a schematic diagram of the preparation of a superconducting single-photon detection structure.

[0091] Furthermore, the specific implementation process of providing a plurality of interdigital capacitors, transmission feed lines, power lines, first coplanar waveguides, second coplanar waveguides and third coplanar waveguides on the superconducting film 102 coated with the photoresist layer 103 in step S502 includes:

[0092] On the superconducting film 102 coated with the photoresist layer 103, a plurality of interdigital capacitors, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide are arranged on the superconducting film 102 by photolithography and reactive ion beam etching.

[0093] See also Figure 8 First, a plurality of interdigital capacitors, transmission feed lines, power lines, first coplanar waveguides, second coplanar waveguides and third coplanar waveguides are patterned on the photoresist layer 103 using a photolithography process, see Fig. 9 , and then a plurality of interdigital capacitors, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide are arranged on the superconducting film 102 by using a reactive ion beam etching process.

[0094] Furthermore, the step S504 of preparing a plurality of nanowires of the serpentine structure on the superconducting film 102 from which the photoresist layer 103 is removed comprises:

[0095] On the superconducting film 102 from which the photoresist layer 103 is removed, a plurality of nanowires of the serpentine structure are prepared by a focused ion beam etching process.

[0096] Optionally, this embodiment may also adopt a multi-step electron beam exposure process to form the nanowire structure.

[0097] In this embodiment, the preparation method of the nanowire adopts a single-step focused ion beam etching process. Compared with the traditional multi-step processes such as coating PMMA (PolyMethylMethAcrylate) glue, pre-baking, electron beam lithography (E-BeamLithography, EBL), development, reactive ion beam etching and degumming, the preparation of the nanowire can be completed by only a one-step focused ion beam etching process, which not only reduces the preparation cost but also improves the success rate of the preparation. Moreover, this process is particularly suitable for the preparation of unstable superconducting thin films 102, such as MgB2 thin films, which are easily deliquescent when exposed to water and cannot be prepared for nanowires using an electron beam exposure process.

[0098] Exemplarily, in this embodiment, a superconducting film 102 of a preset thickness can be grown on a substrate 101 by magnetron sputtering or a hybrid physical and chemical vapor deposition method; then a photoresist 103 is spin-coated on the superconducting film 102; peripheral structures such as interdigital capacitors, transmission feed lines, power lines, and coplanar waveguides are transferred to the superconducting film 102 by photolithography and reactive ion beam etching methods in sequence; finally, a focused ion beam process is used to directly etch out the meandering nanowire portion in the resonator, such as Fig.12 , is an electron microscope photograph of the nanowire structure obtained by direct etching on the MgB2 film using the focused ion beam process.

[0099] The preparation method of the above-mentioned superconducting single-photon detection structure is to arrange multiple interdigital capacitors, transmission feed lines, power lines, first coplanar waveguides, second coplanar waveguides and third coplanar waveguides on the superconducting film 102 coated with a photoresist layer 103 in sequence through photolithography and reactive ion beam etching processes, and then use a single-step focused ion beam etching process to complete the preparation of nanowires, thereby reducing the preparation cost and improving the success rate of preparation; at the same time, the coupling of a single microwave transmission feed line and the detection unit realizes the readout of the frequency domain array of the multi-resonator, and the readout circuit is simple and easy to process, which greatly increases the commercial value of the detector.

[0100] Those skilled in the art will appreciate that the sequence numbers of the steps in the above embodiments do not imply a sequence of execution, and the execution sequence of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0101] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A superconducting single-photon detection structure, characterized in that: include: A plurality of detection units, a transmission feed line, a power line, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide; The plurality of detection units are separated by the power line to form a resonator array, and the power line is connected to the ground terminal of each detection unit; Each of the detection units comprises: a nanowire with a serpentine structure and an interdigital capacitor; wherein the resonant frequency of the corresponding detection unit is determined according to the length of the interdigital capacitor; The transmission feed line is coupled to each of the detection units and is used for frequency domain readout of the resonator array; The first coplanar waveguide is connected to the first end of the power line, and the second end of the power line is grounded; the second coplanar waveguide is connected to the second end of the transmission feeder, and the third coplanar waveguide is connected to the first end of the transmission feeder; The two ends of the power line are also connected to an external constant current source, so that the current superconducting single-photon detection structure is in a single-photon mode; the two ends of the power line are disconnected from the external constant current source, so that the current superconducting single-photon detection structure is in a photon number resolution mode; The thickness of the nanowire is 5nm~5µm; the width of the nanowire is 50nm~5µm; the total length of the nanowire is determined according to the resonance frequency of the corresponding detection unit; The width of the interdigital capacitor is a preset multiple of the width of the corresponding nanowire, so that the photosensitive area of ​​the corresponding detection unit is the nanowire; The spatial interval between the detection units of adjacent resonant frequencies is not less than a preset distance; the preset distance is used to avoid coupling effects between the detection units of adjacent resonant frequencies.

2. The superconducting single-photon detection structure according to claim 1, characterized in that: The materials of the nanowire, the interdigital capacitor, the transmission feed line, the power line, the first coplanar waveguide, the second coplanar waveguide and the third coplanar waveguide are any one of niobium nitride, magnesium diboride, niobium, molybdenum silicide, titanium nitride and aluminum.

3. A method for preparing a superconducting single-photon detection structure, characterized in that: include: A superconducting thin film is grown on the substrate; A plurality of detection units, transmission feed lines, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide are prepared on the superconducting film; each of the detection units comprises: a nanowire with a serpentine structure and an interdigital capacitor, and the resonant frequency of the corresponding detection unit is determined according to the length of the interdigital capacitor; Wherein, the multiple detection units are separated by the power line to form a resonator array, and the power line is connected to the ground end of each detection unit; the transmission feeder is coupled to each detection unit; the first coplanar waveguide is connected to the first end of the power line, and the second end of the power line is grounded; the second coplanar waveguide is connected to the second end of the transmission feeder, and the third coplanar waveguide is connected to the first end of the transmission feeder; The method comprises: spin coating a photoresist layer on the superconducting film; arranging a plurality of interdigital capacitors, transmission feeders, power lines, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide on the superconducting film coated with the photoresist layer; removing the photoresist layer; and preparing a plurality of nanowires of the serpentine structure on the superconducting film from which the photoresist layer is removed, wherein the nanowires are connected to the interdigital capacitors in a one-to-one correspondence. The method of arranging a plurality of interdigital capacitors, a transmission feed line, a power line, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide on a superconducting film coated with the photoresist layer comprises: arranging a plurality of interdigital capacitors, a transmission feed line, a power line, a first coplanar waveguide, a second coplanar waveguide and a third coplanar waveguide on the superconducting film coated with the photoresist layer by sequentially using a photolithography process and a reactive ion beam etching process.

4. The method for preparing a superconducting single-photon detection structure according to claim 3, characterized in that: The step of preparing a plurality of nanowires of the serpentine structure on the superconducting thin film from which the photoresist layer has been removed comprises: A plurality of nanowires with the serpentine structure are prepared on the superconducting film with the photoresist layer removed by a focused ion beam etching process.

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