Superconducting nanowire single-photon detector and detection device

Abstract

The invention provides a superconducting nanowire single-photon detector and detection device, and the detector comprises a plurality of detection units which are arranged in a winding manner and are cascaded in sequence, and each detection unit comprises at least two superconducting nanowires which are connected in parallel; wherein the adjacent corners are distributed in a staggered mode in the width direction of the superconducting nanowires, and the size of each corner in the width direction of the superconducting nanowires is larger than the distance between the adjacent superconducting nanowires in the detection unit. The invention aims to relieve the current crowding effect of the parallel nanowire superconducting single-photon detector, expands the corner design space through staggered placement, decouples the curvature radius of the corner in the detection unit from the filling rate, and achieves the purposes of relieving the current crowding effect under the high filling rate and improving the system detection efficiency. The design structure is simple, and the optimization effect is remarkable; meanwhile, an additional preparation process does not need to be introduced, the thin film is not damaged, and the process robustness is high; in addition, the occupied on-chip area is small, and integrated design is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of superconducting technology, and in particular to a superconducting nanowire single-photon detector and a detection device. Background Art

[0002] Modern photonics applications (from quantum information processing to weak light detection) place dual requirements on single-photon detectors: high count rate (CR) and system detection efficiency (SDE) close to 100%. For example, the secure key rate in quantum key distribution is highly dependent on the efficiency and count rate of the detector; similarly, deep space optical communications also require high-efficiency, high-count rate detectors to achieve ultra-long-distance high-speed signal transmission. Although single-photon avalanche diodes (SPADs) have shown practical value due to their advantages such as room temperature operation and high photon flux, their detection efficiency (<80%) is always limited by the intrinsic properties of semiconductor materials. Although superconducting transition edge sensors (TESs) can achieve excellent detection efficiency, their ultra-long dead time in the microsecond range hinders their practical application. Superconducting nanowire single-photon detectors (SNSPDs) have achieved SDE > 98% with a single detector and count rate > 1 GHz with an array, setting a benchmark for photon counting performance. However, a single SNSPD has not yet been able to achieve both high SDE (> 90%) and high CR (> 10 MHz) at the same time, which requires coordinated optimization of light absorption, quantum efficiency, and recovery time.

[0003] The key to shortening the recovery time of the detector is to reduce its dynamic inductance. Since the dynamic inductance is directly related to the length of the nanowire, the most direct method is to shorten the nanowire by reducing the effective area or reducing the filling factor. However, when considering the light absorption efficiency, both methods are not practical - the arrangement of nanowires will significantly affect the absorption of photons. Experimental studies have shown that well-designed devices must meet two criteria: the effective area diameter ≥ 20μm and the filling factor ≥ 50%. Any failure to meet the standard will cause a sharp drop in light absorption, and this solution at the expense of detection efficiency is unacceptable. There are two feasible solutions: SNSPD array and superconducting nanowire avalanched photodetector (SNAP). SNSPD arrays usually adopt a multi-pixel independent structure. Compared with the single-pixel SNSPD of the same area, the length of each nanowire is greatly shortened, and the dynamic inductance is lower, thereby achieving faster response. However, SNSPD arrays may have thermal crosstalk between adjacent nanowires and usually require more complex readout circuits. SNAP reconstructs nanowires by parallel connection, using the internal avalanche mechanism to reduce inductance and amplify the light response signal. Compared with the SNSPD array, SNAP avoids problems such as thermal crosstalk and complex readout circuits, and has the advantages of simpler process and more intuitive performance characterization.

[0004] Key Performance Indicators - Quantum Efficiency (QE) and I sw / I dep Strong correlation (I sw is the switching current, I dep is the pair removal current). Higher I sw Usually, it can improve QE, but the traditionally designed SNAP often shows low QE at high filling rate, which is manifested by the lack of obvious saturation platform in the detection efficiency curve. This limitation is due to the unexpected I sw Suppression: As the filling rate increases, its current crowding effect is more serious than that of the standard SNSPD. The current crowding effect occurs at the bends of the nanowires. The smaller the wire spacing or the sharper the shape of the inner boundary of the bend, the more significant the effect. The parallel structure of SNAP multiplies the impact of this effect. Therefore, a suitable optimization method is urgently needed to break through the switching current limitation of high-filling-rate SNAPs to obtain higher QE. Existing solutions are divided into two categories: three-dimensional optimization and two-dimensional optimization: although the three-dimensional method can achieve efficiency improvements that are independent of the filling rate, it requires additional process steps and may even permanently damage the detector surface; the two-dimensional method is more widely used due to its simple operation, but the effect varies with the wiring design.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a superconducting nanowire single-photon detector and a detection device, which are used to solve the problems of corner optimization structure, complex process and the like in the prior art.

[0007] In order to achieve the above-mentioned object and other related objects, the present invention provides a superconducting nanowire single-photon detector, wherein the superconducting single-photon detector comprises: A plurality of detection units cascaded in sequence and arranged in a winding manner, each detection unit comprising at least two superconducting nanowires connected in parallel; Wherein, adjacent corners are staggered in the width direction of the superconducting nanowire, and the size of each corner in the width direction of the superconducting nanowire is larger than the spacing between adjacent superconducting nanowires in the detection unit.

[0008] Optionally, the corners on the connecting sides of adjacent detection units are arranged in a staggered manner from the inside to the outside in a direction away from the center line between the adjacent detection units; and the corresponding level corners in the adjacent detection units are aligned in the width direction.

[0009] More optionally, a spacing between corresponding level corners at the connection sides of adjacent detection units in the width direction is greater than the line width of the superconducting nanowire.

[0010] More optionally, the lengths of the superconducting nanowires in the same detection unit are equal.

[0011] More optionally, the corners between adjacent superconducting nanowires in each detection unit are convex toward a side away from the longer superconducting nanowire.

[0012] More optionally, a dimension of each corner in a width direction of the superconducting nanowire is larger than the width of the superconducting nanowire.

[0013] More optionally, the number of superconducting nanowires connected in parallel in each detection unit is equal, and the number of superconducting nanowires connected in parallel is set to 2-10; each superconducting nanowire includes 1-5 stacked superconducting nanomaterial layers, and when the number of superconducting nanomaterial layers is greater than or equal to 2, an electrical isolation layer is also set between each superconducting nanomaterial layer.

[0014] More optionally, the detection units are arranged in parallel, and the detection units are arranged in sequence in the width direction of the superconducting nanowire.

[0015] More optionally, each detection unit is prepared on a substrate having a reflective mirror.

[0016] In order to achieve the above-mentioned object and other related objects, the present invention provides a detection device, which at least includes the above-mentioned superconducting nanowire single-photon detector.

[0017] As described above, the superconducting nanowire single-photon detector and detection device of the present invention have the following beneficial effects: 1. In the superconducting nanowire single-photon detector and detection device of the present invention, the corners are staggered, and the spacing between the superconducting nanowires can be smaller than the size of the corners in the width direction of the superconducting nanowires. Therefore, the superconducting nanowires can be arranged more densely, thereby improving the filling rate.

[0018] 2. The superconducting nanowire single-photon detector and detection device of the present invention can effectively alleviate the current crowding effect in high-filling-rate superconducting nanowire single-photon detectors by only simple layout modification without damaging the film, expanding the area, or increasing the process steps.

[0019] 3. The present invention is applicable to the design of all parallel superconducting nanowire single-photon detectors and detection devices. It has the advantages of simple design, simple process, easy integrated design, and significant optimization effect. It can be applied to the design of superconducting single-photon detectors in the fields of quantum information, lidar, deep space communication, etc., and assist in related scientific and technological research.

[0020] 4. The superconducting nanowire single-photon detector of the present invention is specifically optimized for the switching current bottleneck of high-filling-rate SNAP. As an example, the systematic characterization of a 2-SNAP device with a filling rate of 50% shows that the design increases the switching current by about 11.5%, enhances the weak saturation detection at 1064nm wavelength to a saturation detection with a switching current interval length of about 11%, and reduces the time jitter FWHM from 60ps to 35ps, with performance that comprehensively surpasses traditional structures. The optimized 2-SNAP in the 1064nm band prepared on a distributed Bragg reflector (DBR) substrate exhibits an excellent system detection efficiency of 96.6% while having a dark count of only 20~30c.ps. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram showing the design principle of a corner inner boundary shape.

[0022] Figure 2 Shown is a schematic diagram of the structure of a superconducting single-photon detector with two nanowires connected in parallel with their corners aligned.

[0023] Figure 3 Display as Figure 2 A partial enlarged schematic diagram of the aligned corner superconducting single-photon detector.

[0024] Figure 4 Shown is a schematic diagram of the current density distribution of the aligned corner obtained by finite element analysis.

[0025] Figure 5 Shown is a schematic structural diagram of the superconducting nanowire single-photon detector of the present invention (taking two nanowires connected in parallel as an example).

[0026] Figure 6 Shown is a partially enlarged schematic diagram of the superconducting nanowire single-photon detector of the present invention.

[0027] Figure 7 Shown is a schematic diagram of current density distribution of the present invention obtained by finite element analysis.

[0028] Figure 8 Shown are transition current statistics and Gaussian fitting curve diagrams of a superconducting single-photon detector with aligned corners and a superconducting nanowire single-photon detector of the present invention.

[0029] Fig. 9 Shown is a comparison chart of the normalized efficiencies of a corner-aligned superconducting single-photon detector and a superconducting nanowire single-photon detector of the present invention at 1064 nm.

[0030] Fig.10 Shown is a comparison of time-correlated single photon counts at 1064 nm between a corner-aligned superconducting single photon detector and a superconducting nanowire single photon detector of the present invention.

[0031] Fig.11 Shown is a comparison chart of the normalized efficiencies of a corner-aligned superconducting single-photon detector and a superconducting nanowire single-photon detector of the present invention at 1550 nm.

[0032] Fig.12 Shown is a comparison of time-correlated single photon counts at 1550 nm between a corner-aligned superconducting single photon detector and a superconducting nanowire single photon detector of the present invention.

[0033] Fig.13 It shows the system detection efficiency and dark count of the distributed Bragg reflector substrate superconducting nanowire single-photon detector of the present invention at 1064nm.

[0034] Component number description 1-corner-aligned superconducting single-photon detector; 2-superconducting nanowire single-photon detector; 21-detection unit; 2a-superconducting nanowire. DETAILED DESCRIPTION

[0035] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] See also Figure 1-Figure 13 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0037] First of all, it should be clear that in order to avoid the current crowding effect, the literature "Clem, JR&Berggren, KK Geometry-dependent critical currents in superconducting nanocircuits. Physical Review B 84, 174510 (2011)” has given an optimal corner inner boundary curve design, and the corresponding equation is determined by the following method. This method first regards the nanowire spacing as 0, the line width as a, takes the vertex of the inner boundary of the turn as the origin, and establishes a rectangular coordinate system, such as Figure 1 As shown, then take the origin as the center, take a square with a length and width of 2a, simulate all the current density distribution in the square, and then find that when the inner boundary of the corner satisfies the following optimal curve shape formula (1), we get Figure 1 The inner boundary shape shown by the middle dotted line can maximize the line fill rate while avoiding current crowding.

[0038] x\left ( {y} \right )=\left ( {{a / {π}}} \right )ln\left [ {2\cos {\left ( {{πy / a}} \right )}} \right ] (1) This formula limits the line width of the actual device to half of the initially set a, and further derives that the spacing should be equal to twice the line width. Therefore, the optimal curve design limits the maximum fill rate to 33%. However, a low fill rate means a low light absorption rate, which limits the system detection efficiency of the device. Therefore, detectors designed strictly according to the above method are basically not practical. In actual design, in order to obtain the highest possible detection efficiency, the fill rate of the detection line should be at least 50%.

[0039] Figure 2 A design of a parallel nanowire superconducting single-photon detector taking light absorption rate into consideration is proposed. In this design, the nanowires are folded in a winding manner according to a certain period to form a photon detection area. Two adjacent parallel wires are connected by a 180-degree corner. The corners on the same side are aligned in the vertical direction (the width direction of the nanowire), and the size of the corner in the width direction of the nanowire is equal to the spacing between the nanowires. Figure 3 for Figure 2 A local enlarged schematic diagram shows that the specific nanowire width W1 is 80nm, the spacing S1 between the parallel wires inside the detection unit is 40nm, the spacing S2 between two adjacent detection units is 120nm, and the overall filling rate of the device is 50%. Figure 4 Based on Figure 3 The simulation results of the aligned corner current density with parameter design show that there is a high current density area at the inner boundary of the aligned corner. The ratio of the current density in this area to the straight section is as high as 1.7, and the current crowding effect is obvious.

[0040] In order to solve the above problems, the present invention provides a superconducting nanowire single-photon detector with staggered corners, and explains in detail below how to design the staggered structure, gives specific design parameters for reference, and comprehensively demonstrates the effectiveness and superiority of the present invention in optimizing various aspects of detector performance through simulation comparison of static current density of aligned and staggered corners, statistical comparison of switching currents of multiple aligned corner detectors and multiple staggered corner detectors, and comparison of comprehensive detection performance of a single aligned corner detector and a single staggered corner detector.

[0041] like Figure 5 As shown, the superconducting nanowire single-photon detector 2 of the present invention comprises: A plurality of detection units 21 are arranged in a winding manner and are cascaded in sequence, and each detection unit 21 includes two superconducting nanowires 2a connected in parallel. Adjacent corners are staggered in the width direction of the superconducting nanowires 2a (i.e., not aligned in the width direction), and the size of each corner in the width direction of the superconducting nanowires 2a is greater than the spacing between adjacent superconducting nanowires 2a in the detection unit 21.

[0042] like Figure 5 As shown, in this embodiment, the number of detection units 21 is set to 7. In actual use, the number of detection units 21 is set according to the test needs, and is not limited to this embodiment. As an example, the detection units 21 are arranged in parallel and arranged in sequence in the width direction of the superconducting nanowire 2a. The currents flowing through the two adjacent detection units 21 in the width direction of the superconducting nanowire 2a are in opposite directions, that is, each corner is 180°; the left or right sides of the adjacent detection units 21 are connected together, and the two sides are alternately electrically connected in sequence, thereby realizing cascade (series connection).

[0043] Furthermore, the detection units arranged in sequence in the width direction of the superconducting nanowire 2a are regarded as a group. The detection unit group of the present invention can be set as one group, two groups or more than two groups. Each group of detection unit groups is arranged in sequence in the length direction of the superconducting nanowire 2a, which will not be described one by one here.

[0044] It should be noted that, in actual use, the length direction and arrangement direction of each detection unit can be set according to actual needs (each corner is not necessarily 180°), and is not limited to this embodiment.

[0045] like Figure 5 As shown, the superconducting nanowires 2a in the detection unit 21 are arranged in parallel, and the number of parallel superconducting nanowires 2a is not less than 2; as an example, the number of parallel superconducting nanowires is set to 2-10, which is set according to actual needs (it can also be greater than 10), and is not limited to this embodiment.

[0046] Specifically, in this embodiment, each detection unit 21 includes two superconducting nanowires, each superconducting nanowire 2a is arranged in parallel; the first ends of each superconducting nanowire 2a are connected together, and the second ends are connected together to form a parallel structure. Each superconducting nanowire is a single layer of superconducting nanomaterial layer; it can also be 2 or more layers of superconducting nanomaterial layers (for example, 5 layers, 6 layers), in which case, an electrical isolation layer is also arranged between each superconducting nanomaterial layer (the superconducting nanomaterial layer and the electrical isolation layer are alternately stacked in sequence).

[0047] Specifically, as an example, each corner on the connection side of adjacent detection units 21 is staggered from the inside to the outside in a direction away from the center line between adjacent detection units; and the corresponding level corners in adjacent detection units are aligned in the width direction (in this embodiment, the width direction of the superconducting nanowire is defined, the closer the corner is to the center line between adjacent detection units, the lower the level; the lower the level of the corner is, the closer it is to the inside, and the higher the level is, the closer it is to the outside); that is, the corners on the same side of the same detection unit are staggered from the inside to the outside in increasing order of the corner level. Take the 2nd level corner as an example, if Figure 5As shown, the left ends of the first detection unit and the second detection unit are connected together, the first detection unit and the second detection unit both include 2 levels of corners, and the first level corner in the middle is shared, the second level corner is offset outward relative to the first level corner (the first level corner and the second level corner are not aligned in the width direction of the superconducting nanowire), and the second level corner of the first detection unit is aligned with the second level corner of the second detection unit in the width direction of the super-large nanowire; similarly, the corners of the connection side of the two adjacent detection units at the subsequent stage are set in this way, and no further description is given. Preferably, the lengths of the superconducting nanowires 2a in the same detection unit 21 are equal to ensure the best optimization effect. Preferably, the corresponding level corners on the same side in different detection units are aligned in the width direction of the ultra-large nanowire; it should be noted that, in theory, the spacing in the width direction of the corresponding level corners on the connection side of adjacent detection units (for example, the second level corner on the connection side of the first detection unit and the second detection unit) is larger than the width of the superconducting nanowire (to ensure the normal operation of the avalanche mechanism inside the detector). In actual use, considering the influence of manufacturing precision, it is safer to have the spacing in the width direction of the corresponding level corners on the connection side of adjacent detection units be more than 10nm larger than the width of the superconducting nanowire, while not occupying the size of each corner in the width direction.

[0048] More specifically, in order to maximize the use of the space at the corner, the corners between adjacent superconducting nanowires 2a in each detection unit 21 are configured to be convex toward the side away from the longer superconducting nanowire 2a. Figure 5 As shown, since the corners are staggered in sequence, the space on the shorter superconducting nanowire side is larger, so the inner boundary of the corner facing the longer superconducting nanowire is aligned with the spacing between the superconducting nanowires, and the inner boundary on the other side is raised.

[0049] More specifically, in this embodiment, the size of each corner in the width direction of the superconducting nanowire is greater than the width of the superconducting nanowire; the size of the corner between two adjacent detection units 21 in the width direction of the superconducting nanowire is equal to the spacing between the two adjacent detection units 21, that is, the spacing between two adjacent detection units 21 is greater than the spacing between adjacent superconducting nanowires 2a in the detection unit 21.

[0050] In the superconducting nanowire single-photon detector 2 of the present invention, the corners no longer compete for design space, so the radius of curvature of each corner can be as large as possible to reduce the current crowding effect. In the present invention, each corner is designed with the inner boundary shape described by formula (1). At this time, although a in formula (1) can be strictly constrained to be greater than or equal to 2 times the line width, thereby completely eliminating current crowding, slight current crowding does not significantly reduce the switching current of the device. Under the condition of acceptable crowding, considering the requirements of light absorption rate on line filling rate, the present invention can take a less than 2 times the line width, including but not limited to 1.9 times, 1.8 times, 1.7 times, 1.6 times, 1.5 times, 1.4 times (in specific use, it is configured according to actual needs, not limited to this embodiment), because slight current crowding does not significantly reduce the switching current of the device. As an example, in this embodiment, when designing the misaligned corners, a is taken to be equal to 1.625 times the line width; in particular, when the corners (spacing) between the detection units 21 are less than 2 times the line width, the filling rate can be more significantly improved.

[0051] like Figure 6 As shown, for performance comparison, refer to Figure 3 The parameters of the aligned corner superconducting single-photon detector 1 set the size of the superconducting nanowire single-photon detector 2 of the present invention, wherein the superconducting nanowire line width W2 is set to 80nm, the spacing S3 between adjacent superconducting nanowires in the same detection unit is set to 40nm, the spacing S4 between each detection unit (the size of the corner between each detection unit in the width direction of the superconducting nanowire) is set to 120nm, the size S5 of each misaligned corner in the detection unit in the width direction of the superconducting nanowire is set to 130nm, and the spacing S6 between adjacent corners aligned in the width direction is set to 100nm. Under this condition, Figure 4 As shown in the simulation results of the superconducting single-photon detector 1 aligned with the corners, the current follows the electric potential and is tightly constrained to flow at the inner boundary of each corner. There are high current density areas (orange and red areas) on the inner boundaries of all corners, that is, there is a serious current crowding effect; and according to Figure 7 As shown, in the staggered corner superconducting nanowire single-photon detector 2 of the present invention, the current in the first-level superconducting nanowire of the first detection unit flows into the first-level superconducting nanowire of the second detection unit, and the current in the second-level superconducting nanowire of the first detection unit flows into the second-level superconducting nanowire of the second detection unit, correspondingly. Since the current confinement areas of each level are staggered at a long distance and do not affect each other, the burden of each level of corners can be greatly reduced. Even if the size of each corner in the width direction does not reach 2 times the width of the nanowire, the current density on the boundary of each corner is still greatly reduced. More specifically, Figure 7 The maximum ratio of the current density at the inner boundary of each corner to the straight line current density is only 1.2. Figure 4The simulation result of the aligned corner (corresponding to a ratio of 1.7) was reduced by 50%, demonstrating from the simulation perspective that the staggered structure significantly alleviates the current crowding at the corners. In addition, compared with the corner alignment method, the spacing between the superconducting nanowires of the present invention can be further reduced. In theory, the present invention can reduce the line spacing inside the detection unit to 1 / 10 of the line width, and still have a significant optimization effect.

[0052] In this embodiment, a superconducting single-photon detector 1 aligned with a corner is fabricated on a 2-inch silicon dioxide substrate (see Figure 2 ) and the staggered corner superconducting nanowire single photon detector 2 of the present invention (see Figure 5 ) are 45 each, and the two are arranged in a chessboard pattern to eliminate the uncertainty introduced by the uniformity of the film and photoresist. Each detection unit includes two parallel superconducting nanowires. The film is made of 7nm thick niobium nitride (NbN). The line width, filling rate in the detection unit, detection unit spacing, corner shape and distribution are consistent with the design during simulation. The preparation process uses a conventional single-layer film detector process. The critical temperature of the film is about 7.6K.

[0053] In order to characterize the actual switching current I sw In this embodiment, a test circuit constructed by using a DC voltage source, Bias-T, and an acquisition card is used to improve the performance of the test circuit. Figure 2 and Figure 5 The IV curves of two batches of single-photon detectors with the same structure were measured, and the switching currents of all devices were counted. I sw (That is, the maximum current value when the voltage is 0). Figure 8 It can be seen that the switching current of the staggered corner superconducting nanowire single-photon detector of the present invention is I sw The distribution is more concentrated and the mean is at a higher level, with a mean of 26.73 μA and a standard deviation of 1.05; the switching current of the superconducting single-photon detector aligned with the corner I sw The mean value is 24.03 μA, the standard deviation is 2.01, and the mean value of the switch current of the present invention is increased by 11.2%, which statistically demonstrates the significant inhibitory effect of the present invention on the current crowding effect.

[0054] In order to characterize the performance improvement of the optimized structure of the present invention, one superconducting nanowire single-photon detector is selected from each of 45 staggered corners and 45 aligned corners (the switching currents of the two detectors are 27μA and 22.55μA, respectively), and the quantum efficiency and time jitter characteristics of the two are compared. Quantum efficiency can be evaluated by comparing the saturation of the efficiency curve, and time jitter requires counting the time-correlated single photon counts of the device, which is measured by counting the half-height full width of the peak. In this embodiment, the measuring equipment includes a voltage source, a low-noise amplifier, a Bias-T, and a high-bandwidth counter; the optical path system consists of a laser, an attenuator, and a polarizer, which are connected in sequence through optical fibers. Fig. 9 The normalized efficiency comparison of two single-photon detectors in the 1064nm band is shown. Fig.10 The comparison of time-correlated single photon counting of two single photon detectors at 1064nm is shown. Fig.11 The normalized efficiency comparison of two single-photon detectors in the 1550nm band is shown. Fig.12 The comparison of time-correlated single photon counts of two single-photon detectors at 1550nm is shown. The jitter measurement bias current is 91.35% of the switch current. Obviously, the staggered corner superconducting nanowire single-photon detector 2 shows higher quantum efficiency and smaller time jitter in both 1064nm and 1550nm bands, demonstrating that the present invention has a significant optimization effect on various aspects of the detector performance.

[0055] Furthermore, the detection units (2 superconducting nanowires in parallel) of each staggered corner of the present invention are prepared on a substrate with a reflector (such as a Bragg reflector) to obtain a higher system detection efficiency. In order to ensure the light absorption rate, the effective photosensitive surface diameter designed in this embodiment is 20μm, the filling rate is 50%, and a reflector substrate for the 1064nm band is used. As an example, the substrate is a 7nm niobium nitride film grown by magnetron sputtering, and the critical temperature of the film is about 7.2K. The detector structure parameters are consistent with the device without a reflector. As Fig.13 As shown, the system detection efficiency of the present invention for 1064nm laser can reach 96.6%, which exceeds the system detection efficiency of other single-photon detectors reported so far in the 1064nm band; in addition, the dark count rate (DCR) of the detector of the present invention is only about 20~30c.ps during saturation detection, and the comprehensive performance is excellent.

[0056] The present invention further provides a detection device including the superconducting nanowire single-photon detector 2 of the present invention, which will not be described in detail here.

[0057] In summary, the present invention provides a superconducting nanowire single-photon detector and a detection device, comprising: a plurality of detection units cascaded in sequence and arranged in a winding manner, each detection unit comprising at least two parallel superconducting nanowires; wherein adjacent corners are staggered in the width direction of the superconducting nanowires, and the size of each corner in the width direction of the superconducting nanowires is greater than the spacing between adjacent superconducting nanowires in the detection unit. The present invention aims to alleviate the current crowding effect of parallel nanowire superconducting single-photon detectors, expand the corner design space by staggered placement, decouple the corner curvature radius inside the detection unit from the filling rate, and achieve the purpose of alleviating the current crowding effect under high filling rate and improving the detection efficiency of the system. The design structure of the present invention is simple and the optimization effect is significant; at the same time, there is no need to introduce additional preparation processes, there is no damage to the film and the process is robust; in addition, it occupies a small area on the chip, which is conducive to integrated design. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0058] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A superconducting nanowire single-photon detector, characterized in that: The superconducting nanowire single-photon detector comprises: A plurality of detection units cascaded in sequence and arranged in a winding manner, each detection unit comprising at least two superconducting nanowires connected in parallel; Wherein, adjacent corners are staggered in the width direction of the superconducting nanowire, and the size of each corner in the width direction of the superconducting nanowire is larger than the spacing between adjacent superconducting nanowires in the detection unit.

2. The superconducting nanowire single-photon detector according to claim 1, characterized in that: The corners on the connecting sides of adjacent detection units are arranged in a staggered manner from the inside to the outside in a direction away from the center line between the adjacent detection units; and the corresponding level corners in the adjacent detection units are aligned in the width direction.

3. The superconducting nanowire single-photon detector according to claim 2, characterized in that: The spacing between the corresponding level corners at the connection sides of adjacent detection units in the width direction is greater than the line width of the superconducting nanowire.

4. The superconducting nanowire single-photon detector according to claim 2, characterized in that: The lengths of the superconducting nanowires in the same detection unit are equal.

5. The superconducting nanowire single-photon detector according to claim 2, characterized in that: The corners between adjacent superconducting nanowires in each detection unit are convex toward the side away from the longer superconducting nanowire.

6. The superconducting nanowire single-photon detector according to any one of claims 1 to 5, characterized in that: The dimension of each corner in the width direction of the superconducting nanowire is larger than the width of the superconducting nanowire.

7. The superconducting nanowire single-photon detector according to any one of claims 1 to 5, characterized in that: The number of superconducting nanowires connected in parallel in each detection unit is equal, and the number of superconducting nanowires connected in parallel is set to 2-10; Each superconducting nanowire comprises 1 to 5 stacked superconducting nanomaterial layers. When the number of superconducting nanomaterial layers is greater than or equal to 2, an electrical isolation layer is further provided between each superconducting nanomaterial layer.

8. The superconducting nanowire single-photon detector according to any one of claims 1 to 5, characterized in that: The detection units are arranged in parallel and arranged in sequence in the width direction of the superconducting nanowire.

9. The superconducting nanowire single-photon detector according to any one of claims 1 to 5, characterized in that: Each detection unit is prepared on a substrate with a reflecting mirror.

10. A detection device, characterized in that: The detection device at least includes the superconducting nanowire single-photon detector as described in any one of claims 1-9.

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