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At least 19 records

Characterization of High Speed Optical and Magnetic Interactions in Superconducting Nanowire Single Photon Detectors

Single-photon detectors are essential tools for quantum photonics. The ideal single photon detector would exhibit a quantum efficiency (QE) of 100% (i.e. no false negatives), zero dark photon counts per second (i.e. no false positives), zero dead time (i.e. the detector is capable of detecting one photon immediately after another), and zero jitter (i.e. the electrical signal produced by the detector perfectly reproduces the timing of the input photon signal). Commercially available avalanche photodiodes (APDs) have generally performed reasonably well for visible wavelengths but they perform poorly at longer wavelengths. For wavelengths spanning the near- ultraviolet (UV) to the mid- infrared (IR), superconducting nanowire single photon detectors (SNSPDs) can exhibit quantum efficiencies exceeding 90% with dark count rates and timing jitter roughly an order of magnitude less than is typically seen in APDs. While SNSPDSs are now commercially available from several small businesses, fundamental questions about the nature of photon interactions with superconducting nanostructures remain.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Waveform analysis of a large-area superconducting nanowire single photon detector

Superconducting nanowire single photon detectors (SNSPDs) are typically used as single-mode-fiber-coupled single-pixel detectors, but large area detectors are increasingly critical for applications ranging from microscopy to free-space quantum communications. However, the long meander-line length of such large-area SNSPDs results in a proportionately large kinetic inductance that affects the waveform generated by the device. Here, we explore changes in the rising edge of the readout pulse for a single-pixel large-area SNSPD as a function of the optical spot size on the detector and compare to the rising edge of the dark-count waveform. We observe a bimodal distribution of bright-count rise times and show that the probability of a slow rise time increases in the limit of large spot sizes, indicative of a position sensitive response. Additionally, in the limit of low bias currents, the dark-count readout pulse is most similar to the large spot-size bright-count readout pulse, which suggests that dark counts arise from locations spanning the device. Overall, these results are consistent with a simple model of traveling microwave modes excited by single photons incident at varying positions along the length of the nanowire.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Unconventional Applications of Superconducting Nanowire Single Photon Detectors

Superconducting nanowire single photon detectors are becoming a dominant technology in quantum optics and quantum communication, primarily because of their low timing jitter and capability to detect individual low-energy photons with high quantum efficiencies. However, other desirable characteristics, such as high detection rates, operation in cryogenic and high magnetic field environments, or high-efficiency detection of charged particles, are underrepresented in literature, potentially leading to a lack of interest in other fields that might benefit from this technology. We review the progress in use of superconducting nanowire technology in photon and particle detection outside of the usual areas of physics, with emphasis on the potential use in ongoing and future experiments in nuclear and high energy physics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Radiation-Induced Dark Counts for Silicon Single-Photon Detectors in Space

Single-photon detectors operating on satellites for use in a quantum communications network can incur large dark-count-rate increases from the natural radiation environment of space. Displacement damage to the material lattice of a detector from the ionizing radiation can result in a permanent dark-count increase in the detector. In this work, we analyze the radiation-induced dark-count rate of a silicon single-photon avalanche diode onboard a satellite at different orbiting altitudes, as well as, the additional radiation from a nuclear-disturbed environment caused by a high-altitude nuclear explosion. For detectors on low Earth orbit satellites, protons are the biggest source of radiation damage and are best mitigated by choosing an orbit that minimizes exposure when passing through the South Atlantic Anomaly and Polar Cusps. Detectors on medium Earth orbit and geostationary orbit satellites, if shielded by more than 10 mm of aluminum, provide the best platform in terms of the least amount of radiation damage to the detectors. In the event of a high-altitude nuclear explosion, the artificial radiation belts produced by the explosion will cause too much damage to silicon single-photon detectors on low Earth orbit satellites and render them unfit for quantum communications in less than a day. Higher orbit satellites will only suffer minor dark-count-rate increases from the artificial radiation belts.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

Nb(x)Ti(1-x)N Superconducting-Nanowire Single-Photon Detectors

Superconducting-nanowire single-photon detectors (SNSPDs) in which Nb(x)Ti(1-x)N (where x<1) films serve as the superconducting materials have shown promise as superior alternatives to previously developed SNSPDs in which NbN films serve as the superconducting materials. SNSPDs have potential utility in optical communications and quantum cryptography. Nb(x)Ti(1-x)N is a solid solution of NbN and TiN, and has many properties similar to those of NbN. It has been found to be generally easier to stabilize Nb(x)Ti(1-x)N in the high-superconducting-transition temperature phase than it is to so stabilize NbN. In addition, the resistivity and penetration depth of polycrystalline films of Nb(x)Ti(1-x)N have been found to be much smaller than those of films of NbN. These differences have been hypothesized to be attributable to better coupling at grain boundaries within Nb(x)Ti(1-x)N films.

Stern, Jeffrey A.↗

Lithium-niobate-on-insulator waveguide-integrated superconducting nanowire single-photon detectors

Here, we demonstrate waveguide-integrated superconducting nanowire single-photon detectors on thin-film lithium niobate (LiNbO 3 , LN). Using a 250 μm-long NbN superconducting nanowire lithographically defined on top of a 125 μm-long LN nanowaveguide, an on-chip detection efficiency of 46% is realized with simultaneous high performance in dark count rates and timing jitter. As LN possesses high χ (2) second-order nonlinear and electro-optic properties, an efficient single-photon detector on thin-film LN opens up the possibility to construct a small-scale fully integrated quantum photonic chip, which includes single-photon sources, filters, tunable quantum gates, and detectors.

42 ENGINEERING↗

Waveguide-Coupled Superconducting Nanowire Single-Photon Detectors

We have demonstrated WSi-based superconducting nanowire single-photon detectors coupled to SiNx waveguides with integrated ring resonators. This photonics platform enables the implementation of robust and efficient photon-counting detectors with fine spectral resolution near 1550 nm.

Beyer, Andrew D.↗

Fabrication and Characterization of Superconducting NbN Nanowire Single Photon Detectors

We report on the fabrication and characterization of high-speed, single photon detectors using superconducting NbN nanowires at a wavelength of 1064 nm. A 15 by 15 micron detector with a detector efficiency of 40% has been measured. Due to kinetic inductance, the recovery time of such large area detectors is longer than that of smaller or single wire detectors. The recovery time of our detectors (50 ns) has been characterized by measuring the inter-arrival time statistics of our detector.

single proton detectors↗

Fabrication and Characterization of Superconducting NbN Nanowire Single Photon Detectors

This viewgraph presentation describes the fabrication of large area superconducting Niobium Nitride nanowire single photon detectors. The topics include: 1) Introduction and Motivation; 2) Operation of SNSPD Detectors; 3) NbTiN Deposition; 4) Fabrication Details; 5) Backside Coupled SNSPD; 6) Measurement Apparatus; 7) Electrical Response of a 15x15 micrometer SNSPD to 1064nm radiation; 8) Detector Efficiency vs Bias Current; 9) Interarrival Time Plot; 10) Detector Linearity; and 11) Conclusion.

single proton dectectors↗

Performance and Characterization of a Modular Superconducting Nanowire Single Photon Detector System for Space-to-Earth Optical Communications Links

Space-to-ground photon-counting optical communication links supporting high data rates over large distances require enhanced ground receiver sensitivity in order to reduce the mass and power burden on the spacecraft transmitter. Superconducting nanowire single-photon detectors (SNSPDs) have been demonstrated to offer superior performance in detection efficiency, timing resolution, and count rates over semiconductor photodetectors, and are a suitable technology for high photon efficiency links. Recently photon detectors based on superconducting nanowires have become commercially available, and we have assessed the characteristics and performance of one such commercial system as a candidate for potential utilization in ground receiver designs. The SNSPD system features independent channels which can be added modularly, and we analyze the scalability of the system to support different data rates, as well as consider coupling concepts and issues as the number of channels increases.

Superconductors↗

Data for "Understanding multiscale disorder in superconducting nanowire single photon detectors"

This dataset addresses DC transport, dark-count measurements, and bias-dependent microwave transmission spectroscopy of superconducting nanowire. This publication includes the raw and processed data to produce figures in the paper "Understanding multiscale disorder in superconducting nanowire single photon detectors" (Sarkar et al., 2026).

Sarkar, Nirjhar [Oak Ridge National Laboratory] (O↗

Few-Mode Fiber Coupled Superconducting Nanowire Single-Photon Detectors for Photon Efficient Optical Communications

The NASA Glenn Research Center's development of a high-photon efficiency real-time optical communications ground receiver has added superconducting nanowire single-photon detectors (SNSPDs) coupled with few-mode fibers (FMF). High data rate space-to-ground optical communication links require enhanced ground receiver sensitivity to reduce spacecraft transmitter constraints, and therefore require highly efficient coupling from fiber to detector. In the presence of atmospheric turbulence the received optical wave front can be severely distorted introducing higher-order spatial mode components to the received signal. To reduce mode filtering and mismatch loss and the resulting degradations to detector coupling efficiency, we explore the use of few-mode fiber coupling to commercial single-pixel SNSPDs. Graded index 20-µm few-mode fibers allow the commercial single pixel SNSPD's active area to couple with equal efficiency as single mode fibers. Here we determine detector characteristics such as count rate, detection efficiency, dark counts, and jitter, as well as detection efficiencies for higher-order fiber spatial modes. Additionally, we assess the laboratory performance of the detectors in an optical system which emulates future deep space optical communications links.

Vyhnalek, Brian E.↗

Superconducting nanowire single-photon detector enhanced near-infrared II portable confocal microscopy for tissue imaging with indocyanine green

In this Letter a novel, to our knowledge, approach for near-infrared (NIR) fluorescence portable confocal microscopy is introduced, aiming to enhance fluorescence imaging of biological samples in the NIR-II window. By integrating a superconducting nanowire single-photon detector (SNSPD) into a confocal microscopy, we have significantly leveraged the detection efficiency of the NIR-II fluorescence signal from indocyanine green (ICG), an FDA-approved dye known for its NIR-II fluorescence capabilities. The SNSPD, characterized by its extremely low dark count rate and optimized NIR system detection efficiency, enables the excitation of ICG with 1 mW and the capture of low-light fluorescence signals from deep regions (up to 512 µm). Consequently, our technique was able to produce high-resolution images of bio samples with a superior signal-to-noise ratio, making a substantial advancement in the field of fluorescence microscopy and offering a promising opportunity for future clinical study.

Liu, Yifan (ORCID:0000000328877704)↗

Interferometric Quantum-Nondemolition Single-Photon Detectors

Two interferometric quantum-nondemolition (QND) devices have been proposed: (1) a polarization-independent device and (2) a polarization-preserving device. The prolarization-independent device works on an input state of up to two photons, whereas the polarization-preserving device works on a superposition of vacuum and single- photon states. The overall function of the device would be to probabilistically generate a unique detector output only when its input electromagnetic mode was populated by a single photon, in which case its output mode would also be populated by a single photon. Like other QND devices, the proposed devices are potentially useful for a variety of applications, including such areas of NASA interest as quantum computing, quantum communication, detection of gravity waves, as well as pedagogical demonstrations of the quantum nature of light. Many protocols in quantum computation and quantum communication require the possibility of detecting a photon without destroying it. The only prior single- photon-detecting QND device is based on quantum electrodynamics in a resonant cavity and, as such, it depends on the photon frequency. Moreover, the prior device can distinguish only between one photon and no photon. The proposed interferometric QND devices would not depend on frequency and could distinguish between (a) one photon and (b) zero or two photons. The first proposed device is depicted schematically in Figure 1. The input electromagnetic mode would be a superposition of a zero-, a one-, and a two-photon quantum state. The overall function of the device would be to probabilistically generate a unique detector output only when its input electromagnetic mode was populated by a single photon, in which case its output mode also would be populated by a single photon.

Kok, Peter↗