We report on MoSi SNSPDs which achieved high system detection efficiency (87.1 ± 0.5% at 1542 nm) at 0.7 K and we demonstrate that these detectors can also be operated with saturated internal ...efficiency at a temperature of 2.3 K in a Gifford-McMahon cryocooler. We measured a minimum system jitter of 76 ps, maximum count rate approaching 10 MHz, and polarization dependence as low as 3.3 ± 0.1%. The performance of MoSi SNSPDs at 2.3 K is similar to the performance of WSi SNSPDs at < 1 K. The higher operating temperature of MoSi SNSPDs makes these devices promising for widespread use due to the simpler and less expensive cryogenics required for their operation.
For photon-counting applications at ultraviolet wavelengths, there are currently no detectors that combine high efficiency (> 50%), sub-nanosecond timing resolution, and sub-Hz dark count rates. ...Superconducting nanowire single-photon detectors (SNSPDs) have seen success over the past decade for photon-counting applications in the near-infrared, but little work has been done to optimize SNSPDs for wavelengths below 400 nm. Here, we describe the design, fabrication, and characterization of UV SNSPDs operating at wavelengths between 250 and 370 nm. The detectors have active areas up to 56 μm in diameter, 70 - 80% efficiency at temperatures up to 4.2 K, timing resolution down to 60 ps FWHM, blindness to visible and infrared photons, and dark count rates of ∼ 0.25 counts/hr for a 56 μm diameter pixel. These performance metrics make UV SNSPDs ideal for applications in trapped-ion quantum information processing, lidar studies of the upper atmosphere, UV fluorescent-lifetime imaging microscopy, and photon-starved UV astronomy.
We developed superconducting nanowire single-photon detectors based on tungsten silicide, which show saturated internal detection efficiency up to a wavelength of 10 μm. These detectors are promising ...for applications in the mid-infrared requiring sub-nanosecond timing, ultra-high gain stability, low dark counts, and high efficiency, such as chemical sensing, LIDAR, dark matter searches, and exoplanet spectroscopy.
We present a compactly integrated, 625 MHz clocked coherent one-way quantum key distribution system which continuously distributes secret keys over an optical fibre link. To support high secret key ...rates, we implemented a fast hardware key distillation engine which allows for key distillation rates up to 4 Mbps in real time. The system employs wavelength multiplexing in order to run over only a single optical fibre. Using fast gated InGaAs single photon detectors, we reliably distribute secret keys with a rate above 21 kbps over 25 km of optical fibre. We optimized the system considering a security analysis that respects finite-key-size effects, authentication costs and system errors for a security parameter of QKD = 4 × 10−9.
We demonstrate the violation of an Einstein-Podolsky-Rosen steering inequality developed for single-photon path entanglement with displacement-based detection. We use a high-rate source of heralded ...single-photon path-entangled states, combined with high-efficiency superconducting-based detectors, in a scheme that is free of any postselection and thus immune to the detection loophole. This result conclusively demonstrates single-photon entanglement in a one-sided device-independent scenario, and opens the way towards implementations of device-independent quantum technologies within the paradigm of path entanglement.
We estimate the depairing current of superconducting nanowire single-photon detectors (SNSPDs) by studying the dependence of the nanowires' kinetic inductance on their bias current. The kinetic ...inductance is determined by measuring the resonance frequency of resonator-style nanowire coplanar waveguides both in transmission and reflection configurations. Bias current dependent shifts in the measured resonant frequency correspond to the change in the kinetic inductance, which can be compared with theoretical predictions. We demonstrate that the fast relaxation model described in the literature accurately matches our experimental data and provides a valuable tool for determination of the depairing current. Accurate measurement of the depairing current is critical for nanowire quality analysis, as well as modeling efforts aimed at understanding the detection mechanism in SNSPDs.
The problems of introduction of agile methodologies in the process of functioning of domestic enterprises in the field of engineering services are investigated. The main reasons for the transition ...from the traditional cascade model of project team management to agile technologies, in particular, Scrum and Kanban, are identified. The main stages of implementation of engineering service based on Scrum and Kanban methodologies according to the level of organizational maturity of the enterprise are distinguished. A combined Scrum-Kanban adaptive model has been created to enable Agile principles to be implemented in a team management system at engineering services.
Improving the temporal resolution of single photon detectors has an impact on many applications, such as increased data rates and transmission distances for both classical and quantum optical ...communication systems, higher spatial resolution in laser ranging and observation of shorter-lived fluorophores in biomedical imaging. In recent years, superconducting nanowire single-photon detectors (SNSPDs) have emerged as the highest efficiency time-resolving single-photon counting detectors available in the near infrared. As the detection mechanism in SNSPDs occurs on picosecond time scales, SNSPDs have been demonstrated with exquisite temporal resolution below 15 ps. We reduce this value to 2.7\(\pm\)0.2 ps at 400 nm and 4.6\(\pm\)0.2 ps at 1550 nm, using a specialized niobium nitride (NbN) SNSPD. The observed photon-energy dependence of the temporal resolution and detection latency suggests that intrinsic effects make a significant contribution.
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