Timing performance of 30-nm-wide superconducting nanowire avalanche photodetectors

We investigated the timing jitter of superconducting nanowire avalanche photodetectors (SNAPs, also referred to as cascade switching superconducting single photon detectors) based on 30-nm-wide nanowires. At bias currents (IB) near the switching current, SNAPs showed sub 35 ps FWHM Gaussian jitter similar to standard 100 nm wide superconducting nanowire single-photon detectors. At lower values of IB, the instrument response function (IRF) of the detectors became wider, more asymmetric, and shifted to longer time delays. We could reproduce the experimentally observed IRF time-shift in simulations based on an electrothermal model, and explain the effect with a simple physical picture

A review of energy efficient systems integrated into building envelopes

There is an essential need to reduce energy consumption in building sector as it consumes about 40 percent of the world energy and causes environmental problems. About fifty percent of energy in the building sector is used for heating, cooling and air conditioning purposes. Considering building envelopes as particular building elements with many functions which its energetic function is the most important one influencing building energy consumption, enhancing the thermal and energy efficiency of envelopes would decrease energy consumption of the buildings. Building envelopes contain roofs, external walls which are in touch with the outside environment and the floors on the ground. This paper would review a brief history of envelopes evolution and introduce a categorization for the envelopes based on different strategies for enhancing energetic function. A huge literature review on building envelopes has been done to identify different techniques. The result is summarized in five strategies as energy generation, cooling and heating, sun radiation control, and Thermal moderation and adaptive

When challenges hinder: An investigation of buyer-imposed stressors on supplier flexibility

Working with buyers may drive business growth but can also induce supplier stress. Drawing on Job Demands–Resources (JD-R) theory, this study explored how buyer-imposed work stressors affect supplier flexibility. Employing a scenario-based experiment involving 338 managers, we found that the imposition of challenge stressors increases supplier flexibility when hindrance stressors are low. Conversely, when hindrance stressors are high, imposing challenge stressors reduces supplier flexibility. We also found that supplier bricolage negatively moderates the relationship between buyer-imposed challenge stressors and supplier flexibility. Specifically, we confirmed that suppliers with higher bricolage are less willing to provide flexibility in response to challenge stressors. For practitioners, our study not only identified the type of work stressors they should impose on suppliers to boost flexibility but also highlighted bricolage as an important moderating factor

Free space-coupled superconducting nanowire single photon detectors for infrared optical communications

This paper describes the construction of a cryostat and an optical system with a free-space coupling efficiency of 56.5% +/- 3.4% to a superconducting nanowire single-photon detector (SNSPD) for infrared quantum communication and spectrum analysis. A 1K pot decreases the base temperature to T = 1.7 K from the 2.9 K reached by the cold head cooled by a pulse-tube cryocooler. The minimum spot size coupled to the detector chip was 6.6 +/- 0.11 {\mu}m starting from a fiber source at wavelength, {\lambda} = 1.55 {\mu}m. We demonstrated efficient photon counting on a detector with an 8 x 7.3 {\mu}m^2 area. We measured a dark count rate of 95 +/- 3.35 kcps and a system detection efficiency of 1.64% +/- 0.13%. We explain the key steps that are required to further improve the coupling efficiency.Comment: 16 pages, double-space

A Simplest Swimmer at Low Reynolds Number: Three Linked Spheres

We propose a very simple one-dimensional swimmer consisting of three spheres that are linked by rigid rods whose lengths can change between two values. With a periodic motion in a non-reciprocal fashion, which breaks the time-reversal symmetry as well as the translational symmetry, we show that the model device can swim at low Reynolds number. This model system could be used in constructing molecular-size machines

An Approximate Solution of the Mathieu Fractional Equation by Using the Generalized Differential Transform Method (Gdtm)

The generalized differential transform method (GDTM) is a powerful tool for solving fractional equations. In this paper we solve the Mathieu fractional equation by this method. The approximate solutions obtained are compared with the exact solution. We also show that if both differential orders decrease, we can still have an approximate solution in the different interval of p

Afterpulsing and instability in superconducting nanowire avalanche photodetectors

We investigated the reset time of superconducting nanowire avalanche photodetectors (SNAPs) based on 30 nm wide nanowires. We studied the dependence of the reset time of SNAPs on the device inductance and discovered that SNAPs can provide a speed-up relative to superconducting nanowire single-photon detectors with the same area but with some limitations: (1) Reducing the series inductance of SNAPs (necessary for the avalanche formation) could result in the detectors operating in an unstable regime, (2) a trade-off exists between maximizing the bias current margin and minimizing the reset time of SNAPs, and (3) reducing the reset time of SNAPs below ∼1 ns resulted in afterpulsing.United States. Intelligence Advanced Research Projects ActivityUnited States. Air Force (Air Force Contract No. FA8721-05-C-0002)United States. Dept. of Energy. Center for Excitonics (Award No. DE-SC0001088