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We present a simple experimental scheme for estimating the cryogenic thermal transport properties of thin films using superconducting nanowires. In a parallel array of nanowires, the heat from one nanowire in the normal state changes the local temperature around adjacent nanowires, reducing their switching current. Calibration of this change in switching current as a function of bath temperature provides an estimate of the temperature as a function of displacement from the heater. This provides a method of determining the contribution of substrate heat transport to the cooling time of superconducting nanowire single-photon detectors. Understanding this process is necessary for successful electrothermal modeling of superconducting nanowire systems. [ABSTRACT FROM AUTHOR]

There are both fundamental and practical motivations for studying whether quantum entanglement can exist in macroscopic systems. However, multiparty entanglement is generally fragile and difficult to quantify. Dicke states are multiparty entangled states where a single excitation is delocalized over many systems. Building on previous work on quantum memories for photons, we create a Dicke state in a solid by storing a single photon in a crystal that contains many large atomic ensembles with distinct resonance frequencies. The photon is re-emitted at a well-defined time due to an interference effect analogous to multi-slit diffraction. We derive a lower bound for the number of entangled ensembles based on the contrast of the interference and the single-photon character of the input, and we experimentally demonstrate entanglement between over two hundred ensembles, each containing a billion atoms. We also illustrate the fact that each individual ensemble contains further entanglement. [ABSTRACT FROM AUTHOR]

Single-photon detectors at near-infrared wavelengths with high system detection efficiency (>90%), low dark count rate (<1 c.p.s.), low timing jitter (<100 ps) and short reset time (<100 ns) would enable landmark experiments in a variety of fields. Although some of the existing approaches to single-photon detection fulfil one or two of the above specifications, to date, no detector has met all of the specifications simultaneously. Here, we report on a fibre-coupled single-photon detection system that uses superconducting nanowire single-photon detectors and closely approaches the ideal performance of single-photon detectors. Our detector system has a system detection efficiency (including optical coupling losses) greater than 90% in the wavelength range λ = 1,520-1,610 nm, with a device dark count rate (measured with the device shielded from any background radiation) of ∼1 c.p.s., timing jitter of ∼150 ps full-width at half-maximum (FWHM) and reset time of 40 ns. [ABSTRACT FROM AUTHOR]

In 2002 the Italian Standardisation Organisation (UNI) - Nuclear Energy Commission (UNICEN) - appointed a working group with the main task of writing a set of standards on drinking water measurements. To date two standards have been designed, namely, for total alpha- and beta-activity, and 222Rn. Further procedures are under development for measuring 226Ra and U isotopes, and gamma-emitting radionuclides in water. The paper gives an overview of these standards, both developed and under study, with special attention to the validation of the methods. [ABSTRACT FROM AUTHOR]