Single photon detection up to 2 µm in pair of parallel microstrips based on NbRe ultrathin films.

Superconducting microstrip single photon detectors (SMSPDs) are increasingly attracting the interest of the scientific community as a new platform for large area detectors with unprecedented advantaged in terms of fabrication. However, while their operativity at the telecommunication wavelength was achieved, working beyond 1.55 µm is challenging. Here, we experimentally demonstrate single-photon operation of NbRe microstrips at wavelengths of 1.55 and 2 µm. The devices are structured as pairs of parallel microstrips with widths ranging from 1.4 to 2.2 µm and lengths from 5 to 10 µm. This innovative design may assure large sensitive areas, without affecting the kinetic inductance, namely the time performance of the detectors. The results are discussed in the framework of the hot-spot two-temperature model.

Author Correction: Superconductor to resistive state switching by multiple fluctuation events in NbTiN nanostrips.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Superconductor to resistive state switching by multiple fluctuation events in NbTiN nanostrips.

We report on measurements of the switching current distributions on two-dimensional superconducting NbTiN strips that are 5 nm thick and 80 nm wide. We observe that the width of the switching current distributions has a non-monotonous temperature dependence, where it is constant at the lowest temperatures up to about 1.5 K, after which it increases with temperature until 2.2 K. Above 2.5 K any increase in temperature decreases the distribution width which at 4.0 K is smaller than half the width observed at 0.3 K. By using a careful analysis of the higher order moments of the switching distribution, we show that this temperature dependence is caused by switching due to multiple fluctuations. We also find that the onset of switching by multiple events causes the current dependence of the switching rate to develop a characteristic deviation from a pure exponential increase, that becomes more pronounced at higher temperatures, due to the inclusion of higher order terms.

Use of recombinant LH in a group of unselected IVF patients.

The aim of this study was to evaluate the use of recombinant luteinizing hormone (rLH) supplementation in an unselected group of IVF patients undergoing follicular stimulation with recombinant follicle stimulating hormone (rFSH) after pituitary down-regulation. Group A comprised 122 cycles administered rFSH and rLH while group B included 331 cycles using rFSH only during the same period of treatment. There was no significant difference in any of the endocrine, embryological and outcome parameters measured. The implantation rate of 14.2% for group A compared with 9.8% for group B showed a positive trend (P = 0.055), but for patients in whom LH concentration was <1.0 IU/l at down-regulation or required excessive FSH stimulation, there was an increased incidence of implantation if rLH was supplemented. It was concluded that the addition of exogenous rLH to an unselected group of 'down-regulated' patients stimulated with rFSH appears to offer little benefit, but in the event of profound LH down-regulation or requirement for excessive exogenous FSH (>2500 IU), the rate of implantation might be improved.