Abstract: Superconducting Single Photon Detectors (SSPD) are now mature enough to provide extremely interesting detector performances in term of sensitivity, speed, and geometry in the visible and near infrared wavelengths. Taking advantage of recent results obtained in the Sinphonia project, the goal of our research is to demonstrate the feasibility of a new family of micro-spectrometers, called SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer), associated to an array of SSPD, the whole assembly being integrated on a monolithic sapphire substrate coupling the detectors array to a waveguide injecting the light. This unique association will create a major breakthrough in the domain of visible and infrared spectroscopy for all applications where the space and weight of the instrument is limited. SWIFTS is an innovative way to achieve very compact spectro-detectors using nano-detectors coupled to evanescent field of dielectric integrated optics. The system is sensitive to the interferogram inside the dielectric waveguide along the propagation path. Astronomical instruments will be the first application of such SSPD spectrometers. In this paper, we describes in details the fabrication process of our SSPD built at CEA/DRFMC using ultra-thin NbN epitaxial films deposited on different orientations of Sapphire substrates having state of the art superconducting characteristics. Electron beam lithography is routinely used for patterning the devices having line widths below 200 nm and down to 70 nm. An experimental set-up has been built and used to test these SSPD devices and evaluate their photon counting performances. Photon counting performances of our devices have been demonstrated with extremely low dark counts giving excellent signal to noise ratios. The extreme compactness of this concept is interesting for space spectroscopic applications. Some new astronomical applications of such concept are proposed in this paper.

Abstract: We present our latest generation of ultrafast superconducting NbN single-photon detectors (SSPD) capable of photon-number resolving (PNR). We have developed, fabricated and tested a multi-sectional design of NbN nanowire structures. The novel SSPD structures consist of several meander sections connected in parallel, each having a resistor connected in series. The novel SSPDs combine 10 μm × 10 μm active areas with a low kinetic inductance and PNR capability. That resulted in a significantly reduced photoresponse pulse duration, allowing for GHz counting rates. The detector's response magnitude is directly proportional to the number of incident photons, which makes this feature easy to use. We present experimental data on the performances of the PNR SSPDs. The PNR SSPDs are perfectly suited for fibreless free-space telecommunications, as well as for ultrafast quantum cryptography and quantum computing.

Abstract: We present our progress in the development of superconducting single-photon detectors (SSPDs) based on meander-shaped nanowires made from few-nm-thick superconducting films. The SSPDs are operated at a temperature of 2–4.2 K (well below T c ) being biased with a current very close to the nanowire critical current at the operation temperature. To date, the material of choice for SSPDs is niobium nitride (NbN). Developed NbN SSPDs are capable of single photon counting in the range from VIS to mid-IR (up to 6 μm) with a record low dark counts rate and record-high counting rate. The use of a material with a low transition temperature should shift the detectors sensitivity towards longer wavelengths. We present state-of-the art NbN SSPDs as well as the results of our recent approach to expand the developed SSPD technology by the use of superconducting materials with lower T c , such as molybdenum rhenium (MoRe). MoRe SSPDs first were made and tested; a single photon response was obtained.

Abstract: The authors present a fabrication technique of superconducting single photon detectors made by local oxidation of niobium nitride ultrathin films. Narrow superconducting meander lines are obtained by direct writing of insulating niobium oxynitride lines through the films using voltage-biased tip of an atomic force microscope. Due to the 30nm resolution of the lithographic technique, the filling factor of the meander line can be made substantially higher than detector of similar geometry made by electron beam lithography, thus leading to increased quantum efficiency. Single photon detection regime of these devices is demonstrated at 4.2K.
The authors thank J.-P. Maneval for stimulating discussions. This work has been partly supported by ACI Nanoscience from French Ministry of Research, D.G.A., by Grant No. 02.445.11.7434 of Russian Ministry of Education and Science, and by the European Commission under project “SINPHONIA,” Contract No. NMP4-CT-2005-16433.

Abstract: We present an overview of the state-of-the-art of NbN superconducting single-photon detectors (SSPDs). Our devices exhibit quantum efficiency (QE) of up to 30% in near-infrared wavelength and 0.4% at 5 mum, with a dark-count rate that can be as low as 10 -4 s -1 . The SSPD structures integrated with lambda/4 microcavities achieve a QE of 60% at telecommunication, 1550-nm wavelength. We have also developed a new generation of SSPDs that possess the QE of large-active-area devices, but, simultaneously, are characterized by low kinetic inductance that allows achieving short response times and the GHz-counting rate with picosecond timing jitter. The improvements presented in the SSPD development, such as fiber-coupled SSPDs, make our detectors most attractive for high-speed quantum communications and quantum computing.