Single-photon detection using large-scale high-temperature MgB sensors at 20 K.

Ultra-fast single-photon detectors with high current density and operating temperature can benefit space and ground applications, including quantum optical communication systems, lightweight cryogenics for space crafts, and medical use. Here we demonstrate magnesium diboride (MgB) thin-film superconducting microwires capable of single-photon detection at 1.55  μm optical wavelength.

Superconducting nanowire single-photon detector with 3D-printed free-form microlenses.

We present an approach to increase the effective light-receiving area of superconducting nanowire single-photon detectors (SNSPD) by free-form microlenses. These lenses are printed in situ on top of the sensitive detector areas using high-resolution multi-photon lithography. We demonstrate a detector based on niobium-nitride (NbN) nanowires with a 4.

Dynamics of a rolling robot.

Equations describing the rolling of a spherical ball on a horizontal surface are obtained, the motion being activated by an internal rotor driven by a battery mechanism. The rotor is modeled as a point mass mounted inside a spherical shell and caused to move in a prescribed circular orbit relative to the shell. The system is described in terms of four independent dimensionless parameters.

Proof of concept of fiber dispersed Raman spectroscopy using superconducting nanowire single-photon detectors.

Due to its high molecular specificity, Raman spectroscopy is a well-established analytical tool. Usually the inelastically scattered Raman light is spectrally dispersed by a spectrometer. Here, we present an alternative method, using an optical fiber as dispersive element.

Microbunching instability in relativistic electron bunches: direct observations of the microstructures using ultrafast YBCO detectors.

Relativistic electron bunches circulating in accelerators are subjected to a dynamical instability leading to microstructures at millimeter to centimeter scale. Although this is a well-known fact, direct experimental observations of the structures, or the field that they emit, remained up to now an open problem. Here, we report the direct, shot-by-shot, time-resolved recording of the shapes (including envelope and carrier) of the pulses of coherent synchrotron radiation that are emitted, and that are a "signature" of the electron bunch microstructure.

An asymptotic model in acoustics: acoustic drift equations.

A rigorous asymptotic procedure with the Mach number as a small parameter is used to derive the equations of mean flows which coexist and are affected by the background acoustic waves in the limit of very high Reynolds number.

Linear and nonlinear optical characterization of aluminum nanoantennas.

We experimentally determine the order of multiphoton induced luminescence of aluminum nanoantennas fabricated on a nonconductive substrate using electron-beam lithography to be 2.11 (±0.10).

Superconducting single-photon counting system for optical experiments requiring time-resolution in the picosecond range.

We have developed a cryogenic measurement system for single-photon counting, which can be used in optical experiments requiring high time resolution in the picosecond range. The system utilizes niobium nitride superconducting nanowire single-photon detectors which are integrated in a time-correlated single-photon counting (TCSPC) setup. In this work, we describe details of the mechanical design, the electrical setup, and the cryogenic optical components.

Orthogonal sequencing multiplexer for superconducting nanowire single-photon detectors with RSFQ electronics readout circuit.

We propose an efficient multiplexing technique for superconducting nanowire single-photon detectors based on an orthogonal detector bias switching method enabling the extraction of the average count rate of a set of detectors by one readout line. We implemented a system prototype where the SNSPDs are connected to an integrated cryogenic readout and a pulse merger system based on rapid single flux quantum (RSFQ) electronics. We discuss the general scalability of this concept, analyze the environmental requirements which define the resolvability and the accuracy and demonstrate the feasibility of this approach with experimental results for a SNSPD array with four pixels.

Deterministic Josephson vortex ratchet with a load.

We investigate experimentally a deterministic underdamped Josephson vortex ratchet-a fluxon particle moving along a Josephson junction in an asymmetric periodic potential. By applying a sinusoidal driving current, one can compel the vortex to move in a certain direction, producing an average dc voltage across the junction. Being in such a rectification regime, we also load the ratchet, i.

Demonstration of digital readout circuit for superconducting nanowire single photon detector.

We demonstrate the transfer of single photon triggered electrical pulses from a superconducting nanowire single photon detector (SNSPD) to a single flux quantum (SFQ) pulse. We describe design and test of a digital SFQ based SNSPD readout circuit and demonstrate its correct operation. Both circuits (SNSPD and SFQ) operate under the same cryogenic conditions and are directly connected by wire bonds.

Gold nanoantenna resonance diagnostics via transversal particle plasmon luminescence.

We perform two-photon excitation confocal experiments on coupled gold nanoantennas and observe time-integrated luminescence spectra that match plasmonic mode emission in the far-field. We show that the transversal particle plasmon mode can be excited, using excitation light that is cross-polarized with respect to the gold luminescence signal and therefore oriented along the long axis of the dipole gold antenna. We provide evidence for losses in polarization information from the excitation channel to the luminescence response due to the nature of the energy and momentum transfer.

Coupled nanoantenna plasmon resonance spectra from two-photon laser excitation.

We report on the two-photon excitation and subsequent plasmonic mode relaxation of coupled optical gold nanoantennas. Using pulsed laser excitation at a constant wavelength of 810 nm, we observe two-photon-induced plasmon emission spectra, find them to match dark-field microscopy scattering spectra, and show that the emission intensity is enhanced by up to a factor of 65 compared to single gold rods of equal dimensions. This study shows the link of nonlinear optical excitation schemes with radiative relaxation pathways that match plasmonic mode emission of resonant optical gold antennas.

Highly localized non-linear optical white-light response at nanorod ends from non-resonant excitation.

We investigate gold nanorods that are excited non-resonantly using a femtosecond 800 nm pulsed laser beam. We find that they emit very localized white light--two-photon induced photoluminescence (PL)--spatially confined in the optical far-field with a full-width-at-half-maximum of 138 nm (x-y plane) and 328 nm (z-plane). The PL spectrum is characterized to show at least two components--a second-harmonic peak and an intrinsic gold interband transition.

Nanoengineering and characterization of gold dipole nanoantennas with enhanced integrated scattering properties.

In this paper we present our approach for engineering gold dipole nanoantennas. Using electron-beam lithography we have been able to produce arrays of single gold antennas with dimensions from 70 to 300 nm total length with a highly reproducible nanoengineering protocol. Characterizing these gold nanoantenna architectures by optical means via dark-field microscopy and scattering spectroscopy gives the linear optical response function as a figure-of-merit for the antenna resonances, spectral linewidth and integrated scattering intensity.

Observation of negative absolute resistance in a Josephson junction.

We experimentally demonstrate the occurrence of negative absolute resistance (NAR) up to about -1 Omega in response to an externally applied dc current for a shunted Nb-Al/AlO_{x}-Nb Josephson junction, exposed to a microwave current at frequencies in the GHz range. The realization (or not) of NAR depends crucially on the amplitude of the applied microwave current. Theoretically, the system is described by means of the resistively and capacitively shunted junction model in terms of a moderately damped, classical Brownian particle dynamics in a one-dimensional potential.

Human spontaneous laryngeal carcinoma HEp-2 cells are chronically infected with SRV-1 virus, a variant of simian type D retrovirus.

A type D retrovirus chronically persisting in HEp-2 cells from human laryngeal carcinoma was analyzed by PCR and sequenced. This virus is most similar to SRV-1 and probably represents one of its subtypes.

[Detection of markers of the human T-cell leukemia virus in patients with T-cell lymphoma and Kaposi's sarcoma].

Nine patients with Kaposi's sarcoma and five suffering from T-cell lymphoma have been examined. Antibodies to HTLV-1 were not found in these patients. The primary cellular cultures were isolated from blood and lymph nodes of the patients.

[The regional use of antibiotics in treating craniocerebral trauma and suppurative complications].

The authors used the intracarotid and subarachnoid methods of infusion of antibiotics for treatment of purulent meningitis, brain abscesses. The methods are considered to be fairly effective.

[Antinuclear, anticentromere and anti-ScL-70 antibodies in rheumatic diseases].

Methods are described that are used for the titration of antinuclear, anticentromere, and anti-Scl-70 antibodies in systemic scleroderma, systemic lupus erythematosus, and rheumatoid arthritis: indirect immunofluorescence with various antigenic substrates (sections of fresh-frozen rat liver and Hep-2 cell culture), counter-current immunoelectrophoresis, isolation of Scl-70 antigen. Use of Hep-2 cells as a substrate for indirect immunofluorescence was found clinically and diagnostically more effective since it permitted the detection of anticentromere antibodies and anti-Scl-70. Nucleolar, mottled, homogeneous, marginal immunofluorescence types were observed when rat liver sections and Hep-2 cells were used for substrates.

[Antibodies to the structural and nonstructural gag-coded proteins of type-D retroviruses in patients with lymphadenopathy].

Screening of antibodies to structural and nonstructural gag gene-coded proteins in humans with lymphadenopathy and AIDS was performed by means of radioimmunoprecipitation (RIP) and western blotting. Pr78gag precursor of gag-coded proteins of type-D retrovirus from Hep-2 cells served as an antigen in RIP tests. Total number of sera (of humans with lymphoadenopathy) under RIP analysis was 18 and one sera of AIDS patient.

[Antibodies against structural proteins of carlaviruses in human and other mammals].

The study of four isolates of chrysanthemum B-virus (CVB) has shown the virus to have a single 40 Kd structural protein able to dissociate under the definite conditions forming the truncated (for 3 and 6 Kd) polypeptides having preserved their whole antigenic determinants. The human plasma is shown to contain antibodies reacting with the structural protein B-BX and, approximately 10 times weaker with the structural protein of another carlavirus, potato M-virus. Interaction of antibodies with CVB is found to take place due to F(ab)2 fragments.