Abstract: A quantum device is fabricated by forming a network of nanowires oriented in a plane of a substrate to produce a Majorana-based topological qubit. The nanowires are formed from combinations of selective-area-grown semiconductor material along with regions of a superconducting material. The selective-area-grown semiconductor material is grown by etching trenches to define the nanowires and depositing the semiconductor material in the trenches. A side gate is formed in an etched trench and situated to control a topological segment of the qubit.

Abstract: Compactly-integrated electronic structures and associated systems and methods are provided. Certain embodiments relate to the ability to integrate nanowire-based detectors with optical components.

Abstract: A superconducting nanowire single photon detector (SN-SPD) microelectronic circuit is described which has higher quantum efficiency and signal-to-noise than any SN-SPD's known in the art. The material and configuration of the microelectronic circuit eliminates the polarization dependence and shows improved signal-to-noise over SN-SPD microelectronic circuits known in the art. The higher efficiency, polarization independence, and high signal-to-noise is achieved by vertically stacking two tungsten-silicide (TS) SN-SPDs and electrically connecting them in parallel. This structure forms a multilayer superconducting nanowire avalanche photo-detector (SNAP). A single photon detection device employing the multilayer (SNAP) microelectronic circuit demonstrates a peak system detection efficiency of 87.7% and a polarization dependence of less than 2%. This represents nearly an order of magnitude improvement in both system detection efficiency and reduction of polarization dependence compared to conventional SNSPDs.

Abstract: Terahertz radiation source and method of producing terahertz radiation, said source comprising a junction stack, said junction stack comprising a crystalline material comprising a plurality of self-synchronized intrinsic Josephson junctions; an electrically conductive material in contact with two opposing sides of said crystalline material; and a substrate layer disposed upon at least a portion of both the crystalline material and the electrically-conductive material, wherein the crystalline material has a c-axis which is parallel to the substrate layer, and wherein the source emits at least 1 mW of power.

Abstract: An optical element is disclosed which includes transparent superconductor material.

Abstract: Systems, articles, and methods are provided related to nanowire-based detectors, which can be used for light detection in, for example, single-photon detectors. In one aspect, a variety of detectors are provided, for example one including an electrically superconductive nanowire or nanowires constructed and arranged to interact with photons to produce a detectable signal. In another aspect, fabrication methods are provided, including techniques to precisely reproduce patterns in subsequently formed layers of material using a relatively small number of fabrication steps. By precisely reproducing patterns in multiple material layers, one can form electrically insulating materials and electrically conductive materials in shapes such that incoming photons are redirected toward a nearby electrically superconductive materials (e.g., electrically superconductive nanowire(s)). For example, one or more resonance structures (e.g.

Abstract: Disclosed is a semiconductor light emitting device. The semiconductor light emitting device includes a plurality of compound semiconductor layers including a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; a dot type conductive layer on the compound semiconductor layers; and an electrode layer on the dot type conductive layer.

Abstract: A method and apparatus for modulating light, wherein a light source provides light of a certain wavelength to be modulated by a layer of superconducting material which forms part of a specifically configured plate assembly. The superconducting layer is placed in the optical path of the light source. Further the superconducting layer is switched between a partially transparent non-superconducting state and a substantially non-transparent superconducting state by a modulation circuit. The resulting optical pulses transmitted through the superconducting layer are converted from the original wavelength to a lower wavelength by a frequency converting device.

Abstract: A quantum cryptographic communication channel having: a light source; a reflector; first and second sources each capable of generating a pair of photons emitted in the form of signal and idler light beams when energized by the light source, the first and second sources being arranged relative to each other such that the idler beam from the first source is incident upon the second source and aligned into the idler beam of the second source and the signal beams are directed by the reflector to converge upon a common point; a light modulator for changing the phase of the idler beam from the first source between first and second phase settings before being incident upon the second source; a controller for controlling the timing of the phase change from the first phase setting to the second phase setting; first and second detectors for detecting the incidence of the signal beams from the first and second sources; and a beam splitter disposed at the common point for directing the signal beams to the first detector

Abstract: The present invention relates to a nitrogen oxide detecting element. Although there has been a demand for effecting detection of a nitrogen oxide by using a semiconductor type gas sensor, no semiconductor type sensors have existed which can detect the nitrogen oxide with good selectivity against other interfering gases (CO, H2) for an extended period of time with good durability. Then, by causing a gas detecting portion to include an oxide containing more than a predetermined amount of Bi and maintaining this gas detecting portion at a temperature range where its electron-conductivity is exhibited, it has become possible to detect the nitrogen oxide.

Abstract: A method and apparatus for modulating light, wherein a light source provides light of a certain wavelength to be modulated by a layer of superconducting material which forms part of a specifically configured plate assembly. The superconducting layer is placed in the optical path of the light source. Further the superconducting layer is switched between a partially transparent non-superconducting state and a substantially non-transparent superconducting state by a modulation circuit. The resulting optical pulses transmitted through the superconducting layer are converted from the original wavelength to a lower wavelength by a frequency converting device.

Abstract: An ultra high speed and high sensitivity photo detecting element is fabricated by laminating thin film layers of superconducting material and ferromagnetic material on a substrate. A photo detecting element composed of a photo detecting portion formed on a substrate by laminating alternately at least a thin film layer of ferromagnetic material and at least a thin film layer of high temperature superconducting material between which a thin film layer of insulating material is sandwiched and electrodes connected to the photo detecting portion.

Abstract: Superconducting device include a type having a structure of a superconductor--a normal-conductor (or a semiconductor)--a superconductor, and a type having a superconducting weak-link portion between superconductors.The superconductors constituting the superconducting device are made of an oxide of either of perovskite type and K.sub.2 NiF.sub.4 type crystalline structures, containing at least one element selected from the group consisting of Ba, Sr, Ca, Mg, and Ra; at least one element selected from the group consisting of La, Y, Ce, Sc, Sm, Eu, Er, Gd, Ho, Yb, Nd, Pr, Lu, and Tb; Cu; and O. In addition, the c-axis of the crystal of the superconductor is substantially perpendicular to the direction of current flowing through this superconductor.

Abstract: A thermoelectric radiation detector having a substrate (1) and a film (2) of solid state material having thermal anisotropy and containing YBa.sub.2 Cu.sub.3 O.sub.7, formed on the surface of the substrate, and wherein said film has CuO.sub.2 planes (3) inclined with respect to the substrate plane, the improvement wherein at least a portion of the Y is replaced by another rare earth metal and/or at least a portion of the Ba and/or of the Cu is replaced by at least one other heavy metal at least in partial areas of the film and in a sufficient amount to increase the thermal anisotropy of the detector.

Abstract: A method and apparatus for modulating light, wherein a light source provides light of a certain wavelength to be modulated by a layer of superconducting material which forms part of a specifically configured plate assembly. The superconducting layer is placed in the optical path of the light source. Further the superconducting layer is switched between a partially transparent non-superconducting state and a substantially non-transparent superconducting state by a modulation circuit. The resulting optical pulses transmitted through the superconducting layer are converted from the original wavelength to a lower wavelength by a frequency converting device.

Abstract: The substance has a composition of a general chemical formula ofBi.sub.2 -(Sr.sub.2 Ca.sub.1).sub.1-x (La.sub.2 Y.sub.1).sub.x -Cu.sub.y -O.sub.z,where 0.4.ltoreq.x.ltoreq.1, y=2 and z=9-10.5, wherein the substance is an insulator or a semiconductor in the dark, and has a photoconductivity Q(.lambda.,T) in conjugate with superconductivity of a superconductor of an adjacent component of the Bi-SrCa-LaY-Cu-O system at and below a critical temperature (T) of less than 105.degree.-115.degree. K. and below 65.degree.-85.degree. K. at photoexcitation in an optical wavelength range (.lambda.) of 420-670 nm. The present invention relates to a method for producing the same and a superconductive optoelectronic device by using the same. The present invention also relates to an organized integration of the element or device into an apparatus to further develop a new field of "Superconductive Optoelectronics.

Abstract: An optical data transmission system includes an optical data receiver having a plurality of optical detectors and an optical switch which directs successive pulses of a serial data stream to different detectors. The switch includes one or more superconductive mirrors responsive to current pulses to change from a superconducting, reflective state to a non-superconducting, non-reflective state for the duration of a current pulse. In this manner, high speed optical data is received by detectors incapable of operating at the high speed of available optical data links and transmitters. The mirror is oriented at an angle to the data stream such that an optical pulse is reflected to one detector when the mirror is in the superconducting, reflective state and is passed through the mirror to another detector when the mirror is temporarily in the non-superconducting, non-reflective state under the control of a current pulse.

Abstract: The disclosed oxide has a general chemical formula of Ca.sub.X-x)-Sr.sub.x -Bi.sub.(Y-y)-Cu.sub.y -O.sub.x X being 2 to 3, 0.ltoreq.x<1, Y being 3 to 4, 0<y.ltoreq.2, and z being 4 to 9, and the oxide shows, at a temperature below 105 to 115 K, both a photoconductivity and an either real or potential superconductivity, namely, "superconductive photoconductivity" in a wavelength range of 530 to 740 nm.The oxide is made by heating a mixture of starting materials for the above composition of Ca.sub.X-x -Sr.sub.x -Bi.sub.Y-y -Cu.sub.y -O.sub.z at 700.degree.-850.degree. C. for 2-10 hours so as to effect primary sintering for causing solid phase reactions in the mixture, cooling gradually, shaping under pressure, reheating the shaped materials at 750.degree.-880.degree. C. for 2-10 hours so as to effect secondary sintering thereon, cooling, keeping the reheated materials at 500.degree.-600.degree. C. for 2-3 hours and cooling the same either extremely quickly at a rate of 1500-900.degree. C.

Abstract: The disclosed oxide has a general chemical formula of Ba-Pb.sub.1-x -Bi.sub.x -O.sub.z, x being 0.35 to 1 and z being 2.7 to 3, and the oxide shows a potential superconductivity at a temperature below 14K and a photoconductivity at a temperatures below 160K at least in an exciting wavelength range of 500 to 700 nm depending on the value of the above x.The oxide is made by heating a mixture of starting materials for the desired composition at 750-850.degree. C. for 2-10 hours so as to cause solid phase reaction in the mixture, cooling the heated materials gradually, shaping the cooled mixture under pressure, reheating the shaped materials at 500-850.degree. C. for 2-10 hours so as to effect secondary sintering thereon, keeping the reheated materials at 600-500.degree. C. for 2-3 hours and cooling the same either extremely quickly at a rate of 1500-900.degree. C./sec or slowly at a rate of 150-200.degree. C./hour.

Abstract: A superconducting tunnel element, having a plurality of super conductors separated by barriers, the superconductors each comprising two physically separate but electrically connected superconducting layers and one insulated control layer. As a result, summation of the detection capacity or of the transmitting intensity becomes possible. Also, the simultaneous detection or transmission is permitted on arbitrary different frequencies or a summation of the signal intensity is possible in the case of SQUID-systems.