The various embodiments described herein include methods, devices, and systems for fabricating and operating niobium-germanium-based superconducting devices. In one aspect, a device includes a superconducting nanowire composed of niobium-germanium, a protective layer configured to inhibit oxidation of the superconducting nanowire, and a current source configured to supply a current to the superconducting nanowire. In another aspect, a method of fabrication includes: (1) depositing a layer of niobium-germanium on a substrate; (2) removing one or more portions of the layer of niobium-germanium to define one or more nanowires; and (3) depositing a protective layer over the one or more nanowires, the protective layer adapted to inhibit oxidation of niobium-germanium in the one or more nanowires.

The various embodiments described herein include methods, devices, and systems for fabricating and operating niobium-germanium-based superconducting devices. In one aspect, a device includes a superconducting nanowire composed of niobium-germanium, a protective layer configured to inhibit oxidation of the superconducting nanowire, and a current source configured to supply a current to the superconducting nanowire. In another aspect, a method of fabrication includes: (1) depositing a layer of niobium-germanium on a substrate; (2) removing one or more portions of the layer of niobium-germanium to define one or more nanowires; and (3) depositing a protective layer over the one or more nanowires, the protective layer adapted to inhibit oxidation of niobium-germanium in the one or more nanowires.

A superconducting thermal detector (bolometer) of THz (sub-millimeter) wave radiation based on sensing the change in the amplitude or phase of a resonator circuit, consisting of a capacitor (Csh) and a superconducting temperature dependent inductor where the said inductor is thermally isolated from the heat bath (chip substrate) by micro-suspensions. The bolometer design includes a thin film inductor located on the membrane, a single or/and multi-layered thin film capacitor, and a thin film absorber of incoming radiation. The bolometer design can also include a lithographic antenna with antenna termination and/or a back reflector beneath the membrane for optimal wavelength detection by the resonance circuit. The superconducting thermal detector (bolometer) and arrays of these detectors operate in a temperature range from 1 Kelvin to 10 Kelvin.

The present invention discloses the low-stress niobium nitride (NbN) superconducting thin film and preparation method and application thereof. The preparation method includes the following steps: providing the metal Nb target and the Si-based substrates, fixing the Si-based substrate at room temperature, adjusting the mass flow ratio of N.sub.2/Ar to 20%-50%, the sputtering power to 50-400 W and the deposition pressure to 3.0-10.0 mTorr, NbN superconducting thin films with a stress range of-500 MPa?500 MPa and a thickness of 70-150 nm were deposited on Si-based substrates. By synergistically controlling the mass flow rate ratio of N.sub.2/Ar, sputtering power, and deposition pressure, low stress NbN superconducting thin films can be easily and efficiently prepared. The stress range of the prepared NbN superconducting thin films meets the preparation requirements of superconducting dynamic inductance detectors, and can be mass-produced.

Provided is a superconducting transition-edge thermal sensor, comprising a superconducting film defining an active area for incidence of quanta thereon, wherein the superconducting film is made of a superconductor exhibiting a charge carrier density below 10.sup.13 cm.sup.?2 and an electronic heat capacity below 10.sup.3 kb at the critical temperature Tc of said superconductor, wherein the superconductor is formed by two or more layers of two-dimensional crystals stacked on top of another.

A bolometer is described. A bolometer includes a superconductor-insulator-semiconductor-superconductor structure or a superconductor-insulator-semiconductor-insulator-superconductor structure. The semiconductor comprises an electron gas in a layer of silicon, germanium or silicon-germanium alloy in which valley degeneracy is at least partially lifted. The insulator or a one or both of the insulators may comprise a layer of dielectric material. The insulator or a one or both of the insulators may comprise a layer of non-degenerately doped semiconductor.

A method and a device for reducing the extrinsic dark count of a superconducting nanowire single photon detector (SNSPD), it comprises the steps of: integrating a multi-layer film filter on the superconducting nanowire single photon detector; the multi-layer film filter is a device implemented by a multi-layer dielectric film and having a band-pass filtering function. The extrinsic dark count is the dark count triggered by optical fiber blackbody radiance and external stray light. The superconducting nanowire single photon detector comprises: a substrate having an upper surface integrated with an upper anti-reflection layer and a lower surface integrated with a lower anti-reflection layer; an optical cavity structure; a superconducting nanowire; and a reflector. The present invention is easy to operate, and only needs to integrate the multi-layer film filter on the substrate of the SNSPD to filter non-signal radiation.

Disclosed in the present invention is a terahertz kinetic inductance bolometer, including a superconducting thin film layer, a terahertz antenna, a cutoff layer and a Si substrate, wherein the superconducting thin film layer and the terahertz antenna are respectively deposited on the cutoff layer, and the cutoff layer is deposited on the Si substrate; the superconducting thin film layer includes a superconducting feeder line, an inter-digital capacitor and an inductor coil; the inter-digital capacitor is connected with the inductor coil in parallel to form an oscillation circuit; the terahertz antenna is adjacent to the inductor coil and is used to convert a received terahertz signal into heat so that the inductor coil produces an inductance change; a resonance frequency in the inter-digital capacitor changes through the inductance change; and the superconducting feeder line receives the varying resonance frequency, through which an light intensity of the terahertz signal can be obtained to complete the detection of the terahertz signal. The terahertz kinetic inductance bolometer can detect the terahertz signal accurately and is less affected by the temperature. The present invention also provides a preparation method of the terahertz kinetic inductance bolometer and a terahertz detection system.

According to various embodiments, a quantum-engineered superconductor metamaterial is formed with a plurality of structurally engineered superconductor nanophononic crystal nanostructures. Each superconductor nanophononic crystal nanostructure may be formed as a crystal of the superconductor material. Structural modifications are made to each superconductor nanophononic crystal nanostructure to alter a characteristic of a phonon mode of the superconducting material to enhance a superconducting parameter thereof.

A superconducting electronic signal output circuit includes a signal source section configured to provide a voltage and/or current signal. The signal source section comprises a superconducting nanowire single photon detector, SNSPD, a switchable output section connected to the signal source section and having a first superconducting switch configured to selectably cause the signal to be output to an output of the superconducting electronic signal output circuit, and a switchable sink section connected to the signal source section and the switchable output section and having a second superconducting switch configured to selectably cause the signal to be directed to a reference potential.