A second-generation high temperature superconducting (HTS) strip and a preparation method thereof are provided. The second-generation HTS strip includes a superconducting strip body and a stabilizing layer arranged thereon. The stabilizing layer is a copper-graphene composite film with a total thickness of 2-30 microns on one side. The superconducting strip may be obtained by the preparation method of: (1) putting a superconducting strip body into a magnetron sputtering reaction chamber, followed by pumping to a high-level vacuum and filling with a working gas; (2) using copper and graphene as targets, and performing a sputter coating by controlling a magnetron sputtering power, to deposit the targets onto at least one surface of the superconducting strip body. The prepared HTS strips containing copper-graphene stabilizing layer with high strength and high conductivity may have 30%-70% higher tensile strength than conventional copper plated superconducting strips, with less than 10% IACS attenuation in conductivity.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

The present invention provides a process and structure of microfabricated air bridges for planar microwave resonator circuits. In an embodiment, the invention includes depositing a superconducting film on a surface of a base material, where the superconducting film is formed with a compressive stress, where the compressive stress is higher than a critical buckling stress of a defined structure, etching an exposed area of the superconducting film, thereby creating the at least one bridge, etching the base material, thereby forming a gap between the at least one bridge and the base material, depositing the at least one metal line on at least part of the superconducting film and at least part of the base material, where the at least one metal line runs under the bridge.

Methods and apparatus are disclosed for cooling superconducting signal lines disposed on an interconnect such as a flexible cable or a rigid substrate. The superconducting signal lines are cooled to a cryogenic temperature lower than the temperature at which at least some superconducting logic devices coupled to the interconnect are operated. In some examples, an airtight conduit, heat pipe, or thermally conduct of strap provided to cool the superconducting interconnect. In one example of the disclosed technology, a system includes at least two sets of superconducting logic devices, cooling apparatus adapted to cool the logic devices to a first operating temperature, and interconnect coupling the superconducting logic devices, and a cooling apparatus in thermal communication with the interconnect. The apparatus is adapted to cool superconducting signal lines on the interconnect to a lower operating temperature than the first operating temperature at which the superconducting logic devices operate.

Methods and apparatus are disclosed for cooling superconducting signal lines disposed on an interconnect such as a flexible cable or a rigid substrate. The superconducting signal lines are cooled to a cryogenic temperature lower than the temperature at which at least some superconducting logic devices coupled to the interconnect are operated. In some examples, an airtight conduit, heat pipe, or thermally conduct of strap provided to cool the superconducting interconnect. In one example of the disclosed technology, a system includes at least two sets of superconducting logic devices, cooling apparatus adapted to cool the logic devices to a first operating temperature, and interconnect coupling the superconducting logic devices, and a cooling apparatus in thermal communication with the interconnect. The apparatus is adapted to cool superconducting signal lines on the interconnect to a lower operating temperature than the first operating temperature at which the superconducting logic devices operate.

A superconducting wire connector includes superconducting wires and a sintered body containing MgB.sub.2. The superconducting wires are connected by the sintered body. At least one of the superconducting wires includes a superconducting core having a first outer surface. The sintered body is in contact with the first outer surface. A method of connecting superconducting wires by a sintered body containing MgB.sub.2 includes exposing a superconducting core of at least one of the superconducting wires by removing a portion, positioned in the middle in a longitudinal direction of the at least one of the superconducting wires, of a metal sheath disposed around the superconducting core, disposing the at least one of the superconducting wires through a container, filling the container with a raw material of MgB.sub.2, and forming the sintered body being in contact with an outer surface of the superconducting core by sintering the raw material filled in the container.

A superconducting coil includes: a winding member 12 that has a side surface 18 along a coil radial direction and is formed by laminating a superconducting tape wire 20 in the coil radial direction by winding; and a bypass 19 that is provided on the side surface 18 of the winding member 12 and electrically connects the superconducting tape wire 20 in the coil radial direction.

Systems and devices for providing differential input/output communication with a superconducting device are described. Each differential I/O communication is electrically filtered using a respective tubular filter structure incorporating superconducting lumped element devices and high frequency dissipation by metal powder epoxy. A plurality of such tubular filter structures is arranged in a cryogenic, multi-tiered assembly further including structural/thermalization supports and a device sample holder assembly for securing a device sample, for example a superconducting quantum processor. The ace between the cryogenic tubular assembly and room temperature electronics is achieved using hermetically sealed vacuum feed-through structures designed to receive flexible printed circuit board cable.

An electronic device (e.g., a diode) is provided that includes a substrate and a patterned layer of superconducting material disposed over the substrate. The patterned layer forms a first electrode, a second electrode, and a loop coupling the first electrode with the second electrode by a first channel and a second channel. The first channel and the second channel have different minimum widths. The device further includes a magnet that applies a magnetic field to the loop, which produces an expulsion current in the loop that travels toward the second electrode in the first channel and toward the first electrode in the second channel. For a range of current magnitudes, when the magnetic field is applied to the patterned layer of superconducting material, the conductance from the first electrode to the second electrode is greater than the conductance from the second electrode to the first electrode.

Methods and apparatus are disclosed for cooling superconducting signal lines disposed on an interconnect such as a flexible cable or a rigid substrate. The superconducting signal lines are cooled to a cryogenic temperature lower than the temperature at which at least some superconducting logic devices coupled to the interconnect are operated. In some examples, an airtight conduit, heat pipe, or thermally conduct of strap provided to cool the superconducting interconnect. In one example of the disclosed technology, a system includes at least two sets of superconducting logic devices, cooling apparatus adapted to cool the logic devices to a first operating temperature, and interconnect coupling the superconducting logic devices, and a cooling apparatus in thermal communication with the interconnect. The apparatus is adapted to cool superconducting signal lines on the interconnect to a lower operating temperature than the first operating temperature at which the superconducting logic devices operate.