A reversible memory element is provided. The reversible memory element comprises a reversible memory cell comprising a Josephson junction and a passive inductor. A ballistic interconnect is connected to the reversible memory cell by a bidirectional input/output port. A polarized input fluxon propagating along the ballistic interconnect exchanges polarity with a stationary stored fluxon in the reversible memory cell in response to the input fluxon reflecting off the reversible memory cell.

Electrical, mechanical, computing, and/or other devices that include components formed of extremely low resistance (ELR) materials, including, but not limited to, modified ELR materials, layered ELR materials, and new ELR materials, are described.

A technique relates to a superconducting microwave combiner. A first filter through a last filter connects to a first input through a last input, respectively. The first filter through the last filter each has a first passband through a last passband, respectively, such that the first passband through the last passband are each different. A common output is connected to the first input through the last input via the first filter through the last filter.

A system and method of operation embeds a three-dimensional structure in a topology of an analog processor, for example a quantum processor. The analog processor may include a plurality of qubits arranged in tiles or cells. A number of qubits and communicatively coupled as logical qubits, each logical qubit which span across a plurality of tiles or cells of the qubits. Communicatively coupling between qubits of any given logical qubit can be implemented via application or assignment of a first ferromagnetic coupling strength to each of a number of couplers that communicatively couple the respective qubits in the logical qubit. Other ferromagnetic coupling strengths can be applied or assigned to couplers that communicatively couple qubits that are not part of the logical qubit. The first ferromagnetic coupling strength may be substantially higher than the other ferromagnetic coupling strengths.

Techniques for a vertical Josephson junction superconducting device using microstrip waveguides are provided. In one embodiment, a chip surface base device structure is provided that comprises a superconducting material located on a first side of a substrate, and a second superconducting material located on a second side of the substrate and stacked on a second substrate, wherein the first side of the substrate and the second side of the substrate are opposite sides. In one implementation, the substrate or the second substrate, or the substrate and the second substrate are crystalline silicon. In one implementation, the chip surface base device structure also comprises a transmon qubit comprising a capacitor and a Josephson junction formed in a via of the substrate and comprising a tunnel barrier. In one implementation, the chip surface base device structure also comprises a microstrip line electrically coupled to the transmon qubit.

A first aspect provides a topological quantum computing device comprising a network of semiconductor-superconductor nanowires, each nanowire comprising a length of semiconductor formed over a substrate and a coating of superconductor formed over at least part of the semiconductor; wherein at least some of the nanowires further comprise a coating of ferromagnetic insulator disposed over at least part of the semiconductor. A second aspect provides a method of fabricating a quantum or spintronic device comprising a heterostructure of semiconductor and ferromagnetic insulator, by: forming a portion of the semiconductor over a substrate in a first vacuum chamber, and growing a coating of the ferromagnetic insulator on the semiconductor by epitaxy in a second vacuum chamber connected to the first vacuum chamber by a vacuum tunnel, wherein the semiconductor comprises InAs and the ferromagnetic insulator comprises EuS.

A method of fabricating an electrical contact junction that allows current to flow includes: providing a substrate including a first layer of superconductor material; removing a native oxide of the superconductor material of the first layer from a first region of the first layer; forming a capping layer in contact with the first region of the first layer, in which the capping layer prevents reformation of the native oxide of the superconductor material in the first region; forming, after forming the capping layer, a second layer of superconductor material that electrically connects to the first region of the first layer of superconductor material to provide the electrical contact junction that allows current to flow.

According to an embodiment, a radiation detector includes a plurality of absorbers, a resistor, and a heat bath member. The absorbers absorb radiation. The resistor undergoes a change in resistance according to a change in temperature of the absorbers. The heat bath member is maintained at a temperature at which resistance of the resistor becomes equal to a specific resistance value, and is positioned to be in thermal contact with the resistor. The absorbers are positioned to be in contact with the resistor, and are arranged at a distance from each other.

A first aspect provides a topological quantum computing device comprising a network of semiconductor-superconductor nanowires, each nanowire comprising a length of semiconductor formed over a substrate and a coating of superconductor formed over at least part of the semiconductor; wherein at least some of the nanowires further comprise a coating of ferromagnetic insulator disposed over at least part of the semiconductor. A second aspect provides a method of fabricating a quantum or spintronic device comprising a heterostructure of semiconductor and ferromagnetic insulator, by: forming a portion of the semiconductor over a substrate in a first vacuum chamber, and growing a coating of the ferromagnetic insulator on the semiconductor by epitaxy in a second vacuum chamber connected to the first vacuum chamber by a vacuum tunnel, wherein the semiconductor comprises InAs and the ferromagnetic insulator comprises EuS.

A modular superconducting quantum processor includes a first superconducting chip including a first plurality of qubits each having substantially a first resonance frequency and a second plurality of qubits each having substantially a second resonance frequency, the first resonance frequency being different from the second resonance frequency, and a second superconducting chip including a third plurality of qubits each having substantially the first resonance frequency and a fourth plurality of qubits each having substantially the second resonance frequency. The quantum processor further includes an interposer chip connected to the first superconducting chip and to the second superconducting chip. The interposer chip has interposer coupler elements configured to couple the second plurality of qubits to the fourth plurality of qubits.