A system that includes: a qubit; a qubit readout resonator arranged adjacent to the qubit to couple to the qubit; and a first filter arranged adjacent to the qubit readout resonator to couple to the qubit readout resonator, the first filter comprising: a common port arranged to receive both a qubit readout resonator input drive signal and a measurement output signal from the qubit readout resonator, wherein the first filter is configured to impede at least one measurement photon emitted from the qubit is disclosed.

A system that includes: a qubit; a qubit readout resonator arranged adjacent to the qubit to couple to the qubit; and a first filter arranged adjacent to the qubit readout resonator to couple to the qubit readout resonator, the first filter comprising: a common port arranged to receive both a qubit readout resonator input drive signal and a measurement output signal from the qubit readout resonator, wherein the first filter is configured to impede at least one measurement photon emitted from the qubit is disclosed.

An apparatus and a method for indirectly cooling a superconducting quantum interference device (SQUID) are provided. The apparatus includes an outer container extending in a vertical direction; a metallic inner container inserted into the outer container to store a liquid coolant, the metal inner container including a top plate; a SQUID sensor module disposed between a bottom surface of the outer container and a bottom surface of the inner container; a heat transfer pillar adapted to cool the SQUID sensor module, the heat transfer pillar having one end connected to the bottom surface of the inner container and the other end directly or indirectly connected to the SQUID sensor module; a magnetic shield part formed of a superconductor covering a top surface of the SQUID sensor module; and a heat conduction plate being in thermal contact with the other end of the heat transfer pillar.

A connecting structure of an oxide superconducting wire includes a pair of oxide superconducting wires, tip surfaces of the pair of oxide superconducting wire being disposed to face to each other; a first surface-connecting superconducting wire configured to transit and connect the pair of oxide superconducting wires; and a second surface transit connector configured to transit and connect the pair of oxide superconducting wires, wherein tensile strength of joining sections between the second surface transit connector and the pair of oxide superconducting wires is higher than tensile strength of joining sections between the first surface-connecting superconducting wire and the pair of oxide superconducting wires.

An electronic device includes a pair of depletion gates, an accumulation gate, and a conductive resonator. The depletion gates are spaced apart from each other. The accumulation gate is over the depletion gates. The conductive resonator is over the depletion gates and the accumulation gate. The conductive resonator includes a first portion, a second portion, and a third portion. The first portion and the second portion are on opposite sides of the accumulation gate. The third portion interconnects the first and second portions of the conductive resonator and across the depletion gates. A bottom surface of the first portion of the conductive resonator is lower than a bottom surface of the accumulation gate.

A method of measuring contact resistance at an interface for superconducting circuits is provided. The method includes using a chain structure of superconductors to measure a contact resistance at a contact between contacting superconductor. The method further includes eliminating ohmic resistance from wire lengths in the chain structure by operating below the lowest superconducting transition temperature of all the superconductors in the chain structure. The measurement is dominated by contact resistances of the contacts between contacting superconductors in the chain.

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 interface between the cryogenic tubular filter assembly and room temperature electronics is achieved using hermetically sealed vacuum feed-through structures designed to receive flexible printed circuit board cable.

One embodiment includes a computer interconnect system. The system includes a first cable comprising a first superconducting signal line formed from a superconductor material to propagate at least one signal and a second cable comprising a second superconducting signal line formed from the superconductor material to propagate the respective at least one signal. The system also includes an interconnect structure configured to contact each of the first and second cable and comprising a third superconducting signal line formed from the superconductor material and configured to propagate the respective at least one signal between the respective first and second superconducting signal line. The system further includes at least one interconnect contact disposed on the first, second, and third at least one superconducting signal line at a contact portion between each of the at least one first and third superconducting signal lines and the at least second and third superconducting signal lines.

A quantum device (100) includes: an interposer (112); a quantum chip (111); a first connection part (130) that is provided between the interposer (112) and the quantum chip (111) and electrically connects a wiring layer of the interposer (112) to a wiring layer of the quantum chip (111); and a second connection part (140) that is provided on a main surface of the interposer (112) where the first connection part (130) is arranged and is connected to a cooling plate (115).

A quantum device (100) includes: an interposer (112); a quantum chip (111); and a connection part (130) that is provided between the interposer (112) and the quantum chip (111) and electrically connects a wiring layer of the interposer (112) to a wiring layer of the quantum chip (111), in which the connection part (130) includes: a plurality of pillars (131) arranged on a main surface of the interposer (112); and a metal film (132) provided on a surface of the plurality of pillars (131) in such a way that it contacts the wiring layer of the quantum chip (111) and the thickness of the metal film at outer peripheral parts of the tip of each of the plurality of pillars (131) becomes larger than the thickness of the metal film at a center part of the tip of each of the plurality of pillars (131).