Methods of forming semiconductor-superconductor hybrid devices with a horizontally-confined channel are described. An example method includes forming a first isolated semiconductor heterostructure and a second isolated semiconductor heterostructure. The method further includes forming a left gate adjacent to a first side of each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure. The method further includes forming a right gate adjacent to a second side, opposite to the first side, of each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure, where a top surface of each of the left gate and the right gate is offset vertically from a selected surface of each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure by a predetermined offset amount. The method further includes forming a superconducting layer over each of the first isolated semiconductor heterostructure and the second isolated semiconductor heterostructure.

A superconducting circuit and a quantum computer capable of implementing four-body interaction using a plurality of superconducting qubit circuits supplied with signals of the same frequency are provided. A superconducting circuit (1) includes four superconducting qubit circuits (10), a coupling circuit (20) directly connected to the four superconducting qubit circuits (10). Each of the superconducting qubit circuits (10) indicates a qubit by being in a first phase state or a second phase state, when the number of the superconducting qubit circuits (10) in the first phase state among the four superconducting qubit circuits (10) is an even number, an interaction term of Hamiltonian of the superconducting circuit (1) takes a first value, and when the number of the superconducting qubit circuits (10) in the first phase state among the four superconducting qubit circuits (10) is an odd number, the interaction term takes a second value.

A method of fabricating semiconductor-superconductor nanowires, comprising: forming a first mask amorphous mask having first openings over trenches in a substrate; forming a monocrystalline conducting material in the first openings by selective area growth, thus forming gates for the nanowires in the trenches pf the substrate; forming a second mask over the substrate and gates, the second mask also being amorphous and having a pattern of second openings; forming an insulating crystalline buffer in the second openings; forming a crystalline semiconductor material on the buffer in the second openings by selective area growth in order to form the cores of the nanowires, wherein the gates intersect with the cores in the plane of the substrate; and forming the coating of superconductor material over at least part of each of the cores.

A method of fabricating semiconductor-superconductor nanowires, comprising: forming a first mask amorphous mask having first openings over trenches in a substrate; forming a monocrystalline conducting material in the first openings by selective area growth, thus forming gates for the nanowires in the trenches pf the substrate; forming a second mask over the substrate and gates, the second mask also being amorphous and having a pattern of second openings; forming an insulating crystalline buffer in the second openings; forming a crystalline semiconductor material on the buffer in the second openings by selective area growth in order to form the cores of the nanowires, wherein the gates intersect with the cores in the plane of the substrate; and forming the coating of superconductor material over at least part of each of the cores.

One aspect provides semiconductor-superconductor hybrid device comprises a substrate, a first semiconductor component arranged on the substrate, a superconductor component arranged to be capable of energy level hybridisation with the first semiconductor component, and a second semiconductor component arranged as a gate electrode for gating the first semiconductor component. Another aspect provides a semiconductor-superconductor hybrid device, comprising: a substrate; a semiconductor component arranged on the substrate; a gate electrode for gating the semiconductor component; and a superconductor component capable of undergoing energy level hybridisation with the semiconductor component; wherein the gate electrode is arranged in a channel in the substrate. Also provided are methods of fabricating the semiconductor-superconductor hybrid devices.

One aspect provides semiconductor-superconductor hybrid device comprises a substrate, a first semiconductor component arranged on the substrate, a superconductor component arranged to be capable of energy level hybridisation with the first semiconductor component, and a second semiconductor component arranged as a gate electrode for gating the first semiconductor component. Another aspect provides a semiconductor-superconductor hybrid device, comprising: a substrate; a semiconductor component arranged on the substrate; a gate electrode for gating the semiconductor component; and a superconductor component capable of undergoing energy level hybridisation with the semiconductor component; wherein the gate electrode is arranged in a channel in the substrate. Also provided are methods of fabricating the semiconductor-superconductor hybrid devices.

Methods related to the treatment of a quantum computing device to increase channel mobility are described. An example method includes forming a superconducting metal layer on a surface of a wafer. The method further includes selectively removing a portion of the superconducting metal layer to allow a subsequent formation of a gate dielectric associated with the device, where the selectively removing causes a decrease in channel mobility associated with the quantum computing device. The method further includes prior to forming the gate dielectric, subjecting the wafer to a plasma treatment, where a set of parameters associated with the plasma treatment is selected to increase the channel mobility.

A circuit can include a first sub-circuit, a second sub-circuit, and a third sub-circuit. The first sub-circuit can store a reset state or a set state, and can include a first Josephson junction (JJ), a second JJ, and a third JJ coupled in parallel using superconducting inductors. The first JJ, the second JJ, and the third JJ can be biased using a JJ-based current source. The second sub-circuit can switch the first sub-circuit to the set state in response to receiving a pulse. The third sub-circuit can switch the first sub-circuit to the reset state in response to receiving one or more pulses.

A gated Josephson junction includes a substrate and a vertical Josephson junction formed on the substrate and extending substantially normal the substrate. The vertical Josephson junction includes a first superconducting layer, a semiconducting layer, and a second superconducting layer. The first superconducting layer, the semiconducting layer, and the second superconducting layer form a stack that is substantially perpendicular to the substrate. The gated Josephson junction includes a gate dielectric layer in contact with the first superconducting layer, the semiconducting layer, and the second superconducting layer at opposing side surfaces of the vertical Josephson junction, and a gate electrically conducting layer in contact with the gate dielectric layer. The gate electrically conducting layer is separated from the vertical Josephson junction by the gate dielectric layer. In operation, a voltage applied to the gate electrically conducting layer modulates a current through the semiconducting layer of the vertical Josephson junction.

Technologies for radiofrequency optimized interconnects for a quantum processor are disclosed. In the illustrative embodiment, signals are carried in coplanar waveguides on a surface of a quantum processor die. A ground ring surrounds the signals and is connected to the ground conductors of each coplanar waveguide. Wire bonds connect the ground ring to a ground of a circuit board. The wire bonds provide both an electrical connection from the quantum processor die to the circuit board as well as increased thermal coupling between the quantum processor die and the circuit board, increasing cooling of the quantum processor die.