The present invention relates to an inductive dipole element for a superconducting microwave quantum circuit. The dipole element comprises a DC-SQUID formed by a pair of Josephson junctions shunted by an inductance, wherein the Josephson junctions have equal energy, and the Josephson junctions and the inductance are arranged such that each of the junctions forms a loop with the inductance. The two loops are asymmetrically threaded with external magnetic DC fluxes φ.sub.ext1 and φ.sub.ext2, respectively, such that φ.sub.ext1=π and φ.sub.ext2=0, wherein parametric pumping is enabled by modulating the total flux φ.sub.Σ=φ.sub.ext,1+φ.sub.ext,2 threading the dipole element, thereby allowing even-wave mixing between modes that participate in the dipole element with no Kerr-like interactions.

Systems and techniques that facilitate quantum tuning via permanent magnetic flux elements are provided. In various embodiments, a system can comprise a qubit device. In various aspects, the system can further comprise a permanent magnet having a first magnetic flux, wherein an operational frequency of the qubit device is based on the first magnetic flux. In various instances, the system can further comprise an electromagnet having a second magnetic flux that tunes the first magnetic flux. In various cases, the permanent magnet can comprise a nanoparticle magnet. In various embodiments, the nanoparticle magnet can comprise manganese nanoparticles embedded in a silicon matrix. In various aspects, the system can further comprise an electrode that applies an electric current to the nanoparticle magnet in a presence of the second magnetic flux, thereby changing a strength of the first magnetic flux.

A configuration of wirebonds for reducing cross-talk in a quantum computing chip includes a first wirebond coupling a first conductor of a quantum computing circuit with a first conductor of an external circuit. The embodiment further includes in the configuration a second wirebond coupling a second conductor of the quantum computing circuit with a second conductor of the external circuit, wherein the first wirebond and the second wirebond are separated by a first vertical distance in a direction of a length of the first conductor.

Systems, computer-implemented methods, and techniques facilitating antenna-based thermal annealing of qubits are provided. In one example, a first antenna can be positioned above a superconducting qubit chip having a first Josephson junction and a second Josephson junction. The first antenna can direct a first electromagnetic wave toward the first Josephson junction. A first length of a first defined vertical gap, between the first antenna and the superconducting qubit chip, can be sized to cause the first electromagnetic wave to circumscribe a first set of one or more capacitor pads of the first Josephson junction, thereby annealing the first Josephson junction, without annealing the second Josephson junction. In another example, the first length of the first defined vertical gap can be a function of a model of the first electromagnetic wave as a cone, wherein the cone originates from the first antenna and extends toward the superconducting qubit chip.

Devices, systems, and/or methods that can facilitate local heating of a superconducting flux biasing loop are provided. According to an embodiment, a method can comprise forming on a substrate a biasing loop and a flux controlled qubit device of a superconducting flux bias circuit. The method can further comprise forming a heating device on the substrate to couple the heating device to the biasing loop.

A flux-biasing device includes a set of magnetic flux generating members. A first magnetic flux generating member is configured to magnetically interact with a first qubit from a set of qubits of a quantum processor such that a first magnetic flux of the first member causes a first change in a first resonance frequency of the first qubit by a first frequency shift value. Each non-corresponding magnetic flux generating member of the set is well separated from qubits corresponding to other magnetic flux generating members of the set such that qubits corresponding to other members exhibit less than a threshold value of resonance frequency shift as a result of a magnetic flux of a non-corresponding member.

A semiconductor-superconductor hybrid structure includes a semiconductor layer and a superconductor heterostructure on the semiconductor layer. The superconductor heterostructure includes a first superconductor layer on the semiconductor layer and a second superconductor layer on the first superconductor layer. The first superconductor layer comprises a first superconducting material and the second superconductor layer comprises a second superconducting material that is different from the first superconducting material. By providing the superconductor heterostructure as multiple layers of different superconducting materials, the superconducting and physical properties of the superconductor heterostructure can be improved compared to conventional superconducting homostructures, thereby increasing the performance of the semiconductor-superconductor hybrid structure.

A system and method are disclosed for a superconducting traveling-wave parametric amplifier (TWPA) with improved control and performance. In a preferred embodiment, the amplifier comprises an integrated array of symmetric rf-SQUIDs in a transmission line structure. A device was fabricated using niobium superconducting integrated circuits, and confirmed predicted performance, with a maximum gain up to 17 dB and a bandwidth of 4 GHz. A similar device can be applied as a low-noise, low-dissipation microwave amplifier for output from a superconducting quantum computer, or as a preamplifier, switch, or frequency converter for a sensitive microwave receiver, or as an output amplifier for a frequency-multiplexed superconducting detector array.

A quantum parameter amplifier; the quantum parameter amplifier includes a capacitor module, a first microwave resonant cavity, and an inductance-adjustable superconducting quantum interference apparatus that are connected in sequence to constitute an oscillation amplifier circuit, wherein, the superconducting quantum interference apparatus is grounded; the quantum parameter amplifier further includes a voltage modulating circuit and/or a second microwave resonant cavity; one end of the voltage modulating circuit is connected with an end of the superconducting quantum interference apparatus that is close to the first microwave resonant cavity; and one end of the second microwave resonant cavity is connected with the end of the superconducting quantum interference apparatus that is close to the first microwave resonant cavity. A frequency of a pump signal that makes the quantum parameter amplifier according to the present disclosure in an optimal operation mode does not need to be selected as a multiple of a frequency of the signal to be amplified.

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.