The invention is notably directed to a method of operating a superconducting channel. The method relies on a device including: a potentially superconducting material; a gate electrode; and an electrically insulating medium. A channel is defined by the potentially superconducting material. The gate electrode positioned adjacent to the channel, such that an end surface of the gate electrode faces a portion of the channel. The electrically insulating medium is arranged in such a manner that it electrically insulates the gate electrode from the channel. Rendering the channel superconducting by cooling down the device. Next, a voltage difference is applied between the gate electrode and the channel to inject electrons in the channel through the electrically insulating medium and thereby generate a gate current between the gate electrode and the channel. The electrons are injected with an average energy sufficient to modify a critical current I.sub.C of the channel.

A quantum computing devices includes: a qubit; a readout device coupled to the qubit, the readout device including a frequency filter having a filter frequency range; and an amplifier device coupled to the readout device, in which the amplifier device is configured to amplify a measurement signal from the readout device upon receiving a pump signal having a pump frequency that is outside of the filter frequency range of the frequency filter.

One example describes a superconducting XOR-gate system. The system includes a pulse generator configured to generate a decision pulse. The system also includes an input superconducting XOR-2 gate that receives a first superconducting logic input signal and a second superconducting logic input signal and is configured to perform a logic XOR function based on the decision pulse on a given phase of a clock signal to provide an intermediate superconducting logic output signal. The system also includes an output superconducting XOR-2 gate that receives the intermediate superconducting logic output signal and a third superconducting logic input signal and is configured to perform a logic XOR function based on the decision pulse on the given phase of the clock signal to provide a superconducting logic output signal.

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.

A device includes a plurality of superconducting components, each having a first terminal and a second terminal; a plurality of current sources, being electrically-connected to the first terminal of a corresponding superconducting component and configured to selectively provide a first current; and a bias current source electrically-connected to the respective first terminal of each of the plurality of superconducting components. The bias current source is configured to provide a second current adapted to bias the superconducting components such that (1) a combination of the second current and the first current from each current source causes the plurality of superconducting components to transition from the superconducting state to the non-superconducting state, and (2) a combination of the second current and the first current from each current source of only a subset of the plurality of current sources does not cause the plurality of superconducting components to transition to the non-superconducting state.

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.

The invention is notably directed to a method of operating a superconducting channel. The method relies on a device including: a potentially superconducting material; a gate electrode; and an electrically insulating medium. A channel is defined by the potentially superconducting material. The gate electrode positioned adjacent to the channel, such that an end surface of the gate electrode faces a portion of the channel. The electrically insulating medium is arranged in such a manner that it electrically insulates the gate electrode from the channel. Rendering the channel superconducting by cooling down the device. Next, a voltage difference is applied between the gate electrode and the channel to inject electrons in the channel through the electrically insulating medium and thereby generate a gate current between the gate electrode and the channel. The electrons are injected with an average energy sufficient to modify a critical current I.sub.C of the channel.

The present disclosure relates to improved electronic structures for propagating logic states between superconducting digital logic gates using a three-junction interferometer in a receiver circuit to reduce reflecting signals that otherwise result in distortions in the signals being transmitted between the gates. Other improved electronic structures comprise passive transmission lines (PTLs) with transmission line matching circuitry that has previously been avoided. The matching circuitry minimizes generation and propagation of spurious pulses emitted by Josephson junctions used in the digital logic gates.

An optical transmitter includes a superconducting driver circuit including at least one Josephson junction, the superconducting driver circuit having a voltage output and having a connection to a circuit ground, a first bias circuit coupled to the voltage output of the superconducting driver circuit, a second bias circuit, wherein the second bias circuit establishes a positive bias voltage relative to the circuit ground, and an electro-optic device having a first end and a second end, wherein the first end of the electro-optic device is coupled to the voltage output of the superconducting driver circuit, and wherein the second end of the electro-optic device is coupled to the second bias circuit.

A quantum computing devices includes: a qubit; a readout device coupled to the qubit, the readout device including a frequency filter having a filter frequency range; and an amplifier device coupled to the readout device, in which the amplifier device is configured to amplify a measurement signal from the readout device upon receiving a pump signal having a pump frequency that is outside of the filter frequency range of the frequency filter.