The disclosure relates to a quantum detector configured to receive a microwave signal from a microwave source. The quantum detector comprises a main element formed by a main Josephson junction and a Josephson transmission line which is coupled to the main element for outputting a measurement signal. The Josephson transmission line comprises at least a first set of JTL elements and a second set of JTL elements. The capacitively shunted Josephson junction in each JTL element in the first set is weakly damped, and the JTL element in the second set are more strongly damped than the JTL elements in the first set.

An electromechanical conversion device includes a resonant electrical circuit comprising an inductance and a capacitor, the capacitor including at least a first electrode and a second electrode; and a mechanical oscillator including at least one microbeam formed in a membrane, the first and second electrodes being located side by side and the first electrode of the capacitor being located on a face of the microbeam so that the electrical capacitance of the capacitor varies when the mechanical oscillator oscillates; device wherein the inductance includes an electric track of very low thickness made on the membrane and made of a superconductive material chosen so as to obtain an electric track with a high kinetic inductance.

An oscillator in which crosstalk can be reduced is provided. An oscillator includes a SQUID, a transmission line connected to the SQUID, a ground plane, and a first connection circuit disposed in a vicinity of a node of an electric field of a standing wave that is generated when the oscillator is oscillating, the first connection circuit connecting parts of the ground plane located on both sides of the transmission line to each other.

An oscillator includes a spin current source, and a free layer coupled to the spin current source. The free layer has a magnetization hard axis that is parallel to a quantization axis of a spin current injected by the spin Hall effect of the spin current source.

Superconducting Meissner effect transistors, methods of modulating, and systems are disclosed. In one aspect a disclosed transistor includes a superconducting bridge between a first and a second current probe, the first and second current probe being electrically connected to a source and a drain electrical connection, respectively and a control line configured to emit a magnetic field signal having signal strength H.sub.sig at the superconducting bridge. In one aspect the emitted magnetic field is configured to break Cooper pairs in the superconducting bridge.

A tunable oscillator including a Josephson junction. In some embodiments, the tunable oscillator includes a first superconducting terminal, a second superconducting terminal, a graphene channel including a portion of a graphene sheet, and a conductive gate. The first superconducting terminal, the second superconducting terminal, and the graphene channel together may form a Josephson junction having an oscillation frequency, and the conductive gate may be configured, upon application of a voltage across the conductive gate and the graphene channel, to modify the oscillation frequency.

An oscillator in which crosstalk can be reduced is provided. An oscillator includes a ground plane made of a superconductor, a conductive member spaced apart from and surrounded by the ground plane, a SQUID of which one end is connected to the conductive member and the other end is connected to the ground plane, a first connection circuit made of a superconductor, connecting parts of the ground plane located on both sides of a vicinity of a connection part between the conductive member and the SQUID to each other, and a superconducting loop circuit surrounding the SQUID and using the ground plane and the first connection circuit.

An oscillator in which crosstalk can be reduced is provided. An oscillator includes a SQUID, a transmission line connected to the SQUID, a ground plane, and a first connection circuit disposed in a vicinity of a node of an electric field of a standing wave that is generated when the oscillator is oscillating, the first connection circuit connecting parts of the ground plane located on both sides of the transmission line to each other.

A reservoir computer. In some embodiments, the reservoir computer includes a Duffing oscillator, and a readout circuit, and the readout circuit is configured to calculate a plurality of products, each of the products being calculated by multiplying a sample, of a plurality of samples of a signal from the Duffing oscillator, by a respective weight of a plurality of weights.

An oscillator in which crosstalk can be reduced is provided. An oscillator includes a SQUID, a transmission line connected to the SQUID, a ground plane, and a first connection circuit disposed in a vicinity of a node of an electric field of a standing wave that is generated when the oscillator is oscillating, the first connection circuit connecting parts of the ground plane located on both sides of the transmission line to each other.