A controllable superconducting inductor circuit comprises: a plurality of sub-circuits, each sub-circuit comprising: an inductor element; and a control element coupled to the inductor element to induce current in the inductor element in response to a control signal received at the control element. The inductor elements from the plurality of sub-circuits are arranged in parallel between a first pair of nodes to provide a tunable total inductance L.sub.tun. For each of the plurality of sub-circuits, the inductor element behaves as a superconducting kinetic inductance element when the current induced therein is less than a threshold level and behaves as a normal, non-superconducting inductor when the current induced therein is greater than the threshold level.

An electric circuit includes a plurality of superconducting components, each of the plurality of superconducting components having: a respective first terminal; a respective second terminal; and a respective input. The electric circuit further includes 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 bias current adapted to cause the electric circuit to function as a logical OR gate on the respective inputs of the plurality of superconducting components. The electric circuit further includes an output node adapted to output a state of the logical OR gate.

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 various embodiments described herein include methods, devices, and systems for fabricating and operating transistors. In one aspect, a transistor includes: (1) a semiconducting component configured to operate in an on state at temperatures above a semiconducting threshold temperature; and (2) a superconducting component configured to operate in a superconducting state while: (a) a temperature of the superconducting component is below a superconducting threshold temperature; and (b) a first current supplied to the superconducting component is below a current threshold; where: (i) the semiconducting component is located adjacent to the superconducting component; and (ii) in response to a first input voltage, the semiconducting component is configured to generate an electromagnetic field sufficient to lower the current threshold such that the first current exceeds the lowered current threshold, thereby transitioning the superconducting component to a non-superconducting state.

The various embodiments described herein include methods, devices, and systems for fabricating and operating transistors. In one aspect, a transistor includes: (1) a semiconducting component configured to operate in an on state at temperatures above a semiconducting threshold temperature; and (2) a superconducting component configured to operate in a superconducting state while: (a) a temperature of the superconducting component is below a superconducting threshold temperature; and (b) a first current supplied to the superconducting component is below a current threshold; where: (i) the semiconducting component is located adjacent to the superconducting component; and (ii) in response to a first input voltage, the semiconducting component is configured to generate an electromagnetic field sufficient to lower the current threshold such that the first current exceeds the lowered current threshold, thereby transitioning the superconducting component to a non-superconducting state.

An electronic component having an asymmetric impedance is provided. The component includes first, second and third branches that connect at a common node. The component includes a first portion of superconducting material disposed along the first branch and a second portion of superconducting material disposed along the second branch. The component includes a first device disposed along the first branch and configured to transition the second portion of the superconducting material to a non-superconducting state when a current between a first terminal of the first device and a second terminal of the first device exceeds a first threshold value and a second device disposed along the second branch and configured to transition the first portion of the superconducting material to a non-superconducting state when a current between a first terminal of the second device and a second terminal of the second device exceeds a second threshold value.

A transistor includes (i) a first wire including a semiconducting component configured to operate in an on state at temperatures above a semiconducting threshold temperature and (ii) a second wire including a superconducting component configured to operate in a superconducting state while: a temperature of the superconducting component is below a superconducting threshold temperature and a first input current supplied to the superconducting component is below a current threshold. The semiconducting component is located adjacent to the superconducting component. In response to a first input voltage, the semiconducting component is configured to generate an electromagnetic field sufficient to lower the current threshold such that the first input current exceeds the lowered current threshold.

According to an embodiment, a superconducting wire includes a substrate, an intermediate layer formed on the substrate, a superconducting layer formed on the intermediate layer, and a protective layer formed on the superconducting layer. The superconducting layer has a first portion, a second portion, and a third portion between the first portion and the second portion in the longitudinal direction of the superconducting wire. The protective layer on the third portion is at least partially removed.

A bistable device allows supercurrent to flow when functioning in one regime, wherein magnetization directions of different magnetic layers are antiparallel, but restricts supercurrent when switched to function in a resistive regime, wherein the magnetization directions are parallel. In the first regime, the device acts as a Josephson junction, which allows it to be used in superconducting quantum interference devices (SQUIDs) and other circuits in which quantization of magnetic flux in a superconducting loop is desired. In the second, resistive regime, flux quantization is effectively eliminated in loops containing the device, and current is diverted to parallel superconducting components. The bistable device thereby acts as a superconducting switch, useful for a variety of circuit applications, including to steer current for memory or logic circuits, adjust logical circuit functionality at runtime, or to burn off stray flux during cooldown.

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.