Disclosed is a neuron circuit which electronically applies the working principle of the neurons in the human brain. The neuron circuit controls an input signal according to a set threshold value, and enables provision of an output signal above the threshold value.

A capacitively-driven tunable coupler includes a coupling capacitor connecting an open end of a quantum object (i.e., an end of the object that cannot have a DC path to a low-voltage rail, such as a ground node, without breaking the functionality of the object) to an RF SQUID having a Josephson element capable of providing variable inductance and therefore variable coupling to another quantum object.

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.

Techniques regarding a DSFQ logic family are provided. For example, one or more embodiments described herein can comprise a system, which can comprise a dynamic single flux quantum logic circuit that has a self-resetting internal state and can be powered by direct current. Further, the self-resetting internal state can be characterized by two time constants.

A method of operating a quantum information processing apparatus is provided. This apparatus includes a structure of coupled qubits, where N3, wherein the structure further includes coupling elements. The coupling elements couple pairs of N qubits, wherein, at least, a portion of the qubits are connected by a respective one of the coupling elements, whereby the two qubits of each said pair are connected by a respective coupling element. A method comprises identifying a path of M qubits in the structure of coupled qubits, wherein the path extends from a first qubit to a last qubit of the N qubits. The identified path consists of M qubits and M1 coupling elements alternating along said path, where 2<MN. A single-cycle operation is performed, wherein all pairs of two successive qubits in the identified path are concomitantly subjected to exchange-type interactions of distinct strengths.

There is described a microwave device and methods of operating same. The device comprises at least one superconducting qubit coupled to a transmission line defining a first port, and a filter. The filter comprises a first resonant element having a first resonance frequency f.sub.1, positioned along the transmission line between the first port and the qubit, and a second resonant element having a second resonance frequency f.sub.2 different from f.sub.1 and positioned along the transmission line between the first resonant element and the qubit.

A Josephson memory array and logic circuits use quasi-long-Josephson-junction interconnects to propagate signals at fast speeds and low energy expense, while permitting for memory arrays as dense fabrics of relatively simple unit cell sub-circuits, which include Josephson junctions, connected together by the interconnects. Each of the unit cell sub-circuits can be configured as a looped or linear arrangement. The unit cell sub-circuits and interconnects provide a fast, dense memory technology for reciprocal quantum logic (RQL), suitable for low-level caches and other memories collocated with an RQL processor.

A reciprocal quantum logic (RQL) wave-pipeline logic (WPL) inverting gate includes a Josephson junction-based comparator that corrects a design weakness present in other RQL WPL inverting gates that can lead to the propagation of glitches under certain timing conditions. With selective placement of pulse generators at the inputs, the RQL WPL inverting gate can be used to construct A AND (B XOR C) gates, XOR gates, NOT gates, and A-AND-NOT-B gates.

A superconducting distributed bidirectional current driver system includes multiple bidirectional current drivers, a bidirectional current load being operatively coupled between two adjacent bidirectional current drivers. Each of the bidirectional current drivers includes first and second superconducting latch circuits. The first superconducting latch circuit in a first one of the bidirectional current drivers and the second superconducting latch circuit in a second one of the bidirectional current drivers coupled to the current load are selectively activated by first and second activation signals, respectively, to establish a first current path through the current load in a first direction. The second superconducting latch circuit in the second one of the bidirectional current drivers and the first superconducting latch circuit in the first one of the bidirectional current drivers are selectively activated to establish a second current path through the current load in a second direction opposite the first direction.

A Josephson memory array and logic circuits use quasi-long-Josephson-junction interconnects to propagate signals at fast speeds and low energy expense, while permitting for memory arrays as dense fabrics of relatively simple unit cell sub-circuits, which include Josephson junctions, connected together by the interconnects. Each of the unit cell sub-circuits can be configured as a looped or linear arrangement. The unit cell sub-circuits and interconnects provide a fast, dense memory technology for reciprocal quantum logic (RQL), suitable for low-level caches and other memories collocated with an RQL processor.