The present invention relates to the manufacture of Josephson junctions. Such Josephson junctions may be suitable for use in qubits. High-quality, potentially monocrystalline, electrode and dielectric layers are formed using blanket deposition. Subsequently, the structure of one of more Josephson junctions is formed using multi-photon lithography to create openings in a resist followed by etching the electrode and dielectric layers.

It is an objective to provide an arrangement and a quantum computing system for qubit readout. According to an embodiment, an arrangement for qubit readout includes at least one qubit and a controllable energy relaxation structure comprising at least one junction. The controllable energy relaxation structure is coupled to the at least one qubit, and is configured to absorb, in response to a control signal, at least one photon from the at least one qubit via photon-assisted tunnelling of a charge through the at least one junction. The arrangement also includes a charge storage configured to store the tunnelled charge and a charge sensing structure coupled to the charge storage. The charge sensing structure is configured to provide a readout signal in response to detecting the tunnelled charge in the charge storage.

A device includes a first substrate formed of a first material that exhibits a threshold level of thermal conductivity. The threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum circuit operates. In an embodiment, the device also includes a second substrate disposed in a recess of the first substrate, the second substrate formed of a second material that exhibits a second threshold level of thermal conductivity. The second threshold level of thermal conductivity is achieved at a cryogenic temperature range in which a quantum circuit operates. In an embodiment, at least one qubit is disposed on the second substrate. In an embodiment, the device also includes a transmission line configured to carry a microwave signal between the first substrate and the second substrate.

A three-dimensional superconducting qubit and a method for manufacturing the same are disclosed. In an example, a three-dimensional superconducting qubit comprises a structural base comprising one or more insulating materials, and superconductive patterns on surfaces of the structural base. The superconductive patterns form at least a capacitive part and an inductive part of the three-dimensional superconducting qubit. A first surface of the surfaces of the structural base defines a first plane and a second surface of the surfaces of the structural base defines a second plane, the second plane being oriented differently than the first plane. At least one superconductive pattern of the superconductive patterns extends from the first surface to the second surface.

One example includes a magnetic Josephson junction (MJJ) system. The system includes a first superconducting material layer and a second superconducting material layer each configured respectively as a galvanic contacts. The system also includes a ferrimagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a fixed net magnetic moment at a predetermined operating temperature of the MJJ system. The system also includes a ferromagnetic material layer arranged between the first and second superconducting material layers and that is configured to exhibit a variable magnetic orientation in response to an applied magnetic field. The MJJ system can be configured to store a binary logical value based on a direction of the variable magnetic orientation of the ferromagnetic material layer. The system further includes a spacer layer arranged between the ferromagnetic and the ferrimagnetic material layers.

The disclosed technology is directed to systems and methods for deterministic reset of superconducting qubit and cavity modes with a microwave photon counter. The system comprises a multiplicity of qubit-microwave photon counter pairs coupled by a qubit-qubit coupling. Each of the qubit-microwave photon counter pairs comprise a qubit circuit, a microwave photon counter circuit, and a resonant cavity coupling the qubit circuit and the microwave photon counter circuit.

A circuit assembly for cooling a quantum electrical device, use of said circuit assembly, a system and a method for cooling a quantum electric device are provided. The circuit assembly comprises a quantum electric device to be cooled, at least one normal-metal-insulator-superconductor (NIS) tunnel junction electrically connected to the quantum electric device and at least one superconductive lead for supplying a drive voltage V.sub.QCR for said at least one NIS tunnel junction. The quantum electric device is cooled when the voltage V.sub.QCR is supplied to at least one NIS tunnel junction, said voltage V.sub.QCR being equal to or below the voltage NΔ/e, where N=1 or N=2, N is the number of NIS tunnel junctions electrically coupled in series with the means for generating the voltage, Δ is the energy gap in the superconductor density of states, and e is the elementary charge.

A tunable coupler for making a controllable coupling to at least a first qubit is disclosed. The tunable coupler includes a first constant coupling element and a tunable coupling element. The first constant coupling element forms a non-galvanic coupling interface to at least the first qubit at a first extremity that is distant from the tunable coupling element. The tunable coupling element is located adjacent to a non-galvanic coupling interface formed as an interface to a circuit element at a second extremity thereof.

Methods, apparatuses, and devices for Josephson junction preparation includes: obtaining a first pattern structure for generating a first Josephson junction of a first type and a plurality of second pattern structures for generating a plurality of second Josephson junctions of a second type; evaporating a material on the first pattern structure and the plurality of second pattern structures based on a first evaporation direction to generate a first electrode layer for implementing information transmission; forming an insulating layer on the first electrode layer, the insulating layer including a compound corresponding to the material; evaporating the material on the first pattern structure and the plurality of second pattern structures based on a second evaporation direction to generate a second electrode layer for implementing information transmission; and forming the first Josephson junction and the plurality of second Josephson junctions.

A circuit can include a galvanic coupling of a coupler to a qubit by a segment of kinetic inductance material. The circuit can include a galvanic kinetic inductance coupler having multiple windings. The circuit can include a partially-galvanic coupler having multiple windings. The partially-galvanic coupler can include a magnetic coupling and a galvanic coupling. The circuit can include an asymmetric partially-galvanic coupler having a galvanic coupling and a first magnetic coupling to one qubit and a second magnetic coupling to a second qubit. The circuit can include a compact kinetic inductance qubit having a qubit body loop comprising a kinetic inductance material. A multilayer integrated circuit including a kinetic inductance layer can form a galvanic kinetic inductance coupling. A multilayer integrated circuit including a kinetic inductance layer can form at least a portion of a compact kinetic inductance qubit body loop.