According to various implementations of the invention, a vertical Josephson Junction device may be realized using molecular beam epitaxy (MBE) growth of YBCO and PBCO epitaxial layers in an a-axis crystal orientation. Various implementations of the invention provide improved vertical JJ devices using SiC or LSGO substrates; GaN, AlN, or MgO buffer layers; YBCO or LSGO template layers; YBCO conductive layers and various combinations of barrier layers that include PBCO, NBCO, and DBCO. Such JJ devices are simple to fabricate with wet and dry etching, and allow for superior current flow across the barrier layers.

A superconducting article includes a substrate and a superconducting metal oxide film formed on the substrate. The metal oxide film including ions of an alkali metal, ions of a transition metal, and ions of an alkaline earth metal or a rare earth metal. For instance, the metal oxide film can include Rb ions, La ions, and Cu ions. The superconducting metal oxide film can have a critical temperature for onset of superconductivity of greater than 250 K, e.g., greater than room temperature.

Techniques for forming quantum circuits, including connections between components of quantum circuits, are presented. A trench can be formed in a dielectric material, by removing a portion of the dielectric material and a portion of conductive material layered on top of the dielectric material, to enable creation of circuit components of a circuit. The trench can define a regular nub or compensated nub to facilitate creating electrical leads connected to the circuit components on a nub. The compensated nub can comprise recessed regions to facilitate depositing material during evaporation to form the leads. For compensated nub implementation, material can be evaporated in two directions, with oxidation performed in between such evaporations, to contact leads and form a Josephson junction. For regular nub implementation, material can be evaporated in four directions, with oxidation performed in between the third and fourth evaporations, to contact leads and form a Josephson junction.

Techniques for forming quantum circuits, including connections between components of quantum circuits, are presented. A trench can be formed in a dielectric material, by removing a portion of the dielectric material and a portion of conductive material layered on top of the dielectric material, to enable creation of circuit components of a circuit. The trench can define a regular nub or compensated nub to facilitate creating electrical leads connected to the circuit components on a nub. The compensated nub can comprise recessed regions to facilitate depositing material during evaporation to form the leads. For compensated nub implementation, material can be evaporated in two directions, with oxidation performed in between such evaporations, to contact leads and form a Josephson junction. For regular nub implementation, material can be evaporated in four directions, with oxidation performed in between the third and fourth evaporations, to contact leads and form a Josephson junction.

The present disclosure relates to semiconductor based Josephson junctions and their applications within the field of quantum computing, in particular a tuneable Josephson junction device has been used to construct a gateable transmon qubit. One embodiment relates to a Josephson junction comprising an elongated hybrid nanostructure comprising superconductor and semiconductor materials and a weak link, wherein the weak link is formed by a semiconductor segment of the elongated hybrid nanostructure wherein the superconductor material has been removed to provide a semiconductor weak link.

The present invention is in the field of processes for the production of high temperature super-conductor wires. In particular, the present invention relates to a process for the production of high temperature superconductor wires comprising heating a film comprising yttrium or a rare earth metal, an alkaline earth metal, and a transition metal to a temperature of at least 700 C. and cooling the film to a temperature below 300 C., wherein the heating and cooling is per-formed at least twice.

Provided is a method of forming a superconducting wire, the method including forming a superconducting precursor film on a substrate, the super conducting precursor film containing Re, Ba, and Cu having a composition in which Ba is poor and Cu is rich compared to stoichiometric ReBCO(Gd.sub.1Ba.sub.2Cu.sub.3O.sub.7y, 0y6, Re: Rare earth element), heating the substrate to melt the superconducting precursor film, providing an oxygen gas having an oxygen partial pressure of about 10 mTorr to about 200 mTorr on the molten superconducting precursor film to form a superconducting layer including an epitaxial superconductor biaxially aligned only in the c-axis direction perpendicular to the substrate, and cooling the substrate.

A system and method for treating a cavity comprises arranging a niobium structure in a coating chamber, the coating chamber being arranged inside a furnace, coating the niobium structure with tin thereby forming an Nb.sub.3Sn layer on the niobium structure, and doping the Nb.sub.3Sn layer with nitrogen, thereby forming a nitrogen doped Nb.sub.3Sn layer on the niobium structure.

Techniques for forming quantum circuits, including connections between components of quantum circuits, are presented. A trench can be formed in a dielectric material, by removing a portion of the dielectric material and a portion of conductive material layered on top of the dielectric material, to enable creation of circuit components of a circuit. The trench can define a regular nub or compensated nub to facilitate creating electrical leads connected to the circuit components on a nub. The compensated nub can comprise recessed regions to facilitate depositing material during evaporation to form the leads. For compensated nub implementation, material can be evaporated in two directions, with oxidation performed in between such evaporations, to contact leads and form a Josephson junction. For regular nub implementation, material can be evaporated in four directions, with oxidation performed in between the third and fourth evaporations, to contact leads and form a Josephson junction.

According to various implementations of the invention, a vertical Josephson Junction device may be realized using molecular beam epitaxy (MBE) growth of YBCO and PBCO epitaxial layers in an a-axis crystal orientation. Various implementations of the invention provide improved vertical JJ devices using SiC or LSGO substrates; GaN, AlN, or MgO buffer layers; YBCO or LSGO template layers; YBCO conductive layers and various combinations of barrier layers that include PBCO, NBCO, and DBCO. Such JJ devices are simple to fabricate with wet and dry etching, and allow for superior current flow across the barrier layers.