In various embodiments, superconducting wires incorporate diffusion barriers composed of Nb alloys or NbTa alloys that resist internal diffusion and provide superior mechanical strength to the wires.

In various embodiments, superconducting wires feature assemblies of clad composite filaments and/or stabilized composite filaments embedded within a wire matrix. The wires may include one or more stabilizing elements for improved mechanical properties.

Disclosed herein are quantum dot devices, as well as related computing devices and methods. For example, in some embodiments, a quantum dot device may include: a base; a fin extending away from the base, wherein the fin includes a quantum well layer; a gate above the fin; and a material on side faces of the fin; wherein the fin has a width between its side faces, and the fin is strained in the direction of the width.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Ta alloys that resist internal diffusion and provide superior mechanical strength to the wires.

A monofilament (100) for producing an Nb.sub.3Sn-containing superconductor wire (33) includes a powder core (1) with an Sn-containing powder, a reaction tube (3) composed of an Nb alloy that includes Nb and at least one further alloy component X. The powder core is disposed within the reaction tube. The monofilament also includes at least one source (4) for at least one partner component Pk. A respective source includes one or more source structures at a unitary radial position in the monofilament. The alloy component X and the partner component Pk form precipitates XPk on reaction annealing of the monofilament in which Sn from the powder core and Nb from the reaction tube react to produce Nb.sub.3Sn. The powder core is disposed in a moderation tube, which in turn is disposed within the reaction tube. This provides a monofilament for a powder-in-tube based Nb.sub.3Sn-containing superconductor wire with improved current carrying capacity.

A method for the production of a superconducting wire (20) uses a monofilament (1) having a powder core (3) that contains at least Sn and Cu, an inner tube (2), made of Nb or an alloy containing Nb, that encloses the powder core (3), and an outer tube (4) in which the inner tube (2) is arranged. The outer side of the inner tube (2) is in contact with the inner side of the outer tube (4) and the outer tube (4) is produced from Nb or from an alloy containing Nb. The outer tube is disposed in a cladding tube. The superconducting current carrying capacity of the superconducting wire is thereby improved.

A vertical q-capacitor includes a trench in a substrate through a layer of superconducting material. A superconductor is deposited in the trench forming a first film on a first surface, a second film on a second surface, and a third film of the superconductor on a third surface of the trench. The first and second surfaces are substantially parallel, and the third surface in the trench separates the first and second surfaces. A dielectric is exposed below the third film by etching. A first coupling is formed between the first film and a first contact, and a second coupling is formed between the second film and a second contact in a superconducting quantum logic circuit. The first and second couplings cause the first and second films to operate as the vertical q-capacitor that maintains integrity of data in the superconducting quantum logic circuit within a threshold level.

In various embodiments, superconducting wires incorporate diffusion barriers composed of Nb alloys or NbTa alloys that resist internal diffusion and provide superior mechanical strength to the wires.

In the production of an internal-tin-processed Nb.sub.3Sn superconducting wire, the present invention provides a Nb.sub.3Sn superconducting wire that is abundant in functionality, such as, the promotion of formation of a Nb.sub.3Sn layer, the mechanical strength of the superconducting filament (and an increase in interface resistance), the higher critical temperature (magnetic field), and the grain size reduction, and a method for producing it. A method for producing a Nb.sub.3Sn superconducting wire according to an embodiment of the present invention includes a step of providing a bar 10 that has a Sn insertion hole 12 provided in a central portion of the bar 10 and a plurality of Nb insertion holes 14 provided discretely along an outer peripheral surface of the Sn insertion hole 12, and that has an alloy composition being Cu-xZn-yM (x: 0.1 to 40 mass %, M=Ge, Ga, Mg, or Al, provided that, for Mg, x: 0 to 40 mass %), a step of mounting an alloy bar with an alloy composition of Sn-zQ (Q=Ti, Zr, or Hf) into the Sn insertion hole 12 and inserting Nb cores into the Nb insertion holes 14, a step of subjecting the bar 10 to diameter reduction processing to fabricate a Cu-xZn-yM/Nb/Sn-zQ composite multicore wire with a prescribed outer diameter, and a step of subjecting the composite multicore wire to Nb.sub.3Sn phase generation heat treatment.

A monofilament (100) for producing an Nb.sub.3 Sn-containing superconductor wire (33) includes a powder core (1) with an Sn-containing powder, a reaction tube (3) composed of an Nb alloy that includes Nb and at least one further alloy component X. The powder core is disposed within the reaction tube. The monofilament also includes at least two sources (4) for at least one partner component Pk. A respective source includes one or more source structures at a unitary radial position in the monofilament. The source structures are at different radial positions. The alloy component X and the partner component Pk form precipitates XPk on reaction annealing of the monofilament in which Sn from the powder core and Nb from the reaction tube react to produce Nb.sub.3 Sn. The powder core is disposed in a moderation tube, which is disposed within the reaction tube. This provides a monofilament with improved current carrying capacity.