Superconducting integrated circuits require several wiring layers to distribute bias and signals across the circuit, which must cross each other both with and without contacts. All wiring lines and contacts must be fully superconducting, and in the prior art each wiring layer comprises a single metallic thin film. An alternative wiring layer is disclosed that comprises sequential layers of two or more different metals. Such a multi-metallic wiring layer may offer improved resistance to impurity diffusion, better surface passivation, and/or reduction of stress, beyond that which is attainable with a single-metallic wiring layer. The resulting process leads to improved margin and yield in an integrated circuit comprising a plurality of Josephson junctions. Several preferred embodiments are disclosed, for both planarized and non-planarized processes. These preferred and other methods may be applied to digital circuits based on Rapid Single Flux Quantum logic, and to quantum computing using Josephson junction qubits.

A method for increasing the integration level of superconducting electronic circuits, comprising fabricating a series of planarized electrically conductive layers patterned into wiring, separated by planarized insulating layers, with vias communicating between the conductive layers. Contrary to the standard sequence of patterning from the bottom up, the pattern of vias in at least one insulating layer is formed prior to the pattern of wiring in the underlying conductive layer. This enables a reduction in the number of planarization steps, leading to a fabrication process which is faster and more reliable. In a preferred embodiment, the superconductor is niobium and the insulator is silicon dioxide. This method can provide 10 or more wiring layers in a complex integrated circuit, and is compatible with non-planarized circuits placed above the planarized wiring layers.

Provided are a method for manufacturing MgB.sub.2 superconductor by pressure molding a mixture of Mg powder or MgH.sub.2 powder and B powder and heat-treating the mixture, the method including (I) a step of adding a polycyclic aromatic hydrocarbon to the B powder, while heating the mixture to a temperature higher to or equal to the melting point of the polycyclic aromatic hydrocarbon at the time of this addition, and thereby covering the surface of the B powder with the polycyclic aromatic hydrocarbon; and (II) a step of mixing the B powder having the surface covered with the polycyclic aromatic hydrocarbon, with the Mg powder or the MgH.sub.2 powder, or a step of combining the B powder having the surface covered with the polycyclic aromatic hydrocarbon, with an Mg rod; and an MgB.sub.2 superconducting wire which has high critical current density (Jc) characteristics and less fluctuation in the critical current density (Jc).

A semifinished wire (1) for a superconducting wire containing Nb3Sn has a Cu stabilization cladding tube (2), a ring-shaped closed diffusion barrier (3) in the inside of the Cu stabilization cladding tube (2) and a plurality of PIT elements (6) in the inside of the diffusion barrier (3), each having a cladding (8) containing Cu, a small tube (9), and a powder core (10) containing Sn. The small tube (9) consists of Nb or an alloy containing Nb and the diffusion barrier (3) has a percentage of area ADF in cross-section of the semifinished wire (1) of 3% ADF 9% and a wall thickness WDF with 8 μm≦WDF≦25 μm. A plurality of filler elements (5) are arranged inside the diffusion barrier (3), with the inner sides of the filler elements (5) abutting the PIT elements (6).

A current limiter arrangement limiting an electric current between a first and a second terminal includes a first current limiting device and a second current limiting device arranged between the first and the second terminal. The first and the second current limiting device each include a substrate having a substrate surface area and a substrate thickness, and include a superconducting section arranged on the substrate and thermally coupled to the substrate thereby covering a coupling surface area on the substrate. Each of the superconducting sections has a critical current value and the substrate surface areas, the substrate thicknesses and or the coupling surface areas are implemented as a function of the critical current values.

The method is for manufacturing a high temperature multi-filamentary superconducting tape wire having an oxide superconducting layer formed on a tape-shaped metal substrate with an intermediate layer therebetween and a metal stabilizing layer formed on the oxide superconducting layer, wherein one or more lengthwise slits are formed in the oxide superconducting layer and the intermediate layer and no slits are formed in the metal substrate and the stabilizing layer. The method includes: a step for preparing a high temperature superconducting wire material having an oxide superconducting layer formed on a tape-shape metal substrate with an intermediate layer therebetween and a stabilizing layer formed on the oxide superconducting layer; and a step for applying a load to the high temperature superconducting wire material to form slits. The method enables simple manufacturing of a high temperature superconducting wire material having a finer superconducting layer without sacrificing superconducting performance and mechanical strength.

A parametric traveling wave amplifier (200) is disclosed in which the amplifiers include: a co-planar waveguide, in which the co-planar waveguide includes at least one Josephson junction (210) interrupting a center trace (204) of the co-planar waveguide; and at least one shunt capacitor coupled to the co-planar waveguide, in which each shunt capacitor of the at least one shunt capacitor includes a corresponding superconductor trace (214) extending over an upper surface of the center trace of the co-planar waveguide, and in which a gap separates the superconductor trace from the upper surface of the center trace, and in which the co-planar waveguide including the at least one Josephson junction and the shunt capacitor establish a predefined overall impedance for the traveling wave parametric amplifier.

A method of forming a kilometer(s)-length high temperature superconductor tape by feeding a textured tape from roll-to-roll through a reactor chamber, flowing high temperature superconductor precursors from an elongated precursor showerhead positioned in the chamber the elongation in a direction along the tape; flowing gas from first and second elongated gas curtain shower heads on either side of the precursor showerhead; and illuminating the upper surface of the tape with illumination from sources on opposing sides of the reactor, the illumination sources positioned so as to allow illumination to pass under a respective one of the curtain shower heads and under the precursor showerhead to the upper surface of the tape.

An electronic device includes a pair of depletion gates, an accumulation gate, and a conductive resonator. The depletion gates are spaced apart from each other. The accumulation gate is over the depletion gates. The conductive resonator is over the depletion gates and the accumulation gate. The conductive resonator includes a first portion, a second portion, and a third portion. The first portion and the second portion are on opposite sides of the accumulation gate. The third portion interconnects the first and second portions of the conductive resonator and across the depletion gates. A bottom surface of the first portion of the conductive resonator is lower than a bottom surface of the accumulation gate.

Techniques regarding lithographic processes for fabricating Josephson junctions are provided. For example, one or more embodiments described herein can comprise a method that can include depositing a first resist layer onto a second resist layer. The first resist layer can include a bridge portion that defines an opening for forming a Josephson junction. The method can also comprise depositing a third resist layer onto the bridge portion. The third resist layer can shield the opening from an angled deposition of a superconducting material during fabrication of the Josephson junction.