International Business Machines Corporation

Benjamin B Wymore

Markus Brink

Christian Lavoie

Keith E Fogel

Jeng-Bang Yau

Martin O Sandberg

Vivekananda P Adiga

John Bruley

Ali Afzali-Ardakani

David Lee Rath

George Gabriel Totir

Stephen L Brown

Sweet Jean L

Techniques facilitating formation of amorphous superconducting alloys for superconducting circuits are provided. A device can comprise one or more superconducting components that comprise an amorphous superconducting alloy comprising two or more elements. At least one element of the two or more elements is a superconducting element.

Amorphous superconducting alloys for superconducting circuits

A method of increasing grain size of polycrystalline superconducting materials for superconducting circuits, includes forming an initial superconducting epitaxial layer lattice matched to a substrate formed of a substrate material, the initial superconducting epitaxial layer formed of a compound including the substrate material and a first metal; and forming a second layer of the first metal on the initial superconducting epitaxial layer and heating the layers to increase a thickness of the initial superconducting epitaxial layer formed of the compound.

Increasing grain size of polycrystalline superconducting materials for superconducting circuits

Systems and techniques that facilitate spurious junction prevention via in-situ ion milling are provided. In various embodiments, a method can comprise forming a tunnel barrier of a Josephson junction on a substrate during a shadow evaporation process. In various instances, the method can further comprise etching an exposed portion of the tunnel barrier during the shadow evaporation process. In various embodiments, the shadow evaporation process can comprise patterning a resist stack onto the substrate. In various instances, the etching the exposed portion of the tunnel barrier can leave a protected portion of the tunnel barrier within a shadow of the resist stack. In various instances, the shadow of the resist stack can be based on a direction of the etching the exposed portion of the tunnel barrier. In various embodiments, the shadow evaporation process can further comprise depositing a first superconducting material on the substrate after the patterning the resist stack, oxidizing a surface of the first superconducting material to form the tunnel barrier, and depositing a second superconducting material over the protected portion of the tunnel barrier to form a Josephson junction. In various instances, the etching the exposed portion of the tunnel barrier can occur after the oxidizing the surface of the first superconducting material and before the depositing the second superconducting material.

Spurious junction prevention via in-situ ion milling

A superconducting circuit includes a Josephson junction device including a lower superconducting material layer formed on a substrate and a junction layer formed on the lower superconducting material layer. The superconducting circuit also includes an upper superconducting material layer formed over the junction layer. At least the lower superconducting material layer comprises grains having a size that is larger than a size of the Josephson junction.

Grain size control of superconducting materials in thin films for Josephson junctions

A method of fabricating a superconductor device includes providing a first metal layer on top of the substrate. An oxidation of a top surface of the first metal layer is rejected. A second metal layer is deposited on top of the second metal layer. A superconducting alloy of the first metal layer and the second metal layer is created between the first metal layer and the second metal layer. There is no oxide layer between the superconducting alloy and the first metal layer.

Superconducting structure and device surface termination with alloy

A method of measuring contact resistance at an interface for superconducting circuits is provided. The method includes using a chain structure of superconductors to measure a contact resistance at a contact between contacting superconductor. The method further includes eliminating ohmic resistance from wire lengths in the chain structure by operating below the lowest superconducting transition temperature of all the superconductors in the chain structure. The measurement is dominated by contact resistances of the contacts between contacting superconductors in the chain.

Methods and structure to probe the metal-metal interface for superconducting circuits

A method of making a Josephson junction for a superconducting qubit includes providing a substructure having a surface with first and second trenches perpendicular to each other defined therein. The method further includes evaporating a first superconducting material to deposit the first superconducting material and evaporating a second superconducting material to deposit the second superconducting material in the first trench to provide a first lead, and forming an oxidized layer on the first and second superconducting materials. The method includes evaporating a third superconducting material at an angle substantially perpendicular to the surface of the substructure to deposit the third superconducting material in the second trench without rotating the substructure to form a second lead. A vertical Josephson junction is formed at the intersection of the first and second trenches electrically connected through the first lead and through the second lead.

Junction fabrication method for forming qubits

Enhanced compositions and methods are provided for selectively etching silicon wafers, which is particularly useful in the context of silicon wafer manufacturing and processing applications. Optionally, a formulation is provided which selectively etches silicon dioxide in preference to aluminum oxide. Optionally, a formulation and method are provided that is substantially non-aqueous.

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Cortlandt Manor, NY, United States of America

Benjamin B Wymore