Quantum information processing device formation

A method, comprising:

• forming at least part of a quantum information processing device, comprising:
• providing a first electrically-conductive layer formed of a first electrically-conductive material on a principal surface of a substrate;
• patterning the first electrically-conductive layer into a first electrically-conductive base, a second electrically-conductive base, and a center electrically-conductive strip arranged between the first electrically-conductive base and the second electrically-conductive base, wherein the center electrically-conductive strip is separated from the first electrically-conductive base and the second electrically-conductive base by a first window in the first electrically-conductive layer and a second window in the first electrically-conductive layer, respectively;
• depositing a layer of dielectric material on the first electrically-conductive material;
• patterning the layer of dielectric material to form a pad of dielectric material and to reveal a first region of the first electrically-conductive layer and a second region of the first electrically-conductive layer, wherein the first region is on the first electrically-conductive base and the second region is on the second electrically-conductive base;
• depositing a second electrically-conductive layer on the pad of dielectric material, on the first region, and on the second region of the first electrically-conductive layer;
• patterning the second electrically-conductive layer to obtain a bridge structure, wherein the bridge structure spans the center electrically-conductive strip;
• and
• removing the pad of dielectric material using isotropic gas phase etching.