Abstract: In some implementations of the invention, a silicon dioxide (SiO2) insulating layer added between islands of a top YBCO layer of a Josephson Junction isolates a contact layer from YBCO (or other conductive components) in the Josephson Junction. In some implementations of the invention, a SiO2 insulating layer added between islands of a bottom YBCO layer of adjacent Josephson Junctions isolates the contact layer or other components from YBCO (or other conductive components) in the Josephson Junction. In some implementations of the invention, an etch stop layer may be deposited over the islands of the top YBCO layer prior to adding the SiO2 insulating layer. This etch stop layer protects the top YBCO layer during the adding of the SiO2 insulating layer and during subsequent formation of a via through the SiO2 to the etch stop layer.

Abstract: According to various implementations of the invention, high quality a-axis XBCO may be grown with low surface roughness. According to various implementations of the invention, low surface roughness may be obtained by: 1) adequate substrate preparation; 2) calibration of flux rates for constituent atoms; and/or 3) appropriate control of temperature during crystal growth. According to various implementations of the invention, a wafer comprises a smoothing layer of c-axis XBCO; a first conducting layer of a-axis XBCO formed on the smoothing layer; an insulating layer formed on the first conducting layer; and a second conducting layer of a-axis XBCO formed on the insulating layer, where, for a same surface roughness, a thickness of the smoothing layer and the first conducting layer combined is greater than a thickness of the first conducting layer without the smoothing layer.

Abstract: In some implementations of the invention, a silicon dioxide (SiO2) insulating layer added between islands of a top YBCO layer of a Josephson Junction isolates a contact layer from YBCO (or other conductive components) in the Josephson Junction. In some implementations of the invention, a SiO2 insulating layer added between islands of a bottom YBCO layer of adjacent Josephson Junctions isolates the contact layer or other components from YBCO (or other conductive components) in the Josephson Junction. In some implementations of the invention, an etch stop layer may be deposited over the islands of the top YBCO layer prior to adding the SiO2 insulating layer. This etch stop layer protects the top YBCO layer during the adding of the SiO2 insulating layer and during subsequent formation of a via through the SiO2 to the etch stop layer.