One or more systems, devices, methods of use and/or methods of fabrication herein relate to superconducting monolithic microwave integrated circuits. According to an embodiment, a device comprises a monolithic microwave integrated circuit comprising a superconducting layer coupled to a first circuit element and to a second circuit element, wherein a material of the superconducting layer comprises Tantalum Nitride.

A semiconductor structure and methods of forming the semiconductor structure generally includes providing a thermocompression bonded superconducting metal layer sandwiched between a first silicon substrate and a second silicon substrate. The second substrate includes a plurality of through silicon vias to the thermocompression bonded superconducting metal layer. A second superconducting metal is electroplated into the through silicon vias using the thermocompression bonded superconducting metal layer as a bottom electrode during the electroplating process, wherein the filling is from the bottom upwards.

A method of constructing a superconducting switch includes depositing a thin sacrificial layer on top of a substrate. The sacrificial layer is patterned to remove portions of the sacrificial layer except at a first portion of the substrate. A superconducting metal layer is patterned on top of the substrate and on top of the sacrificial layer. The superconducting metal layer is patterned to form a superconducting metal line over the sacrificial layer. The patterned sacrificial layer is etched from under the superconducting metal line to release the metal line from the substrate.

A method of fabrication of a superconducting device includes forming a first portion of the superconducting device on a first chip, a second portion of the superconducting device on a second chip, and bonding the first chip to the second chip, arranged in a flip-chip configuration. The first portion of the superconducting device on the first chip includes a dissipative portion of the superconducting device. A multi-layer superconducting integrated circuit is implemented so that noise-susceptible superconducting devices are positioned in wiring layers formed from a low-noise superconductive material and that underlie wiring layers that are formed from a different superconductive material. A superconducting integrated circuit has a first stack with a first superconducting wiring layer formed from a first high kinetic inductance material and a second superconducting wiring layer communicatively coupled to the first superconducting wiring layer to form a first control circuit, a second stack comprising a third superconducting wiring layer formed from a second high kinetic inductance material and a fourth superconducting wiring layer communicatively coupled the third superconducting wiring layer to form a second control circuit. The superconducting integrated circuit also has a third stack with a controllable device, and at least one of the first control circuit and the second control circuit is communicatively coupled to the controllable device.

A device includes: a first chip including a qubit; and a second chip bonded to the first chip, the second chip including a substrate including first and second opposing surfaces, the first surface facing the first chip, wherein the second chip includes a single layer of superconductor material on the first surface of the substrate, the single layer of superconductor material including a first circuit element. The second chip further includes a second layer on the second surface of the substrate, the second layer including a second circuit element. The second chip further includes a through connector that extends from the first surface of the substrate to the second surface of the substrate and electrically connects a portion of the single layer of superconducting material to the second circuit element.

Various techniques and apparatus permit fabrication of superconductive circuits. A superconducting integrated circuit comprising a superconducting stud via, a kinetic inductor, and a capacitor may be formed. Forming a superconducting stud via in a superconducting integrated circuit may include masking with a hard mask and masking with a soft mask. Forming a superconducting stud via in a superconducting integrated circuit may include depositing a dielectric etch stop layer. Interlayer misalignment in the fabrication of a superconducting integrated circuit may be measured by an electrical vernier. Interlayer misalignment in the fabrication of a superconducting integrated circuit may be measured by a chain of electrical verniers and a Wheatstone bridge. A superconducting integrated circuit with three or more metal layers may include an enclosed, matched, on-chip transmission line. A metal wiring layer in a superconducting integrated circuit may be encapsulated.

Electrical, mechanical, computing, and/or other devices that include components formed of extremely low resistance (ELR) materials, including, but not limited to, modified ELR materials, layered ELR materials, and new ELR materials, are described.

Fabricating wiring layers above a Josephson junction multi-layer may include removing a part of the multilayer; depositing an insulating layer to overlie a part of the multilayer; and patterning the insulating layer to define a hole in the insulating layer. The method includes depositing a first superconducting wiring layer over a part of the insulating layer and within a portion of the hole. Further, insulating and wiring layers may be deposited and a topmost wiring layer defined. The method includes depositing a passivating layer to overlie the topmost wiring layer. Fabricating a superconducting integrated circuit comprising a hybrid dielectric system may include depositing a high-quality dielectric layer that overlies a superconducting feature. The method includes depositing a second dielectric layer that overlies at least part of the high-quality dielectric layer. The second dielectric layer can comprise a conventional dielectric material.

A capacitive coupling device (superconducting C-coupler) includes a trench formed through a substrate, from a backside of the substrate, reaching a depth in the substrate, substantially orthogonal to a plane of fabrication on a frontside of the substrate, the depth being less than a thickness of the substrate. A superconducting material is deposited as a continuous conducting via layer in the trench with a space between surfaces of the via layer in the trench remaining accessible from the backside. A superconducting pad is formed on the frontside, the superconducting pad coupling with a quantum logic circuit element fabricated on the frontside. An extension of the via layer is formed on the backside. The extension couples to a quantum readout circuit element fabricated on the backside.

Described herein are structures that include interconnects for providing electrical connectivity in superconducting quantum circuits. One structure includes a first and a second interconnects provided over a surface of an interconnect support layer, e.g. a substrate, on which superconducting qubits are provided, a lower interconnect provided below such surface (i.e. below-plane interconnect), and vias for providing electrical interconnection between the lower interconnect and each of the first and second interconnects. Providing below-plane interconnects in superconducting quantum circuits allows realizing superconducting and mechanically stable interconnects. Implementing below-plane interconnects by bonding of two substrates, material for which could be selected, allows minimizing the amount of spurious two-level systems in the areas surrounding below-plane interconnects while allowing different choices of materials to be used. Methods for fabricating such structures are disclosed as well.