Bottom-up superconducting and Josephson junction devices inside a group-IV semiconductor

Abstract

Superconducting circuits are exceptionally flexible, enabling many different devices from sensors to quantum computers. Separately, epitaxial semiconductor devices such as spin qubits in silicon offer more limited device variation but extraordinary quantum properties for a solid-state system. It might be possible to merge the two approaches, making single-crystal superconducting devices out of a semiconductor by utilizing the latest atomistic fabrication techniques. Here we propose superconducting devices made from precision hole-doped regions within a silicon (or germanium) single crystal. We analyze the properties of this superconducting semiconductor and show that practical superconducting wires, Josephson tunnel junctions or weak links, superconducting quantum interference devices (SQUIDs), and qubits are feasible. This work motivates the pursuit of "bottom-up" superconductivity for improved or fundamentally different technology and physics.

9 pages, 4 figures; (v2) Fixed math error in estimate of the hole density and critical temperature for one doped atomic layer (all other numbers and figures are unchanged); even a single doped layer may be sufficient to observe superconductivity; (v3) accepted version