Epitaxial Superconductor-Semiconductor Two-Dimensional Systems for Superconducting Quantum Circuits

TL;DR

This paper demonstrates how improved interface engineering between InAs and Al enables the fabrication of voltage-controlled Josephson junctions, advancing the development of tunable qubits and superconducting quantum circuits.

Contribution

It introduces a reliable method for fabricating voltage-controlled JJ-FETs with enhanced interface quality, enabling their use as tunable qubits, resonators, and switches in quantum circuits.

Findings

Successful fabrication of JJ-FETs with improved InAs-Al interface

Demonstration of tunability and control of qubit properties

Measurement of anharmonicity and coupling strengths in quantum systems

Abstract

Qubits on solid state devices could potentially provide the rapid control necessary for developing scalable quantum information processors. Materials innovation and design breakthroughs have increased functionality and coherence of qubits substantially over the past two decades. Here we show by improving interface between InAs as a semiconductor and Al as a superconductor, one can reliably fabricate voltage-controlled Josephson junction field effect transistor (JJ-FET) that can be used as tunable qubits, resonators, and coupler switches. We find that band gap engineering is crucial in realizing a two-dimensional electron gas near the surface. In addition, we show how the coupling between the semiconductor layer and the superconducting contacts can affect qubit properties. We present the anharmonicity and coupling strengths from one and two-photon absorption in a quantum two level system fabricated with a JJ-FET.