Voltage-Controlled Superconducting Quantum Bus

TL;DR

This paper demonstrates a voltage-controlled superconducting quantum bus using an epitaxial semiconductor-superconductor nanowire, enabling tunable qubit coupling with high-speed switching and minimal coherence loss.

Contribution

It introduces a novel voltage-controlled superconducting switch that effectively tunes qubit interactions in a quantum bus without harming coherence.

Findings

Achieved up to 8-fold change in qubit-qubit coupling.

High-bandwidth switching on nanosecond timescales is possible.

Switching does not significantly degrade qubit coherence.

Abstract

We demonstrate the ability of an epitaxial semiconductor-superconductor nanowire to serve as a field-effect switch to tune a superconducting cavity. Two superconducting gatemon qubits are coupled to the cavity, which acts as a quantum bus. Using a gate voltage to control the superconducting switch yields up to a factor of 8 change in qubit-qubit coupling between the on and off states without detrimental effect on qubit coherence. High-bandwidth operation of the coupling switch on nanosecond timescales degrades qubit coherence.