A Semiconductor Nanowire-Based Superconducting Qubit

TL;DR

This paper presents a hybrid semiconductor nanowire-based superconducting qubit, demonstrating coherent control, long relaxation and dephasing times, and advantages of voltage-based control over flux-based methods, suitable for topological quantum computing.

Contribution

Introduction of a novel gatemon qubit using semiconductor nanowires with superconducting layers, enabling gate-controlled Josephson energy and operation in magnetic fields.

Findings

Achieved relaxation time of 0.8 microseconds.

Achieved dephasing time of 1 microsecond.

Demonstrated coherent control via gate voltage pulses.

Abstract

We introduce a hybrid qubit based on a semiconductor nanowire with an epitaxially grown superconductor layer. Josephson energy of the transmon-like device ("gatemon") is controlled by an electrostatic gate that depletes carriers in a semiconducting weak link region. Strong coupling to an on-chip microwave cavity and coherent qubit control via gate voltage pulses is demonstrated, yielding reasonably long relaxation times (0.8 {\mu}s) and dephasing times (1 {\mu}s), exceeding gate operation times by two orders of magnitude, in these first-generation devices. Because qubit control relies on voltages rather than fluxes, dissipation in resistive control lines is reduced, screening reduces crosstalk, and the absence of flux control allows operation in a magnetic field, relevant for topological quantum information.