Microwave detection of electron-phonon interactions in a cavity-coupled double quantum dot

TL;DR

This study investigates electron-phonon interactions in a suspended InAs nanowire double quantum dot coupled to a microwave cavity, revealing how phonons influence cavity response and frequency through direct measurements and theoretical analysis.

Contribution

It provides the first direct measurement of electron-phonon coupling strength in a cavity-coupled double quantum dot system using microwave techniques.

Findings

Cavity phase shift varies periodically with DQD energy detuning.

Observed cavity frequency renormalization aligns with phonon coupling theory.

Electron-phonon interactions modulate cavity response in quantum dot systems.

Abstract

Quantum confinement leads to the formation of discrete electronic states in quantum dots. Here we probe electron-phonon interactions in a suspended InAs nanowire double quantum dot (DQD) that is electric-dipole coupled to a microwave cavity. We apply a finite bias across the wire to drive a steady state population in the DQD excited state, enabling a direct measurement of the electron-phonon coupling strength at the DQD transition energy. The amplitude and phase response of the cavity field exhibit features that are periodic in the DQD energy level detuning due to the phonon modes of the nanowire. The observed cavity phase shift is consistent with theory that predicts a renormalization of the cavity center frequency by coupling to phonons.