Coherent coupling of dark and bright excitons with vibrational strain

TL;DR

This paper demonstrates that applying strain to a GaAs resonator enables coherent coupling of dark and bright excitons, making dark states optically accessible and suitable for quantum information applications.

Contribution

It introduces a novel method of using strain to coherently couple dark and bright excitons without external fields, advancing on-chip quantum technologies.

Findings

Strain breaks crystal symmetry, enabling dark-bright exciton coupling.

Dark states become optically accessible through strain-induced hybridization.

Coherent spin operations are achieved in the gigahertz regime.

Abstract

In many physical systems, there are specific electronic states called dark state that are protected from the rapid radiative decay imposed by the system symmetry. Although their long-lived nature indicates their potential for quantum information and spintronic applications, their high stability comes at the expense of optical accessibility. Breaking the symmetry by using magnetic and electric fields has been employed to hybridize dark and bright states thus making them optically active, but high-frequency and on-chip operation remains to be developed. Here we demonstrate the strain-induced coherent coupling of dark and bright exciton states in a GaAs mechanical resonator. The in-plane uniaxial strain breaks the rotational symmetry of the crystal, allowing the dark states to be optically accessible without any external fields. Such dark-bright coupling is tailored by the local strain distribution, which enables the coherent spin operation in the gigahertz regime and opens the way to on-chip excitonic quantum memories and circuits.