Spontaneous Emission Spectrum in Double Quantum Dot Devices

TL;DR

This paper investigates the spontaneous emission spectrum in double quantum dot devices, highlighting the role of acoustic phonons and vacuum fluctuations in quantum coherence and transition rates.

Contribution

It provides experimental analysis of inelastic transition rates in double quantum dots, emphasizing the influence of environmental bosons and vacuum fluctuations.

Findings

Inelastic transition rates align with Einstein coefficients.

Acoustic phonons significantly affect emission spectra.

Vacuum fluctuations impact quantum coherence in devices.

Abstract

A double quantum dot device is a tunable two-level system for electronic energy states. A dc electron current directly measures the rates for elastic and inelastic transitions between the two levels. For inelastic transitions energy is exchanged with bosonic degrees of freedom in the environment. The inelastic transition rates are well described by the Einstein coefficients, relating absorption with stimulated and spontaneous emission. The most effectively coupled bosons in the specific environment of our semiconductor device are acoustic phonons. The experiments demonstrate the importance of vacuum fluctuations in the environment for little circuits of coherent quantum devices.