Spontaneous Emission Spectrum in Double Quantum Dot Devices

TLDR

A double quantum dot device functions as a tunable two‑level system where inelastic transitions exchange energy with bosonic modes, primarily acoustic phonons, and are described by Einstein coefficients linking absorption, stimulated, and spontaneous emission. The study measures elastic and inelastic transition rates by recording the dc electron current through the double quantum dot. Experiments show that vacuum fluctuations in the environment significantly influence coherent quantum 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.