Quantum dot spectroscopy using cavity QED

TL;DR

This paper demonstrates how tunable cavity QED with photonic crystal nanocavities enables detailed spectroscopy of quantum dots, revealing exciton states, fine structures, and novel exciton mixing effects.

Contribution

It introduces a deterministic coupling scheme in cavity QED that achieves unprecedented coupling strengths, allowing detailed quantum dot spectroscopy and discovery of new exciton interactions.

Findings

Identification of neutral and charged exciton transitions

Observation of a cavity-mediated mixing of bright and dark excitons

Achievement of coupling strengths over 0.15 meV

Abstract

Cavity quantum electrodynamics has attracted substantial interest, both due to its potential role in the field of quantum information processing and as a testbed for basic experiments in quantum mechanics. Here, we show how cavity quantum electrodynamics using a tunable photonic crystal nanocavity in the strong coupling regime can be used for single quantum dot spectroscopy. From the distinctive avoided crossings observed in the strongly coupled system we can identify the neutral and single positively charged exciton as well as the biexciton transitions. Moreover we are able to investigate the fine structure of those transitions and to identify a novel cavity mediated mixing of bright and dark exciton states, where the hyperfine interactions with lattice nuclei presumably play a key role. These results are enabled by a deterministic coupling scheme which allowed us to achieve unprecedented coupling strengths in excess of 0.15 meV.