Harvesting, coupling and control of single exciton coherences in photonic waveguide antennas

TL;DR

This paper demonstrates enhanced four-wave mixing detection of single quantum dot excitons using a dielectric waveguide antenna, revealing their coherence properties and inter-dot coupling, enabling advanced quantum control schemes.

Contribution

It introduces a waveguide antenna technique that significantly boosts FWM sensitivity and enables coherent control of single quantum dot excitons and their interactions.

Findings

FWM detection sensitivity increased by up to four orders of magnitude.

Revealed off-resonant F"orster coupling between quantum dots.

Achieved coherent control using higher order non-linearities.

Abstract

We perform coherent non-linear spectroscopy of individual excitons strongly confined in single InAs quantum dots (QDs). The retrieval of their intrinsically weak four-wave mixing (FWM) response is enabled by a one-dimensional dielectric waveguide antenna. Compared to a similar QD embedded in bulk media, the FWM detection sensitivity is enhanced by up to four orders of magnitude, over a broad operation bandwidth. Three-beam FWM is employed to investigate coherence and population dynamics within individual QD transitions. We retrieve their homogenous dephasing in a presence of spectral wandering. Two-dimensional FWM reveals off-resonant F\"orster coupling between a pair of distinct QDs embedded in the antenna. We also detect a higher order QD non-linearity (six-wave mixing) and use it to coherently control the FWM transient. Waveguide antennas enable to conceive multi-color coherent manipulation schemes of individual emitters.