Dressed excitonic states and quantum interference in a three-level quantum dot ladder system

TL;DR

This paper demonstrates dressed states and quantum interference in a driven three-level quantum dot system, revealing coherence effects under strong illumination relevant for quantum information and nonlinear optics.

Contribution

It reports the observation of quantum interference effects and dressed states in a solid-state quantum dot system under strong driving conditions, highlighting coherence preservation.

Findings

Autler-Townes splitting observed at high coupling energy

Quantum interference effects depend on pump/probe geometry

Coherence maintained under intense illumination

Abstract

We observe dressed states and quantum interference effects in a strongly driven three-level quantum dot ladder system. The effect of a strong coupling field on one dipole transition is measured by a weak probe field on the second dipole transition using differential reflection. When the coupling energy is much larger than both the homoge-neous and inhomogeneous linewidths an Autler-Townes splitting is observed. Striking differences are observed when the transitions resonant with the strong and weak fields are swapped, particularly when the coupling energy is nearly equal to the measured linewidth. This result is attributed to quantum interference: a modest destructive or constructive interference is observed depending on the pump / probe geometry. The data demonstrate that coher-ence of both the bi-exciton and the exciton is maintained in this solid-state system, even under intense illumina-tion, which is crucial for prospects in quantum information processing and non-linear optical devices.