Observation of dressed excitonic states in a single quantum dot

TL;DR

This paper reports the experimental observation of dressed excitonic states in a single quantum dot, demonstrating control over excitonic energy levels and polarization properties using a strong laser field.

Contribution

It presents the first measurement of dressed states in a quantum dot, showing how the AC-Stark effect can erase exchange-induced splitting and manipulate polarization axes.

Findings

Exchange splitting can be erased by the AC-Stark effect.

Polarization axis of the quantum dot can be controlled.

Spectral signatures of dressed states are observed.

Abstract

We report the observation of dressed states of a quantum dot. The optically excited exciton and biexciton states of the quantum dot are coupled by a strong laser field and the resulting spectral signatures are measured using differential transmission of a probe field. We demonstrate that the anisotropic electron-hole exchange interaction induced splitting between the x- and y-polarized excitonic states can be completely erased by using the AC-Stark effect induced by the coupling field, without causing any appreciable broadening of the spectral lines. We also show that by varying the polarization and strength of a resonant coupling field, we can effectively change the polarization-axis of the quantum dot.