# Tomography of optical polarization rotation induced by a quantum dot-cavity device

## TL;DR

This paper presents a tomography method to analyze the polarization response of a quantum dot-cavity device, revealing how quantum dot resonance fluorescence influences polarization rotation and purity.

## Contribution

It introduces a novel tomography approach to characterize optical polarization rotation in quantum dot-cavity systems beyond semiclassical models.

## Key findings

- Quantum dot induces a 20° polarization rotation in the Poincaré sphere.
- Polarization purity remains above 84% despite rotation.
- Coherent fluorescence contributes to polarization rotation, incoherent fluorescence degrades purity.

## Abstract

We introduce a tomography approach to describe the optical response of a cavity quantum electrodynamics device, beyond the semiclassical image of polarization rotation, by analyzing the polarization density matrix of the reflected photons in the Poincar\'e sphere. Applying this approach to an electrically-controlled quantum dot-cavity device, we show that a single resonantly-excited quantum dot induces a large optical polarization rotation by $20^\circ$ in latitude and longitude in the Poincar\'e sphere, with a polarization purity remaining above $84\%$. The quantum dot resonance fluorescence is shown to contribute to the polarization rotation via its coherent part, whereas its incoherent part contributes to degrading the polarization purity.