Controlling the polarization eigenstate of a quantum dot exciton with light

TL;DR

This paper demonstrates optical control of a quantum dot's polarization eigenstates by tuning nuclear spins with laser power, enabling the quantum dot to act as a tunable light polarization converter.

Contribution

It introduces a method to control quantum dot exciton polarization states using optical pumping without external magnetic fields.

Findings

Controlled the polarization eigenstates via optical pumping.

Achieved tunable nuclear magnetic fields affecting exciton emission.

Quantum dot acts as a tunable polarization converter.

Abstract

We demonstrate optical control of the polarization eigenstates of a neutral quantum dot exciton without any external fields. By varying the excitation power of a circularly polarized laser in micro-photoluminescence experiments on individual InGaAs quantum dots we control the magnitude and direction of an effective internal magnetic field created via optical pumping of nuclear spins. The adjustable nuclear magnetic field allows us to tune the linear and circular polarization degree of the neutral exciton emission. The quantum dot can thus act as a tunable light polarization converter.