Coherent control of a V-type three-level system in a single quantum dot

TL;DR

This study demonstrates coherent control of a V-type three-level system in a quantum dot using polarized light, enabling manipulation of exciton states and spin via tailored laser pulses.

Contribution

It introduces a method to control exciton states in quantum dots through polarization-dependent excitation and explicitly solves the density matrix equations for comparison.

Findings

Polarization of the excitation field controls state coupling.

Population swapping between |x> and |y> states achieved.

Experimental results match density matrix simulations.

Abstract

In a semiconductor quantum dot, the Px and Py transitions to the polarization eigenstates, |x> and |y>, naturally form a three-level V-type system. Using low-temperature polarized photoluminescence spectroscopy, we have investigated the exciton dynamics arising under strong laser excitation. We also explicitly solved the density matrix equations for comparison with the experimental data. The polarization of the exciting field controls the coupling between the otherwise orthogonal states. In particular, when the system is initialized into |y>, a polarization-tailored pulse can swap the population into |x>, and vice-versa, effectively operating on the exciton spin.