The optical Stark shift to control the dark exciton occupation of a quantum dot in a tilted magnetic field

TL;DR

This paper demonstrates how the optical Stark effect, combined with magnetic fields and laser pulses, can be used to prepare and control dark exciton states in quantum dots, with potential applications in photon generation.

Contribution

It introduces a novel method to manipulate dark excitons in quantum dots using optical Stark shifts and magnetic fields, providing analytic formulas and robustness analysis.

Findings

Effective dark exciton preparation using Stark shifts and laser pulses

Analytic formulas for optimal control parameters

Robustness against acoustic phonons

Abstract

When a detuned and strong laser pulse acts on an optical transition, a Stark shift of the corresponding energies occurs. We analyze how this optical Stark effect can be used to prepare and control the dark exciton occupation in a semiconductor quantum dot. The coupling between the bright and dark exciton states is facilitated by an external magnetic field. Using sequences of laser pulses, we show how the dark exciton and different superposition states can be prepared. We give simple analytic formulas, which yield a good estimate for optimal preparation parameters. The preparation scheme is quite robust against the influence of acoustic phonons. We further discuss the experimental feasibility of the used Stark pulses. Giving a clear physical picture our results will stimulate the usage of dark excitons in schemes to generate photons from quantum dots.