Keeping the photon in the dark: Enabling full quantum dot control by chirped pulses and magnetic fields

TL;DR

This paper demonstrates a novel all-optical method to control and retrieve dark excitons in quantum dots using chirped pulses and magnetic fields, enabling potential quantum information applications.

Contribution

It introduces a new technique for controlling dark excitons in quantum dots without relying on decay processes, combining chirped pulses and magnetic fields for quantum control.

Findings

Successful all-optical storage and retrieval of dark excitons.

Experimental results match theoretical predictions.

Enables new quantum control and photon entanglement methods.

Abstract

Because dark excitons in quantum dots are not directly optically accessible, so far they have not played a significant role in using quantum dots for photon generation. They possess significantly longer lifetimes than their brighter counterparts and hence offer enormous potential for photon storage or manipulation. In this work, we demonstrate an all-optical storage and retrieval of the spin-forbidden dark exciton in a quantum dot from the ground state employing chirped pulses and an in-plane magnetic field. Our experimental findings are in excellent agreement with theoretical predictions of the dynamics calculated using state-of-the-art product tensor methods. Our scheme enables an all-optical control of dark states without relying on any preceding decays. This opens up a new dimension for optimal quantum control and time-bin entangled photon pair generation from quantum dots.