Controlling the Dark Exciton Spin Eigenstates by External Magnetic Field

TL;DR

This paper demonstrates how an external magnetic field can coherently control the spin states of dark excitons, using polarization measurements and a master equation model, without reducing decoherence times.

Contribution

It introduces a method to manipulate dark exciton spin eigenstates with magnetic fields while preserving coherence, supported by experimental and theoretical analysis.

Findings

Successful control of dark exciton eigenstates with magnetic fields

Decoherence times remain unaffected during control

Experimental results align with computational models

Abstract

We study the dark exciton's behavior as a coherent physical two-level spin system (qubit) using an external magnetic field in the Faraday configuration. Our studies are based on polarization-sensitive intensity autocorrelation measurements of the optical transition resulting from the recombination of a spin-blockaded biexciton state, which heralds the dark exciton and its spin state. We demonstrate control over the dark exciton eigenstates without degrading its decoherence time. Our observations agree well with computational predictions based on a master equation model.