Valley entanglement of excitons in monolayers of transition-metal dichalcogenides

TL;DR

This paper demonstrates that linearly polarized photons can induce valley entanglement between excitons and free carriers in monolayer transition-metal dichalcogenides, enabling new quantum control without inter-valley interactions.

Contribution

It introduces a novel mechanism for valley entanglement in monolayer TMDs via photon absorption, independent of inter-valley coupling.

Findings

Valley entanglement can be generated by linearly polarized light.

Entanglement verified through photoluminescence polarization.

Photocurrent fluctuations also indicate valley entanglement.

Abstract

We show that excitons and free carriers in K and K' valleys of transition metal dichalcogenide monolayers can be entangled with respect to their valley degree of freedom by absorbing linearly polarized single photons. This effect does not require any interaction between K and K' excitons in contrast to conventional mechanisms of entanglement that are mediated by coupling between quantum systems (e.g.~entanglement of photons in nonlinear optical interactions). The valley entanglement of excitons and free carriers can be verified by measuring the polarization of their photoluminescence or fluctuations of the photocurrent under an applied in-plane DC bias.