Optical manipulation of layer-valley coherence via strong exciton-photon coupling in microcavities

TL;DR

This paper demonstrates the control of layer-valley coherence in bilayer WS2 by coupling valley excitons to microcavity photons, utilizing pseudomagnetic fields from TE-TM splitting, offering a new method for quantum control without large magnets or high-power lasers.

Contribution

It introduces a novel approach to manipulate valley coherence using strong exciton-photon coupling and cavity-induced pseudomagnetic fields in 2D materials.

Findings

Valley coherence can be controlled via cavity-induced pseudomagnetic fields.

Strong exciton-photon coupling enables manipulation of valley states.

Optical cavities can replace large magnets or high-power lasers for valley control.

Abstract

Coherent control and manipulation of quantum degrees of freedom such as spins forms the basis of emerging quantum technologies. In this context, the robust valley degree of freedom and the associated valley pseudospin found in two-dimensional transition metal dichalcogenides is a highly attractive platform. Valley polarization and coherent superposition of valley states have been observed in these systems even up to room temperature. Control of valley coherence is an important building block for the implementation of valley qubit. Large magnetic fields or high-power lasers have been used in the past to demonstrate the control (initialization and rotation) of the valley coherent states. Here we demonstrate control of layer-valley coherence via strong coupling of valley excitons in bilayer WS2 to microcavity photons by exploiting the pseudomagnetic field arising in optical cavities owing to the TE-TM splitting. The use of photonic structures to generate pseudomagnetic fields which can be used to manipulate exciton-polaritons presents an attractive approach to control optical responses without the need for large magnets or high intensity optical pump powers.