Coherent Ultrafast Excitonic Oscillations in Monolayer WS$_2$

TL;DR

This study uses ab initio simulations to analyze and interpret coherent excitonic oscillations in monolayer WS$_2$, proposing a method to control these oscillations for ultrafast optoelectronic applications.

Contribution

First-principles time-dependent GW-BSE analysis of excitonic coherence in monolayer WS$_2$, with a proposed pump-probe scheme for controlled oscillation generation.

Findings

Identified microscopic origin of excitonic oscillations in WS$_2$

Provided a theoretical interpretation of recent experimental phenomena

Proposed a scheme for controlled generation of excitonic coherence

Abstract

Monolayer transition metal dichalcogenides are a suitable platform for studying excitonic coherence in the light-matter coupling regime. We present an ab initio time-dependent GW-Bethe-Salpeter equation (GW-BSE) investigation of coherent excitonic dynamics in monolayer WS$_2$. By solving the coherent coupling between the A, A$^{*}$, and B excitons under linearly polarized pump fields, we identify the microscopic origin of the resulting oscillatory dynamics and rationalize it using an effective theoretical model. Our results provide the interpretation of recently reported coherent excitonic phenomena in monolayer WS$_2$ (Nano Lett. 24, 8117 (2024)). Building on this first-principles time-resolved framework, we propose a tailored pump-probe scheme that enables the controlled generation and regeneration of coherent oscillations between excitonic states. These findings establish a predictive route for controlling excitonic coherence in two-dimensional materials, with direct relevance for ultrafast optoelectronic switches and solid-state quantum logic devices.