Brobdingnagian photon bunching in cathodoluminescence of excitons in WS$_2$ monolayer

TL;DR

This study demonstrates extreme photon bunching in WS2 monolayers using cathodoluminescence, with the potential to synchronize quantum emitters for quantum information applications.

Contribution

It introduces a method to achieve record-high photon bunching in WS2 monolayers by optimizing electron-beam excitation and nanostructure geometry.

Findings

Photon bunching up to g2(0)=156 in WS2 monolayers.

Record-high bunching g2(0)=2152 achieved with gold nanodisks.

Photon bunching depends strongly on electron-beam current density.

Abstract

Cathodoluminescence spectroscopy in conjunction with second-order auto-correlation measurements of $g_2(\tau)$ allows to extensively study the synchronization of quantum light sources in low-dimensional structures. Co-existing excitons in two-dimensional transition metal dichalcogenide monolayers provide a great source of identical quantum emitters which can be simultaneously excited by an electron. In this article, we demonstrate large photon bunching with $g_2(0)$ up to $156\pm16$ of a tungsten disulfide monolayer, exhibiting a strong dependence on the electron-beam current density. To further improve the excitation synchronization and the electron-emitter interaction, we show exemplary that the careful selection of a simple and compact geometry -- a thin, monocrystalline gold nanodisk -- can be used to realize a record-high bunching $g_2(0)$ of up to $2152\pm236$. This approach to control the electron excitation of excitons in a \ce{WS2} monolayer allows for the synchronization of quantum emitters in an ensemble, which is important to further advance quantum information processing and computing technologies.