Electrically driven photon emission from individual atomic defects in monolayer WS2

TL;DR

This paper demonstrates electrically stimulated photon emission from individual atomic defects in monolayer WS2, enabling atomic-scale, tunable single-photon sources with potential applications in quantum technologies.

Contribution

It introduces a method for electrically inducing photon emission from single defects in 2D materials with atomic precision and spectral tunability.

Findings

Atomic defects in WS2 can emit photons when electrically stimulated.

Emission maps match defect orbital electron densities.

Spectral characteristics are tunable via tip-sample voltage.

Abstract

Optical quantum emitters are a key component of quantum devices for metrology and information processing. In particular, atomic defects in 2D materials can operate as optical quantum emitters that overcome current limitations of conventional bulk emitters, such as yielding a high single-photon generation rate and offering surface accessibility for excitation and photon extraction. Here we demonstrate electrically stimulated photon emission from individual point defects in a 2D material. Specifically, by bringing a metallic tip into close proximity to a discrete defect state in the band gap of WS2, we induce inelastic tip-to-defect electron tunneling with an excess of transition energy carried by the emitted photons. We gain atomic spatial control over the emission through the position of the tip, while the spectral characteristics are highly customizable by varying the applied tip-sample voltage. Atomically resolved emission maps of individual sulfur vacancies and chromium substituent defects are in excellent agreement with the electron density of their respective defect orbitals as imaged via conventional elastic scanning tunneling microscopy. Inelastic charge-carrier injection into localized defect states of 2D materials thus provides a powerful platform for electrically driven, broadly tunable, atomic-scale single-photon sources.