# Engineering Effects of Vacuum Fluctuations on Two-dimensional Semiconductors

## TL;DR

This paper demonstrates how vacuum fluctuations can significantly alter exciton properties in two-dimensional semiconductors, enabling control over optical and valley polarization effects through vacuum engineering.

## Contribution

It provides the first experimental observation of large vacuum-induced renormalization effects in 2D materials and shows how to manipulate these effects via vacuum energy density tuning.

## Key findings

- Large renormalization of exciton resonance and decay rate observed
- Control of Lamb shift, radiative decay, and valley polarization achieved
- Vacuum engineering enables manipulation of exciton and charged exciton emissions

## Abstract

The resonance energy and the transition rate of atoms, molecules and solids were understood as their intrinsic properties in classical electromagnetism. With the development of quantum electrodynamics, it is realized that these quantities are linked to the coupling of the transition dipole and the quantum vacuum. Such effects can be greatly amplified in macroscopic many-body systems from virtual photon exchange between dipoles, but are often masked by inhomogeneity and pure dephasing, especially in solids. Here, we observe an exceptionally large renormalization of exciton resonance and radiative decay rate in transition metal dichalcogenides monolayers due to interactions with the vacuum in both absorption and emission spectroscopy. Tuning the vacuum energy density near the monolayer, we demonstrate control of cooperative Lamb shift, radiative decay, and valley polarization as well as control of the charged exciton emission. Our work establishes a simple and robust experimental system for vacuum engineering of cooperative matter-light interactions.

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Source: https://tomesphere.com/paper/1903.06645