Engineering radiative coupling of excitons in 2D semiconductors

Abstract

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