Superradiant and Dark Exciton States in an Optical Lattice within a Cavity

TL;DR

This paper investigates how ultracold atoms in an optical lattice coupled to a cavity form exciton states, including superradiant bright states and dark states, revealing their optical properties and strong coupling behavior.

Contribution

It introduces a detailed analysis of exciton modes in a cavity-coupled optical lattice, highlighting the formation of superradiant and dark states and their role in polariton formation.

Findings

Bright exciton states strongly couple to cavity photons

Dark states decouple from the cavity mode

Rabi splitting observed in strong coupling regime

Abstract

We study ultracold atoms in a finite size one-dimensional optical lattice prepared in the Mott insulator phase and commonly coupled to a single cavity mode. Due to resonance dipole-dipole interactions among the atoms, electronic excitations delocalize and form {\it excitons}. These exciton modes are divided into two groups: antisymmetric modes which decouple from the cavity mode forming {\it dark states}, and symmetric modes significantly coupled to the cavity mode called {\it bright states}. In typical setups the lowest and most symmetric exciton is coupled to the cavity photons much stronger than the other bright states and dominates the optical properties response of the atoms ({\it superradiant state}). In the strong coupling regime this superradiant state is coherently mixed with the cavity photon to form a doublet of polariton states with the Rabi splitting.