Bright and dark excitons in an atom--pair filled optical lattice within a cavity

TL;DR

This paper investigates excitonic states in a degenerate atomic gas within an optical lattice coupled to a cavity, revealing how symmetric and antisymmetric states interact with photons and exhibit unique dispersion and spectral properties.

Contribution

It introduces a model for bright and dark excitons in atom pairs in optical lattices, analyzing their coupling to cavity photons and resulting polariton formation, highlighting new solid-state phenomena.

Findings

Symmetric states form long-range excitons coupled to cavity photons.

Antisymmetric states remain localized and dark.

Cavity spectra reveal exciton-polariton dispersion relations.

Abstract

We study electronic excitations of a degenerate gas of atoms trapped in pairs in an optical lattice. Local dipole-dipole interactions produce a long lived antisymmetric and a short lived symmetric superposition of individual atomic excitations as the lowest internal on-site excitations. Due to the much larger dipole moment the symmetric states couple efficiently to neighbouring lattice sites and can be well represented by Frenkel excitons, while the antisymmetric dark states stay localized. Within a cavity only symmetric states couple to cavity photons inducing long range interactions to form polaritons. We calculate their dispersion curves as well as cavity transmission and reflection spectra to observe them. For a lattice with aspherical sites bright and dark states get mixed and their relative excitation energies depend on photon polarizations. The system should allow to study new types of solid state phenomena in atom filled optical lattices.