Formation of Matter-Wave Polaritons in an Optical Lattice

TL;DR

This paper demonstrates the creation of matter-wave polaritons in an ultracold-atom optical lattice, enabling tunable, dissipation-free studies of polaritonic quantum phases and many-body transport phenomena.

Contribution

It introduces an ultracold-atom analogue of exciton-polaritons, replacing photons with atomic matter waves and excitons with atomic excitations, allowing full tunability and dissipation-free exploration.

Findings

Spectroscopic access to polariton band structure.

Observation of polaritonic superfluid and Mott-insulating phases.

Quantitative agreement with theoretical models.

Abstract

The polariton, a quasiparticle formed by strong coupling of a photon to a matter excitation, is a fundamental ingredient of emergent photonic quantum systems ranging from semiconductor nanophotonics to circuit quantum electrodynamics. Exploiting the interaction between polaritons has led to the realization of superfluids of light as well as of strongly correlated phases in the microwave domain, with similar efforts underway for microcavity exciton-polaritons. Here, we develop an ultracold-atom analogue of an exciton-polariton system in which interacting polaritonic phases can be studied with full tunability and without dissipation. In our optical-lattice system, the exciton is replaced by an atomic excitation, while an atomic matter wave is substituted for the photon under a strong dynamical coupling. We access the band structure of the matter-wave polariton spectroscopically by coupling the upper and lower polariton branches, and explore polaritonic many-body transport in the superfluid and Mott-insulating regimes, finding quantitative agreement with our theoretical expectations. Our work opens up novel possibilities for studies of polaritonic quantum matter.