Excitations of strongly correlated polaritons

TL;DR

This paper analytically investigates the elementary excitations in the Jaynes-Cummings-Hubbard Model, revealing a Goldstone mode and an amplitude mode, with unique behaviors near the Mott transition and in polariton BEC regimes.

Contribution

It introduces an analytic slave-boson method to analyze excitations in strongly correlated polaritons within the JCHM, highlighting novel excitation features near phase transitions.

Findings

Identification of a gapless Goldstone mode and a gapped amplitude mode.

Observation of a peculiar anomaly in the Goldstone mode's sound velocity.

Persistence of features into the polariton BEC regime.

Abstract

We use an analytic slave-boson approach to calculate the elementary excitations of the Jaynes-Cummings-Hubbard Model (JCHM) describing strongly correlated polaritons on a lattice in various quantum optical systems. In the superfluid phase near the Mott transition we find a gapless, linear Goldstone mode and a gapped Amplitude mode corresponding to phase and density fluctuations, respectively. The sound velocity of the Goldstone mode develops a peculiar anomaly as a function of detuning at low densities, which persists into the weakly interacting regime of a polariton BEC.