Quantum Fluctuations, Temperature and Detuning Effects in Solid-Light Systems

TL;DR

This paper investigates the superfluid to Mott insulator transition in cavity polariton arrays, highlighting the effects of quantum fluctuations, temperature, and detuning on phase diagrams and excitation spectra, with implications for experimental realizations.

Contribution

It provides a detailed analysis of phase diagrams and excitation spectra in cavity polariton systems, incorporating quantum fluctuations exactly and exploring the impact of detuning and temperature.

Findings

Quantum fluctuations significantly affect phase boundaries.

Detuning alters the nature of bosonic particles in the system.

Mott state persists up to experimentally accessible temperatures.

Abstract

The superfluid to Mott insulator transition in cavity polariton arrays is analyzed using the variational cluster approach, taking into account quantum fluctuations exactly on finite length scales. Phase diagrams in one and two dimensions exhibit important non-mean-field features. Single-particle excitation spectra in the Mott phase are dominated by particle and hole bands separated by a Mott gap. In contrast to Bose-Hubbard models, detuning allows for changing the nature of the bosonic particles from quasi-localized excitons to polaritons to weakly interacting photons. The Mott state with density one exists up to temperatures $T/g\gtrsim0.03$, implying experimentally accessible temperatures for realistic cavity couplings $g$.