Dynamical Superfluid and Bose-Insulator Phases in Quantized Polariton Lattices

TL;DR

This paper explores how quantized energy levels in polariton lattices enable control over superfluid and Bose-insulating phases through nonlinear interactions, revealing dynamical phase transitions.

Contribution

It introduces a novel approach using Hilbert-space quantization in polariton lattices to manipulate quantum phases via nonlinear interactions and dynamical effects.

Findings

Weak nonlinearity supports a superfluid phase with broken U(1) symmetry.

Strong nonlinearity causes phase diffusion and suppresses coherence.

Transitions between phases can be sharp or gradual, driven by nonlinear effects.

Abstract

We demonstrate that Hilbert-space quantization in polariton lattices-manifested as multiple quantized energy levels in strongly confined sites-provides an unconventional route to realizing and manipulating different quantum phases. We show that nonlinear interactions transfer population into excited on-site quantum levels, which acts as an intrinsic dynamical channel controlling quantum coherence across the lattice. While weak nonlinearity confines polaritons to the lowest mode, yielding a robust superfluid phase with broken U(1) symmetry, strong nonlinearity induces phase diffusion through inter-level mixing. This dynamically generated fluctuations suppress global phase coherence and drives the system into a dynamical Bose-insulating phase. The changes between these phases occurs either as a nonequilibrium phase transition or a sharp crossover.