Critical fluctuations in an optical parametric oscillator: when light behaves like magnetism

TL;DR

This paper investigates critical phenomena in a nondegenerate optical parametric oscillator near threshold, revealing its connection to XY-type models with a tricritical Lifshitz point and exploring quantum correlations.

Contribution

It introduces a universal equation for the system, linking optical criticality to statistical models, and provides detailed numerical and analytical analysis of quantum correlations.

Findings

Quadrature correlations exhibit XY-type critical behavior

Identification of a tricritical Lifshitz point in the system

Accurate non-Gaussian correlation calculations

Abstract

We study the nondegenerate optical parametric oscillator in a planar interferometer near threshold, where critical phenomena are expected. These phenomena are associated with nonequilibrium quantum dynamics that are known to lead to quadrature entanglement and squeezing in the oscillator field modes. We obtain a universal form for the equation describing this system, which allows a comparison with other phase transitions. We find that the unsqueezed quadratures of this system correspond to a two-dimensional XY-type model with a tricritical Lifshitz point. This leaves open the possibility of a controlled experimental investigation into this unusual class of statistical models. We evaluate the correlations of the unsqueezed quadrature using both an exact numerical simulation and a Gaussian approximation, and obtain an accurate numerical calculation of the non-Gaussian correlations.