Glassy behavior of light in random lasers

TL;DR

This paper predicts glassy behavior of light in nonlinear disordered media, indicating slow dynamics and metastable states, using a mean-field spin-glass model and replica symmetry breaking analysis.

Contribution

It introduces a general theoretical framework relating light in disordered nonlinear media to spin-glass models, predicting a replica-symmetry breaking phase transition.

Findings

Prediction of a replica-symmetry breaking phase transition

Identification of mode-locking with glassy phase

General theory applicable to various physical systems

Abstract

A theoretical analysis [Angelani et al., Phys. Rev. Lett. 96, 065702 (2006)] predicts glassy behaviour of light in a nonlinear random medium. This implies slow dynamics related to the presence of many metastable states. We consider very general equations (that also apply to other systems, like Bose-Condensed gases) describing light in a disordered non-linear medium and through some approximations we relate them to a mean-field spin-glass-like model. The model is solved by the replica method, and replica-symmetry breaking phase transition is predicted. The transition describes a mode-locking process in which the phases of the modes are locked to random (history and sample-dependent) values. The results are based on very general theory, and embrace a variety of physical phenomena.