Experimental evidence of replica symmetry breaking in random lasers

TL;DR

This paper provides experimental evidence of replica symmetry breaking in random lasers by analyzing pulse-to-pulse fluctuations and the Parisi overlap, revealing a transition to a glassy light phase.

Contribution

It introduces and measures the Parisi overlap analogue in random lasers, providing the first direct experimental evidence of replica symmetry breaking in this field.

Findings

Distribution function indicates a transition to a glassy phase.

Evidence supports replica symmetry breaking in random lasers.

Experimental results align with spin-glass theory predictions.

Abstract

Spin-glass theory is one of the leading paradigms of complex physics and describes condensed matter, neural networks and biological systems, ultracold atoms, random photonics, and many other research fields. According to this theory, identical systems under identical conditions may reach different states and provide different values for observable quantities. This effect is known as Replica Symmetry Breaking and is revealed by the shape of the probability distribution function of an order parameter named the Parisi overlap. However, a direct experimental evidence in any field of research is still missing. Here we investigate pulse-to-pulse fluctuations in random lasers, we introduce and measure the analogue of the Parisi overlap in independent experimental realizations of the same disordered sample, and we find that the distribution function yields evidence of a transition to a glassy light phase compatible with a replica symmetry breaking.