Is replica symmetry breaking in random lasers a true glass phase?
In plain words
Shot-to-shot fluctuations of random-laser spectra have been read as a sign of a glassy state like that of spin glasses, where many configurations compete. Whether this is a real phase of the coupled light modes or a misreading of ordinary fluctuations is disputed.
Precise statement
The overlap distribution P(q) of shot-to-shot spectral intensity fluctuations in random lasers broadens above threshold, interpreted as replica symmetry breaking in a mean-field spin-glass model of nonlinearly coupled modes (Ghofraniha et al., Nature Communications 2015). Question: does a finite-mode, sparsely coupled, gain-saturated laser model have a thermodynamic replica-symmetry-breaking transition, and does the measured P(q) distinguish it from pump-noise-driven mode competition. An answer is a calculation for realistic mode coupling plus a control experiment that separates the two.
What would settle it
A theory of P(q) for realistic random-laser mode coupling, tested against experiments varying mode number and pump stability.