The Experimental Observation of Replica Symmetry Breaking in Random Lasers

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 theoretically revealed by the change in shape of the probability distribution function of an order parameter named the Parisi overlap.

Despite the profound implications in the new physics of complexity, a direct experimental evidence of the Replica Symmetry Breaking transition, in any field of research was never reported.

C. Conti and coworkers show that pulse-to-pulse fluctuations in random lasers, and  a direct measurement of the Parisi overlap, unveil a transition to a glassy light phase in random lasers compatible with a Replica Symmetry Breaking.

This is the first evidence of Replica Symmetry Breaking and the first direct measurement of the Parisi overlap.


N. Ghofraniha, I. Viola, F. Di Maria, G. Barbarella, G. Gigli, L. Leuzzi and C. Conti reported on the first evidence of Replica Symmetry Breaking in Random Lasers by the direct measurement of the Parisi overlap distribution function (arXiv:1407.5428, Nature Communications 2015)


Biomimetic Random Lasers

Biometic random lasers

Living organisms have evolved well-adapted structures and
materials over geological eras. Through evolutional selection,
nature has devised effective solutions to all sorts of complicated
real-world problems and, following Leonardo Da Vinci,
humans have looked at nature to reach answers. The young
field of biomimetics has given rise to new technologies inspired
by nature’s strategy for materials and devices optimized from
the macroscale to the nanoscale.

Neda Ghofraniha, Luca La Volpe, Daniel Van Opdenbosch, Cordt Zollfrank, and Claudio Conti realize a novel random laser device made by biotemplated paper, and demonstrate the control of mode size and interaction. The work was published in Advanced Optical Materials.