Simulating coupled spin systems in "imaginary time" with lasers

Seminar

We first present very large arrays of >1000 lasers with dissipative coupling that generate minimal-loss steady states with phase ordering identical to the ground state of the corresponding (classical) XY spins. For nearest-neighbor negative coupling they generate long-range "anti-ferromagnetic" phase order which reveals "geometric frustration" in certain type of lattices such as the Kagome lattice (and its removal by next-nearest-neighbor interactions). For long range and mean-field coupling they reveal sharp phase transitions, spin-glass states and a small "condensate" fraction even in the presence of significant quenched disorder. Second, arrays of coupled fiber lasers with fluctuating lengths are shown to be a new type of random laser whose phase and power fluctuations agree with extreme value distributions of random matrices. Thirdly, global coupling can be used for real-time wave front shaping through scattering media and for controlling the spatial coherence of a laser!

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