Séminaire de l'INPHYNI: Daniel Benedicto --- Kiran Kolluru

A glance into collective effects in saturated, free space, cold atomic clouds (Daniel Benedicto)

Abstract:

Collective effects in cold atomic systems have attracted a lot of attention in the past decades. They appear in a variety of scenarios such as cavity QED systems, atoms trapped in the evanescence field of a waveguide, and also in free space clouds. Modelling such complex systems still remains a challenge, and many times one resorts to linear approximations to keep the complexity of the problem under control, constraining the validity of the theory to the limit of low saturation. I will present here some recent experimental results obtained in the limit of highly saturated systems, and compare it to numerical results given by a mean-field approximation.

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Thermalization and Spectral Transfer in Weakly Integrable Wave Systems (K. Kolluru)

Abstract:
Integrable nonlinear dispersive systems can be either strongly or weakly integrable. While both possess infinitely many conserved quantities, only strongly integrable systems have a complete set, leading to a vanishing wave kinetic equation and no resonant energy transfer. Weakly integrable systems, such as the KP-I equation—which admits a non-trivial three-wave kinetic equation—still allow spectral transfer despite integrability. Numerical simulations and analytical calculations show relaxation toward Rayleigh–Jeans states, with evolution confined to resonance-supported regions for finite initial spectra.