30/05/2014, 16:15 — 17:15 — Sala P3.10, Pavilhão de Matemática
Pedro Gomes, University of Strathclyde
Optomechanical self-structuring in cold atoms
Optomechanics has attracted a lot of interest recently due to the combined control of light and mechanical modes. Spontaneous optomechanical self-organization was observed in a variety of non-linear systems such as atomic ensembles in a cavity .
We are looking in a single mirror scheme where a single pump beam and a mirror placed after the atomic cloud induce spontaneous self-organization observed on a plane transverse to the beam propagation. Previous investigations that showed continuous symmetry breaking on both translation and rotation relied on spatial modulation on the internal states of the atoms. Recently it was predicted that dipole forces alone could induce the same kind of transverse self-organization based on the atomic density without an intrinsic optical non-linearity . We report on the observation of spontaneous self-structuring in cold atoms released from a magneto-optical trap . Two mechanisms come into play in this experiment: the already known internal states non-linearity and the new optomechanical non-linearity. We identify regimes where each mechanism is dominant as well as the mixed case by comparing the structures in both the pump and in a probe beam sent a few tens of microseconds after pump extinction. In the optomechanical dominant regime, we observe in the probe the dynamical growth and decay of atomic structures in the order of magnitude comparable to the atomic motion at ultracold atoms temperatures.
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