30/05/2014, 16:15 — 17:15 — Room P3.10, Mathematics Building
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 [1].
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 [2]. We report on the
observation of spontaneous self-structuring in cold atoms released
from a magneto-optical trap [3]. 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.
References
- H. Ritsch et al. Rev. Mod. Phys. 85, 553–601
(2013)
- E. Tesio et al. Phys. Rev. A 86 031801(R) (2012)
- G. Labeyrie et al. Nature Photon. 8 321–325
(2014)