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Free keywords:
Quantum Physics, quant-ph, Condensed Matter, Mesoscale and Nanoscale Physics, cond-mat.mes-hall, Physics, Atomic Physics, physics.atom-ph
Abstract:
We observe effects of collective atomic motion in a one-dimensional optical
lattice coupled to an optomechanical system. In this hybrid atom-optomechanical
system, the lattice light generates a coupling between the lattice atoms as
well as between atoms and a micromechanical membrane oscillator. For large atom
numbers we observe an instability in the coupled system, resulting in
large-amplitude atom-membrane oscillations. We show that this behavior can be
explained by light-mediated collective atomic motion in the lattice, which
arises for large atom number, small atom-light detuning and asymmetric pumping
of the lattice, in agreement with previous theoretical work. The model connects
the optomechanical instability to a phase delay in the global atomic
back-action onto the lattice light, which we observe in a direct measurement.
