1107.0178 (Giovanni Vacanti et al.)

Photon production from the vacuum close to the super-radiant transition:
When Casimir meets Kibble-Zurek    [PDF]

Giovanni Vacanti, Stefano Pugnetti, Nicolas Didier, Mauro Paternostro, G. Massimo Palma, Rosario Fazio, Vlatko Vedral

The dynamical Casimir effect (DCE) predicts the generation of photons from
the vacuum due to the parametric amplification of the quantum fluctuation of an
electromagnetic field\cite{casimir1,casimir2}. The verification of such effect
is still elusive in optical systems due to the very demanding requirements of
its experimental implementation. This typically requires very fast changes of
the boundary conditions of the problem, such as the high-frequency driving of
the positions of the mirrors of a cavity accommodating the field. Here, we show
that an ensemble of two-level atoms collectively coupled to the electromagnetic
field of a cavity (thus embodying the quantum Dicke model\cite{dicke}), driven
at low frequencies and close to a quantum phase transition, stimulates the
production of photons from the vacuum. This paves the way to an effective
simulation of the DCE through a mechanism that has recently found an
outstanding experimental demonstration\cite{esslinger}. The spectral properties
of the emitted radiation reflect the critical nature of the system and allow us
to link the detection of DCE to the Kibble-Zurek mechanism for the production
of defects when crossing a continuous phase transition\cite{KZ1,KZ2}. We
illustrate the features of our proposal by addressing a simple cavity
quantum-electrodynamics (cQED) setting of immediate experimental realisation.

View original: http://arxiv.org/abs/1107.0178