692 research outputs found
Self-organised Limit-Cycles, Chaos and Phase-Slippage with a Superfluid inside an Optical Resonator
We study dynamical phases of a driven Bose-Einstein condensate coupled to the
light field of a high-Q optical cavity. For high field seeking atoms at red
detuning the system is known to show a transition from a spatially homogeneous
steady-state to a self-organized regular lattice exhibiting super-radiant
scattering into the cavity. For blue atom pump detuning the particles are
repelled from the maxima of the light-induced optical potential suppressing
scattering. We show that this generates a new dynamical instability of the
self-ordered phase, leading to the appearance of self-ordered stable
limit-cycles characterized by large amplitude self-sustained oscillations of
both the condensate density and cavity field. The limit-cycles evolve into
chaotic behavior by period doubling. Large amplitude oscillations of the
condensate are accompanied by phase-slippage through soliton nucleation at a
rate which increases by orders of magnitude in the chaotic regime. Different
from a superfluid in a closed setup, this driven dissipative superfluid is not
destroyed by the proliferation of solitons since kinetic energy is removed
through cavity losses.Comment: 4 figure
Exotic quantum phase transitions in a Bose-Einstein condensate coupled to an optical cavity
A new extended Dicke model, which includes atom-atom interactions and a
driving classical laser field, is established for a Bose-Einstein condensate
inside an ultrahigh-finesse optical cavity. A feasible experimental setup with
a strong atom-field coupling is proposed, where most parameters are easily
controllable and thus the predicted second-order superradiant-normal phase
transition may be detected by measuring the ground-state atomic population.
More intriguingly, a novel second-order phase transition from the superradiant
phase to the \textquotedblleft Mott" phase is also revealed. In addition, a
rich and exotic phase diagram is presented.Comment: 4 pages; figures 1 and 3 are modified; topos are correcte
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