1,038 research outputs found
Quantum noise reduction using a cavity with a Bose Einstein condensate
We study an optomechanical system in which the collective density excitations
(Bogoliubov modes) of a Bose Einstein condensate (BEC) is coupled to a cavity
field. We show that the optical force changes the frequency and the damping
constant of the collective density excitations of the BEC. We further analyze
the occurrence of normal mode splitting (NMS) due to mixing of the fluctuations
of the cavity field and the fluctuations of the condensate with finite atomic
two-body interaction. The NMS is found to vanish for small values of the
two-body interaction. We further show that the density excitations of the
condensate can be used to squeeze the output quantum fluctuations of the light
beam. This system may serve as an optomechanical control of quantum
fluctuations using a Bose Einstein condensate.Comment: 8 figure
Superfluid properties of a Bose-Einstein condensate in an optical lattice confined in a cavity
Bogoliubov spectrum of a cigar shaped Fermi superfluid in an optical lattice at the BEC-BCS crossover
Transport behaviour of a Bose Einstein condensate in a bichromatic optical lattice
The Bloch and dipole oscillations of a Bose Einstein condensate (BEC) in an
optical superlattice is investigated. We show that the effective mass increases
in an optical superlattice, which leads to localization of the BEC, in
accordance with recent experimental observations [16]. In addition, we find
that the secondary optical lattice is a useful additional tool to manipulate
the dynamics of the atoms.Comment: Modified manuscrip
Multijet Discriminators for New Physics in Leptonic Signals at the LHC
Some of the cleanest signals for new physics in the early runs of the LHC
will involve strongly-produced particles which give rise to multiple leptons by
undergoing cascade decays through weakly-interacting states to stable
particles. Some of the most spectacular final states will involve three or more
leptons, multiple jets and generally missing energy-momentum as well. A triad
of the most interesting models of new physics which induce such signals is
known to consist of (i) supersymmetry with R-parity conservation, (ii) a
universal extra dimension with conservation of KK-parity and (iii) little Higgs
models with conserved T-parity. Similar signals could also arise if the
Standard Model is augmented with a fourth sequential generation of heavy
fermions. We study all these possibilities and show that a judiciously chosen
set of observables, critically involving the number of identifiable jets and
leptons, can collectively provide distinct footprints for each of these models.
In fact, simple pairwise correlation of such observables can enable unambiguous
identification of the underlying model, even with a relatively small data
sample.Comment: 43 pages, LaTex2e, 8 embedded eps figure
Stability of small amplitude normal modes of a Bose-Einstein condensate with a singly quantized vortex confined in an optical lattice
We study the dynamics of a BEC with a singly quantized vortex, placed in the
combined potential of a 1-D (2-D) optical lattice and an axi-symmetric harmonic
trap. A time-dependent variational Lagrangian analysis shows that an optical
lattice helps to stabilize the vortex which in absence of the optical lattice
is unstable. We find that the normal modes are stable only if the depth of the
optical potential is more than a certain critical value. This critical value of
the optical potential depends on the interaction parameter.In general higher
the interaction parameter,lower the value of the optical potential required to
stabilize the vortex. The BEC with the singly quantized vortex is found to be
relatively more unstable in a 2-D optical lattice compared to a 1-D optical
lattice.Comment: Revised version with 11 pages including 1 figur
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