19,753 research outputs found
States of fermionic atoms in an optical superlattice across a Feshbach resonance
We investigate states of fermionic atoms across a broad Feshbach resonance in
an optical superlattice which allows interaction only among a small number of
lattice sites. The states are in general described by superpositions of atomic
resonating valence bonds and dressed molecules. As one scans the magnetic
field, level crossing is found between states with different symmetry
properties, which may correspond to a quantum phase transition in the many-body
case.Comment: 10 pages, 11 figure
Test of Particle-Assisted Tunneling for Strongly Interacting Fermions in an Optical Superlattice
Fermions in an optical lattice near a wide Feshbach resonance are expected to
be described by an effective Hamiltonian of the general Hubbard model with
particle-assisted tunneling rates resulting from the strong atomic interaction
[Phys. Rev. Lett. 95, 243202 (2005)]. Here, we propose a scheme to
unambiguously test the predictions of this effective Hamiltonian through
manipulation of ultracold atoms in an inhomogeneous optical superlattice. The
structure of the low-energy Hilbert space as well as the particle assisted
tunneling rates can be inferred from measurements of the time-of-flight images.Comment: 4 pages, 4 figure
Enstrophy Dynamics of Stochastically Forced Large-Scale Geophysical Flows
Enstrophy is an averaged measure of fluid vorticity. This quantity is
particularly important in {\em rotating} geophysical flows. We investigate the
dynamical evolution of enstrophy for large-scale quasi-geostrophic flows under
random wind forcing. We obtain upper bounds on the enstrophy, as well as
results establishing its H\"older continuity and describing the small-time
asymptotics
Angular Momentum of a Brane-world Model
In this paper we discuss the properties of the general covariant angular
momentum of a five-dimensional brane-world model. Through calculating the total
angular momentum of this model, we are able to analyze the properties of the
total angular momentum in the inflationary RS model. We show that the
space-like components of the total angular momentum of are all zero while the
others are non-zero, which agrees with the results from ordinary RS model.Comment: 8 pages; accepted by Chinese Physics
Effective low-dimensional Hamiltonian for strongly interacting atoms in a transverse trap
We derive an effective low-dimensional Hamiltonian for strongly interacting
ultracold atoms in a transverse trapping potential near a wide Feshbach
resonance. The Hamiltonian includes crucial information about transverse
excitations in an effective model with renormalized interaction between atoms
and composite dressed molecules. We fix all the parameters in the Hamiltonian
for both one- and two-dimensional cases.Comment: v2: 5 pages, 1 figure; expanded presentation of the formalis
Angular Momentum Conservation Law for Randall-Sundrum Models
In Randall-Sundrum models, by the use of general Noether theorem, the
covariant angular momentum conservation law is obtained with the respect to the
local Lorentz transformations. The angular momentum current has also
superpotential and is therefore identically conserved. The space-like
components of the angular momentum for Randall-Sundrum models are
zero. But the component is infinite.Comment: 10 pages, no figures, accepted by Mod. Phys. Lett.
Approximation of Random Slow Manifolds and Settling of Inertial Particles under Uncertainty
A method is provided for approximating random slow manifolds of a class of
slow-fast stochastic dynamical systems. Thus approximate, low dimensional,
reduced slow systems are obtained analytically in the case of sufficiently
large time scale separation. To illustrate this dimension reduction procedure,
the impact of random environmental fluctuations on the settling motion of
inertial particles in a cellular flow field is examined. It is found that noise
delays settling for some particles but enhances settling for others. A
deterministic stable manifold is an agent to facilitate this phenomenon.
Overall, noise appears to delay the settling in an averaged sense.Comment: 27 pages, 9 figure
Measurement based entanglement under conditions of extreme photon loss
The act of measuring optical emissions from two remote qubits can entangle
them. By demanding that a photon from each qubit reaches the detectors, one can
ensure than no photon was lost. But the failure rate then rises quadratically
with loss probability. In [1] this resulted in 30 successes per billion
attempts. We describe a means to exploit the low grade entanglement heralded by
the detection of a lone photon: A subsequent perfect operation is quickly
achieved by consuming this noisy resource. We require only two qubits per node,
and can tolerate both path length variation and loss asymmetry. The impact of
photon loss upon the failure rate is then linear; realistic high-loss devices
can gain orders of magnitude in performance and thus support QIP.Comment: Contains an extension of the protocol that makes it robust against
asymmetries in path length and photon los
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