227 research outputs found
Resonance Superfluidity: Renormalization of Resonance Scattering Theory
We derive a theory of superfluidity for a dilute Fermi gas that is valid when
scattering resonances are present. The treatment of a resonance in many-body
atomic physics requires a novel mean-field approach starting from an
unconventional microscopic Hamiltonian. The mean-field equations incorporate
the microscopic scattering physics, and the solutions to these equations
reproduce the energy-dependent scattering properties. This theory describes the
high- behavior of the system, and predicts a value of which is a
significant fraction of the Fermi temperature. It is shown that this novel
mean-field approach does not break down for typical experimental circumstances,
even at detunings close to resonance. As an example of the application of our
theory we investigate the feasibility for achieving superfluidity in an
ultracold gas of fermionic Li.Comment: 15 pages, 10 figure
Tree-body loss of of trapped ultracold Rb atoms due to a Feshbach resonance
The loss of ultracold trapped atoms in the vicinity of a Feshbach resonance
is treated as a two-stage reaction, using the Breit-Wigner theory. The first
stage is the formation of a resonant diatomic molecule, and the second one is
its deactivation by inelastic collisions with other atoms. This model is
applied to the analysis of recent experiments on Rb, leading to an
estimated value of cms for the deactivation rate
coefficient.Comment: LaTeX, 4 pages with 1 figures, uses REVTeX4, uses improved
experimental dat
Measurement of the Zero Crossing in a Feshbach Resonance of Fermionic 6-Li
We measure a zero crossing in the scattering length of a mixture of the two
lowest hyperfine states of 6-Li. To locate the zero crossing, we monitor the
decrease in temperature and atom number arising from evaporation in a CO2 laser
trap as a function of magnetic field B. The temperature decrease and atom loss
are minimized for B=528(4) G, consistent with no evaporation. We also present
preliminary calculations using potentials that have been constrained by the
measured zero crossing and locate a broad Feshbach resonance at approximately
860 G, in agreement with previous theoretical predictions. In addition, our
theoretical model predicts a second and much narrower Feshbach resonance near
550 G.Comment: Five pages, four figure
Quantum effects on the dynamics of a two-mode atom-molecule Bose-Einstein condensate
We study the system of coupled atomic and molecular condensates within the
two-mode model and beyond mean-field theory (MFT). Large amplitude
atom-molecule coherent oscillations are shown to be damped by the rapid growth
of fluctuations near the dynamically unstable molecular mode. This result
contradicts earlier predictions about the recovery of atom-molecule
oscillations in the two-mode limit. The frequency of the damped oscillation is
also shown to scale as with the total number of atoms ,
rather than the expected pure scaling. Using a linearized model, we
obtain analytical expressions for the initial depletion of the molecular
condensate in the vicinity of the instability, and show that the important
effect neglected by mean field theory is an initially non-exponential
`spontaneous' dissociation into the atomic vacuum. Starting with a small
population in the atomic mode, the initial dissociation rate is sensitive to
the exact atomic amplitudes, with the fastest (super-exponential) rate observed
for the entangled state, formed by spontaneous dissociation.Comment: LaTeX, 5 pages, 3 PostScript figures, uses REVTeX and epsfig,
submitted to Physical Review A, Rapid Communication
Quantum correlated twin atomic beams via photo-dissociation of a molecular Bose-Einstein condensate
We study the process of photo-dissociation of a molecular Bose-Einstein
condensate as a potential source of strongly correlated twin atomic beams. We
show that the two beams can possess nearly perfect quantum squeezing in their
relative numbers.Comment: Corrected LaTeX file layou
Pharmacotherapy review: a proposal to improve medication adherence among hypertensive patients
Serum bactericidal activity as indicator of innate immunity in pacu Piaractus mesopotamicus (Holmberg, 1887)
Searching for an oxygenation event in the fossiliferous Ediacaran of northwestern Canada
Reproductive biology of endemic Solanum melissarum Bohs (Solanaceae) and updating of its current geographic distribution as the basis for its conservation in the Brazilian Cerrado
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