875 research outputs found

### Theory for p-Wave Feshbach Molecules

We determine the physical properties of \emph{p}-wave Feshbach molecules in
doubly spin-polarized $^{40}$K and find excellent agreement with recent
experiments. We show that these molecules have a large probability $Z$ to be in
the closed channel or bare molecular state responsible for the Feshbach
resonance. In the superfluid state this allows for observation of Rabi
oscillations between the molecular and atomic components of the Bose-Einstein
condensed pairs, which contains a characteristic signature of the quantum phase
transition that occurs as a function of applied magnetic field.Comment: Replaced with published versio

### Renormalization Group Theory for the Imbalanced Fermi Gas

We formulate a wilsonian renormalization group theory for the imbalanced
Fermi gas. The theory is able to recover quantitatively well-established
results in both the weak-coupling and the strong-coupling (unitarity) limit. We
determine for the latter case the line of second-order phase transitions of the
imbalanced Fermi gas and in particular the location of the tricritical point.
We obtain good agreement with the recent experiments of Y. Shin {\it et al}.
[Nature {\bf 451}, 689 (2008)].Comment: Replaced with published versio

### Resonances in rotationally inelastic scattering of OH($X^2\Pi$) with helium and neon

We present detailed calculations on resonances in rotationally and spin-orbit
inelastic scattering of OH (X\,^2\Pi, j=3/2, F_1, f) radicals with He and Ne
atoms. We calculate new \emph{ab initio} potential energy surfaces for OH-He,
and the cross sections derived from these surfaces compare favorably with the
recent crossed beam scattering experiment of Kirste \emph{et al.} [Phys. Rev. A
\textbf{82}, 042717 (2010)]. We identify both shape and Feshbach resonances in
the integral and differential state-to-state scattering cross sections, and we
discuss the prospects for experimentally observing scattering resonances using
Stark decelerated beams of OH radicals.Comment: 14 pages, 15 Figure

### Scattering resonances in slow NH${}_3$-He collisions

We theoretically study slow collisions of NH$_3$ molecules with He atoms,
where we focus in particular on the observation of scattering resonances. We
calculate state-to-state integral and differential cross sections for collision
energies ranging from 10${}^{-4}$ cm$^{-1}$ to 130 cm$^{-1}$, using fully
converged quantum close-coupling calculations. To describe the interaction
between the NH${}_3$ molecules and the He atoms, we present a four-dimensional
potential energy surface, based on an accurate fit of 4180 {\it ab initio}
points. Prior to collision, we consider the ammonia molecules to be in their
antisymmetric umbrella state with angular momentum $j=1$ and projection $k=1$,
which is a suitable state for Stark deceleration. We find pronounced shape and
Feshbach resonances, especially for inelastic collisions into the symmetric
umbrella state with $j=k=1$. We analyze the observed resonant structures in
detail by looking at scattering wavefunctions, phase shifts, and lifetimes.
Finally, we discuss the prospects for observing the predicted scattering
resonances in future crossed molecular beam experiments with a
Stark-decelerated NH$_3$ beam.Comment: 17 pages, 12 figure

### Ground states and dynamics of population-imbalanced Fermi condensates in one dimension

By using the numerically exact density-matrix renormalization group (DMRG)
approach, we investigate the ground states of harmonically trapped
one-dimensional (1D) fermions with population imbalance and find that the
Larkin-Ovchinnikov (LO) state, which is a condensed state of fermion pairs with
nonzero center-of-mass momentum, is realized for a wide range of parameters.
The phase diagram comprising the two phases of i) an LO state at the trap
center and a balanced condensate at the periphery and ii) an LO state at the
trap center and a pure majority component at the periphery, is obtained. The
reduced two-body density matrix indicates that most of the minority atoms
contribute to the LO-type quasi-condensate. With the time-dependent DMRG, we
also investigate the real-time dynamics of a system of 1D fermions in response
to a spin-flip excitation.Comment: 20 pages, 15 figures, accepted for publication in New Journal of
Physic

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