189 research outputs found
Rotational predissociation of extremely weakly bound atom-molecule complexes produced by Feshbach resonance association
We study the rotational predissociation of atom - molecule complexes with
very small binding energy. Such complexes can be produced by Feshbach resonance
association of ultracold molecules with ultracold atoms. Numerical calculations
of the predissociation lifetimes based on the computation of the energy
dependence of the scattering matrix elements become inaccurate when the binding
energy is smaller than the energy width of the predissociating state. We derive
expressions that represent accurately the predissociation lifetimes in terms of
the real and imaginary parts of the scattering length and effective range for
molecules in an excited rotational state. Our results show that the
predissociation lifetimes are the longest when the binding energy is positive,
i.e. when the predissociating state is just above the excited state threshold.Comment: 17 pages, 5 figure
Tunable disorder in a crystal of cold polar molecules
In the present work, we demonstrate the possibility of controlling by an
external field the dynamics of collective excitations (excitons) of molecules
on an optical lattice. We show that a suitably chosen two-species mixture of
ultracold polar molecules loaded on an optical lattice forms a phononless
crystal, where exciton-impurity interactions can be controlled by applying an
external electric field. This can be used for the controlled creation of
many-body entangled states of ultracold molecules and the time-domain quantum
simulation of disorder-induced localization and delocalization of quantum
particles
Inelastic Collisions in an Ultracold quasi-2D Gas
We present a formalism for rigorous calculations of cross sections for
inelastic and reactive collisions of ultracold atoms and molecules confined by
laser fields in quasi-2D geometry. Our results show that the
elastic-to-inelastic ratios of collision cross sections are enhanced in the
presence of a laser confinement and that the threshold energy dependence of the
collision cross sections can be tuned by varying the confinement strength and
external magnetic fields. The enhancement of the elastic-to-inelastic ratios is
inversely proportional to , where is
the kinetic energy and is the oscillation frequency of the trapped
particles in the confinement potential.Comment: 4 pages, 4 figure
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