8 research outputs found
Integrability breakdown in longitudinaly trapped, one-dimensional bosonic gases
A system of identical bosons with short-range (contact) interactions is
studied. Their motion is confined to one dimension by a tight lateral trapping
potential and, additionally, subject to a weak harmonic confinement in the
longitudinal direction. Finite delay time associated with penetration of
quantum particles through each other in the course of a pairwise
one-dimensional collision in the presence of the longitudinal potential makes
the system non-integrable and, hence, provides a mechanism for relaxation to
thermal equilibrium. To analyse this effect quantitatively in the limit of a
non-degenerate gas, we develop a system of kinetic equations and solve it for
small-amplitude monopole oscillations of the gas. The obtained damping rate is
long enough to be neglected in a realistic cold-atom experiment, and therefore
longitudinal trapping does not hinder integrable dynamics of atomic gases in
the 1D regime
Photoionization of ultracold and Bose-Einstein condensed Rb atoms
Photoionization of a cold atomic sample offers intriguing possibilities to
observe collective effects at extremely low temperatures. Irradiation of a
rubidium condensate and of cold rubidium atoms within a magneto-optical trap
with laser pulses ionizing through 1-photon and 2-photon absorption processes
has been performed. Losses and modifications in the density profile of the
remaining trapped cold cloud or the remaining condensate sample have been
examined as function of the ionizing laser parameters. Ionization
cross-sections were measured for atoms in a MOT, while in magnetic traps losses
larger than those expected for ionization process were measured.Comment: 9 pages, 7 figure