3 research outputs found
On the specific heat of a fermionic atomic cloud in the unitary regime
In the unitary regime, when the scattering amplitude greatly exceeds in
magnitude the average inter-particle separation, and below the critical
temperature thermal properties of an atomic fermionic cloud are governed by the
collective modes, specifically the Bogoliubov-Anderson sound modes. The
specific heat of an atomic cloud in a elongated trap in particular has a rather
compex temperature dependence, which changes from an exponential behavior at
very low temperatures (), to for
and then continuosly to at temperatures just below the critical temperature, when the surface
modes play a dominant role. Only the low () and high () temperature
power laws are well defined. For the intermediate temperatures one can
introduce at most a gradually increasing with temperature exponent.Comment: 4 page
Ground-state van der Waals forces in planar multilayer magnetodielectrics
Within the frame of lowest-order perturbation theory, the van der Waals
potential of a ground-state atom placed within an arbitrary dispersing and
absorbing magnetodielectric multilayer system is given. Examples of an atom
situated in front of a magnetodielectric plate or between two such plates are
studied in detail. Special emphasis is placed on the competing attractive and
repulsive force components associated with the electric and magnetic matter
properties, respectively, and conditions for the formation of repulsive
potential walls are given. Both numerical and analytical results are presented.Comment: 16 pages, 8 figures, minor correction
Phase transition from straight into twisted vortex-lines in dipolar Bose-Einstein condensates
The non-local non-linearity introduced by the dipole-dipole interaction plays
a crucial role in the physics of dipolar Bose-Einstein condensates. In
particular, it may distort significantly the stability of straight vortex lines
due to the rotonization of the Kelvin-wave spectrum. In this paper we analyze
this instability showing that it leads to a second-order-like phase transition
from a straight vortex-line into novel helical or snake-like configurations,
depending on the dipole orientation.Comment: 11 pages, 6 figures, Accepted for publication in New J. Phy