1,038 research outputs found
Quantum Criticality of 1D Attractive Fermi Gas
We obtain an analytical equation of state for one-dimensional strongly
attractive Fermi gas for all parameter regime in current experiments. From the
equation of state we derive universal scaling functions that control whole
thermodynamical properties in quantum critical regimes and illustrate physical
origin of quantum criticality. It turns out that the critical properties of the
system are described by these of free fermions and those of mixtures of
fermions with mass and . We also show how these critical properties of
bulk systems can be revealed from the density profile of trapped Fermi gas at
finite temperatures and can be used to determine the T=0 phase boundaries
without any arbitrariness.Comment: extended version, 9 pages, 7 eps figures, corrections of few typo
First and Second Sound Modes of a Bose-Einstein Condensate in a Harmonic Trap
We have calculated the first and second sound modes of a dilute interacting
Bose gas in a spherical trap for temperatures () and for
systems with to particles. The second sound modes (which exist
only below ) generally have a stronger temperature dependence than the
first sound modes. The puzzling temperature variations of the sound modes near
recently observed at JILA in systems with particles match
surprisingly well with those of the first and second sound modes of much larger
systems.Comment: a shorten version, more discussions are given on the nature of the
second sound. A long footnote on the recent work of Zaremba, Griffin, and
Nikuni (cond-mat/9705134) is added, the spectrum of the (\ell=1, n_2=0) mode
is included in fig.
Eliminating the mean-field shift in multicomponent Bose-Einstein condensates
We demonstrate that the nonlinear mean-field shift in a multi-component
Bose-Einstein condensate may be eliminated by controlling the two-body
interaction coefficients. This modification is achieved by, e.g., suitably
engineering the environment of the condensate. We consider as an example the
case of a two-component condensate in a tightly confining atom waveguide.
Modification of the atom-atom interactions is then achieved by varying
independently the transverse wave function of the two components. Eliminating
the density dependent phase shift in a high-density atomic beam has important
applications in atom interferometry and precision measurement
Quantum Hall Ferromagnets
It is pointed out recently that the quantum Hall states in bilayer
systems behave like easy plane quantum ferromagnets. We study the
magnetotransport of these systems using their ``ferromagnetic" properties and a
novel spin-charge relation of their excitations. The general transport is a
combination of the ususal Hall transport and a time dependent transport with
time average. The latter is due to a phase slippage process in
and is characterized by two topological constants. (Figures will be
provided upon requests).Comment: 4 pages, Revtex, Ohio State Universit
Dual neutral variables and knot solitons in triplet superconductors
In this paper we derive a dual presentation of free energy functional for
spin-triplet superconductors in terms of gauge-invariant variables. The
resulting equivalent model in ferromagnetic phase has a form of a version of
the Faddeev model. This allows one in particular to conclude that spin-triplet
superconductors allow formation of stable finite-length closed vortices (the
knotted solitons).Comment: Replaced with version published in PRL (added a discussion of the
effect of the coupling of the fields {\vec s} and {\vec C} on knot
stability). Latest updates of the paper and miscellaneous links related to
knotted solitons are also available at the homepage of the author
http://www.teorfys.uu.se/PEOPLE/egor/ . Animations of knotted solitons by
Hietarinta and Salo are available at
http://users.utu.fi/h/hietarin/knots/c45_p2.mp
Structure of vortices in two-component Bose-Einstein condensates
We develop a three-dimensional analysis of the phase separation of
two-species Bose-Einstein condensates in the presence of vorticity within the
Thomas-Fermi approximation. We find different segregation features according to
whether the more repulsive component is in a vortex or in a vortex-free state.
An application of this study is aimed at describing systems formed by two
almost immiscible species of rubidium-87 that are commonly used in
Bose-Einstein condensation experiments. In particular, in this work we
calculate the density profiles of condensates for the same conditions as the
states prepared in the experiments performed at JILA [Matthews et al., Phys.
Rev. Lett. 83, 2498 (1999)]Comment: 4 pages, 3 figure
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