622 research outputs found
Interference of a Tonks-Girardeau Gas on a Ring
We study the quantum dynamics of a one-dimensional gas of impenetrable bosons
on a ring, and investigate the interference that results when an initially
trapped gas localized on one side of the ring is released, split via an
optical-dipole grating, and recombined on the other side of the ring. Large
visibility interference fringes arise when the wavevector of the optical dipole
grating is larger than the effective Fermi wavevector of the initial gas.Comment: 7 pages, 3 figure
Ground state properties of a one-dimensional condensate of hard core bosons in a harmonic trap
The exact N-particle ground state wave function for a one-dimensional
condensate of hard core bosons in a harmonic trap is employed to obtain
accurate numerical results for the one-particle density matrix, occupation
number distribution of the natural orbitals, and momentum distribution. Our
results show that the occupation of the lowest orbital varies as N^{0.59}, in
contrast to N^{0.5} for a spatially uniform system, and N for a true BEC.Comment: 10 pages, 6 figures, submitted to Phys. Rev.
Low-density, one-dimensional quantum gases in a split trap
We investigate degenerate quantum gases in one dimension trapped in a
harmonic potential that is split in the centre by a pointlike potential. Since
the single particle eigenfunctions of such a system are known for all strengths
of the central potential, the dynamics for non-interacting fermionic gases and
low-density, strongly interacting bosonic gases can be investigated exactly
using the Fermi-Bose mapping theorem. We calculate the exact many-particle
ground-state wave-functions for both particle species, investigate soliton-like
solutions, and compare the bosonic system to the well-known physics of Bose
gases described by the Gross-Pitaevskii equation. We also address the
experimentally important questions of creation and detection of such states.Comment: 7 pages, 5 figure
Stability of spinor Fermi gases in tight waveguides
The two and three-body correlation functions of the ground state of an
optically trapped ultracold spin-1/2 Fermi gas (SFG) in a tight waveguide (1D
regime) are calculated in the plane of even and odd-wave coupling constants,
assuming a 1D attractive zero-range odd-wave interaction induced by a 3D p-wave
Feshbach resonance, as well as the usual repulsive zero-range even-wave
interaction stemming from 3D s-wave scattering. The calculations are based on
the exact mapping from the SFG to a ``Lieb-Liniger-Heisenberg'' model with
delta-function repulsions depending on isotropic Heisenberg spin-spin
interactions, and indicate that the SFG should be stable against three-body
recombination in a large region of the coupling constant plane encompassing
parts of both the ferromagnetic and antiferromagnetic phases. However, the
limiting case of the fermionic Tonks-Girardeau gas (FTG), a spin-aligned 1D
Fermi gas with infinitely attractive p-wave interactions, is unstable in this
sense. Effects due to the dipolar interaction and a Zeeman term due to a
resonance-generating magnetic field do not lead to shrinkage of the region of
stability of the SFG.Comment: 5 pages, 6 figure
Pfaffian-like ground state for 3-body-hard-core bosons in 1D lattices
We propose a Pfaffian-like Ansatz for the ground state of bosons subject to
3-body infinite repulsive interactions in a 1D lattice. Our Ansatz consists of
the symmetrization over all possible ways of distributing the particles in two
identical Tonks-Girardeau gases. We support the quality of our Ansatz with
numerical calculations and propose an experimental scheme based on mixtures of
bosonic atoms and molecules in 1D optical lattices in which this Pfaffian-like
state could be realized. Our findings may open the way for the creation of
non-abelian anyons in 1D systems
Measurement of one-particle correlations and momentum distributions for trapped 1D gases
van Hove's theory of scattering of probe particles by a macroscopic target is
generalized so as to relate the differential cross section for atomic ejection
via stimulated Raman transitions to one-particle momentum-time correlations and
momentum distributions of 1D trapped gases. This method is well suited to
probing the longitudinal momentum distributions of 1D gases in situ, and
examples are given for bosonic and fermionic atoms.Comment: 4 pages, 2 .eps figure
Ultracold atoms in one-dimensional optical lattices approaching the Tonks-Girardeau regime
Recent experiments on ultracold atomic alkali gases in a one-dimensional
optical lattice have demonstrated the transition from a gas of soft-core bosons
to a Tonks-Girardeau gas in the hard-core limit, where one-dimensional bosons
behave like fermions in many respects. We have studied the underlying many-body
physics through numerical simulations which accommodate both the soft-core and
hard-core limits in one single framework. We find that the Tonks-Girardeau gas
is reached only at the strongest optical lattice potentials. Results for
slightly higher densities, where the gas develops a Mott-like phase already at
weaker optical lattice potentials, show that these Mott-like short range
correlations do not enhance the convergence to the hard-core limit.Comment: 4 pages, 3 figures, replaced with published versio
Many-body solitons in a one-dimensional condensate of hard core bosons
A mapping theorem leading to exact many-body dynamics of impenetrable bosons
in one dimension reveals dark and gray soliton-like structures in a toroidal
trap which is phase-imprinted. On long time scales revivals appear that are
beyond the usual mean-field theory
Temperature dependence of density profiles for a cloud of non-interacting fermions moving inside a harmonic trap in one dimension
We extend to finite temperature a Green's function method that was previously
proposed to evaluate ground-state properties of mesoscopic clouds of
non-interacting fermions moving under harmonic confinement in one dimension. By
calculations of the particle and kinetic energy density profiles we illustrate
the role of thermal excitations in smoothing out the quantum shell structure of
the cloud and in spreading the particle spill-out from quantum tunnel at the
edges. We also discuss the approach of the exact density profiles to the
predictions of a semiclassical model often used in the theory of confined
atomic gases at finite temperature.Comment: 7 pages, 4 figure
Bose-Einstein Condensation in Geometrically Deformed Tubes
We show that Bose-Einstein condensate can be created in quasi-one-dimensional
systems in a purely geometrical way, namely by bending or other suitable
deformation of a tube.Comment: RevTex, 4pages, no figure
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