20 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
A fundamental limit for integrated atom optics with Bose-Einstein condensates
The dynamical response of an atomic Bose-Einstein condensate manipulated by
an integrated atom optics device such as a microtrap or a microfabricated
waveguide is studied. We show that when the miniaturization of the device
enforces a sufficiently high condensate density, three-body interactions lead
to a spatial modulational instability that results in a fundamental limit on
the coherent manipulation of Bose-Einstein condensates.Comment: 6 pages, 3 figure
Persistent currents in a Bose-Einstein condensate in the presence of disorder
We examine bosonic atoms that are confined in a toroidal,
quasi-one-dimensional trap, subjected to a random potential. The resulting
inhomogeneous atomic density is smoothened for sufficiently strong, repulsive
interatomic interactions. Statistical analysis of our simulations show that the
gas supports persistent currents, which become more fragile due to the
disorder.Comment: 5 pages, RevTex, 3 figures, revised version, to appear in JLT
Pseudopotential model of ultracold atomic collisions in quasi-one- and two-dimensional traps
We describe a model for s-wave collisions between ground state atoms in
optical lattices, considering especially the limits of quasi-one and two
dimensional axisymmetric harmonic confinement. When the atomic interactions are
modelled by an s-wave Fermi-pseudopotential, the relative motion energy
eigenvalues can easily be obtained. The results show that except for a bound
state, the trap eigenvalues are consistent with one- and two- dimensional
scattering with renormalized scattering amplitudes. For absolute scattering
lengths large compared with the tightest trap width, our model predicts a novel
bound state of low energy and nearly-isotropic wavefunction extending on the
order of the tightest trap width.Comment: 9 pages, 8 figures; submitted to Phys. Rev.
Luttinger model approach to interacting one-dimensional fermions in a harmonic trap
A model of interacting one--dimensional fermions confined to a harmonic trap
is proposed. The model is treated analytically to all orders of the coupling
constant by a method analogous to that used for the Luttinger model. As a first
application, the particle density is evaluated and the behavior of Friedel
oscillations under the influence of interactions is studied. It is found that
attractive interactions tend to suppress the Friedel oscillations while strong
repulsive interactions enhance the Friedel oscillations significantly. The
momentum distribution function and the relation of the model interaction to
realistic pair interactions are also discussed.Comment: 12 pages latex, 1 eps-figure in 1 tar file, extended Appendix, added
and corrected references, new eq. (53), corrected typos, accepted for PR
Mesoscopic scattering in the half-plane: squeezing conductance through a small hole
We model the 2-probe conductance of a quantum point contact (QPC), in linear
response. If the QPC is highly non-adiabatic or near to scatterers in the open
reservoir regions, then the usual distinction between leads and reservoirs
breaks down and a technique based on scattering theory in the full
two-dimensional half-plane is more appropriate. Therefore we relate conductance
to the transmission cross section for incident plane waves. This is equivalent
to the usual Landauer formula using a radial partial-wave basis. We derive the
result that an arbitrarily small (tunneling) QPC can reach a p-wave channel
conductance of 2e^2/h when coupled to a suitable reflector. If two or more
resonances coincide the total conductance can even exceed this. This relates to
recent mesoscopic experiments in open geometries. We also discuss reciprocity
of conductance, and the possibility of its breakdown in a proposed QPC for atom
waves.Comment: 8 pages, 3 figures, REVTeX. Revised version (shortened), accepted for
publication in PR