6 research outputs found
Gibbons-Hawking Effect in the Sonic de Sitter Space-Time of an Expanding Bose-Einstein-Condensed Gas
We propose an experimental scheme to observe the Gibbons-Hawking effect in
the acoustic analog of a 1+1-dimensional de Sitter universe, produced in an
expanding, cigar-shaped Bose-Einstein condensate. It is shown that a two-level
system created at the center of the trap, an atomic quantum dot interacting
with phonons, observes a thermal Bose distribution at the de Sitter
temperature.Comment: 4 pages, 2 figures, RevTex4; as publishe
Observer dependence for the phonon content of the sound field living on the effective curved space-time background of a Bose-Einstein condensate
We demonstrate that the ambiguity of the particle content for quantum fields
in a generally curved space-time can be experimentally investigated in an
ultracold gas of atoms forming a Bose-Einstein condensate. We explicitly
evaluate the response of a suitable condensed matter detector, an ``Atomic
Quantum Dot,'' which can be tuned to measure time intervals associated to
different effective acoustic space-times. It is found that the detector
response related to laboratory, ``adiabatic,'' and de Sitter time intervals is
finite in time and nonstationary, vanishing, and thermal, respectively.Comment: 9 pages, 2 figures; references updated, as published in Physical
Review
"Cosmological" quasiparticle production in harmonically trapped superfluid gases
We show that a variety of cosmologically motivated effective quasiparticle
space-times can be produced in harmonically trapped superfluid Bose and Fermi
gases. We study the analogue of cosmological particle production in these
effective space-times, induced by trapping potentials and coupling constants
possessing an arbitrary time dependence. The WKB probabilities for phonon
creation from the superfluid vacuum are calculated, and an experimental
procedure to detect quasiparticle production by measuring density-density
correlation functions is proposed.Comment: 8 pages, 1 figure; references updated, as published in Physical
Review
Vortex liquids and vortex quantum Hall states in trapped rotating Bose gases
We discuss the feasibility of quantum Hall states of vortices in trapped
low-density two-dimensional Bose gases with large particle interactions. For
interaction strengths larger than a critical dimensionless 2D coupling constant
, upon increasing the rotation frequency, the system is shown
to spatially separate into vortex lattice and melted vortex lattice (vortex
liquid) phases. At a first critical frequency, the lattice melts completely,
and strongly correlated vortex and particle quantum Hall liquids coexist in
inner respectively outer regions of the gas cloud. Finally, at a second
critical frequency, the vortex liquid disappears and the strongly correlated
particle quantum Hall state fills the whole sample.Comment: 11 pages, 3 figures; to appear in J. Phys.