4,199 research outputs found
Quantum Logic for Trapped Atoms via Molecular Hyperfine Interactions
We study the deterministic entanglement of a pair of neutral atoms trapped in
an optical lattice by coupling to excited-state molecular hyperfine potentials.
Information can be encoded in the ground-state hyperfine levels and processed
by bringing atoms together pair-wise to perform quantum logical operations
through induced electric dipole-dipole interactions. The possibility of
executing both diagonal and exchange type entangling gates is demonstrated for
two three-level atoms and a figure of merit is derived for the fidelity of
entanglement. The fidelity for executing a CPHASE gate is calculated for two
87Rb atoms, including hyperfine structure and finite atomic localization. The
main source of decoherence is spontaneous emission, which can be minimized for
interaction times fast compared to the scattering rate and for sufficiently
separated atomic wavepackets. Additionally, coherent couplings to states
outside the logical basis can be constrained by the state dependent trapping
potential.Comment: Submitted to Physical Review
New paradoxical games based on Brownian ratchets
Based on Brownian ratchets, a counter-intuitive phenomenon has recently
emerged -- namely, that two losing games can yield, when combined, a
paradoxical tendency to win. A restriction of this phenomenon is that the rules
depend on the current capital of the player. Here we present new games where
all the rules depend only on the history of the game and not on the capital.
This new history-dependent structure significantly increases the parameter
space for which the effect operates.Comment: 4 pages, 3 eps figures, revte
Propagation of Bose-Einstein condensates in a magnetic waveguide
Gaseous Bose-Einstein condensates of 2-3 million atoms were loaded into a
microfabricated magnetic trap using optical tweezers. Subsequently, the
condensates were released into a magnetic waveguide and propagated 12 mm.
Single-mode propagation was observed along homogeneous segments of the
waveguide. Inhomogeneities in the guiding potential arose from geometric
deformations of the microfabricated wires and caused strong transverse
excitations. Such deformations may restrict the waveguide physics that can be
explored with propagating condensates.Comment: 5 pages, 4 figure
A Storage Ring for Neutral Atoms
We have demonstrated a storage ring for ultra-cold neutral atoms. Atoms with
mean velocities of 1 m/s corresponding to kinetic energies of ~100 neV are
confined to a 2 cm diameter ring by magnetic forces produced by two
current-carrying wires. Up to 10^6 atoms are loaded at a time in the ring, and
7 revolutions are clearly observed. Additionally, we have demonstrated multiple
loading of the ring and deterministic manipulation of the longitudinal velocity
distribution of the atoms using applied laser pulses. Applications of this ring
include large area atom interferometers and cw monochromatic atomic beam
generation.Comment: 4 pages, 5 figure
Bosons in cigar-shape traps: Thomas-Fermi regime, Tonks-Girardeau regime, and between
We present a quantitative analysis of the experimental accessibility of the
Tonks-Girardeau gas in the current day experiments with cigar-trapped alkalis.
For this purpose we derive, using a Bethe anzats generated local equation of
state, a set of hydrostatic equations describing one-dimensional
delta-interacting Bose gases trapped in a harmonic potential. The resulting
solutions cover the_entire range_ of atomic densities.Comment: 4 pages, 4 figure
Regimes of quantum degeneracy in trapped 1D gases
We discuss the regimes of quantum degeneracy in a trapped 1D gas and obtain
the diagram of states. Three regimes have been identified: the BEC regimes of a
true condensate and quasicondensate, and the regime of a trapped gas of Tonks
(gas of impenetrable bosons). The presence of a sharp cross-over to the BEC
regime requires extremely small interaction between particles. We discuss how
to distinguish between true and quasicondensates in phase coherence
experiments.Comment: 4 pages, 1 eps figur
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