65 research outputs found
Two-Pulse Atomic Coherent Control (2PACC) Spectroscopy of Eley-Rideal Reactions. An Application of an Atom Laser
A spectroscopic application of the atom laser is suggested. The spectroscopy
termed 2PACC employs the coherent properties of matter-waves from a two pulse
atom laser. These waves are employed to control a gas-surface chemical
recombination reaction. The method is demonstrated for an Eley-Rideal reaction
of a hydrogen or alkali atom-laser pulse where the surface target is an
adsorbed hydrogen atom. The reaction yields either a hydrogen or alkali hydride
molecule. The desorbed gas phase molecular yield and its internal state is
shown to be controlled by the time and phase delay between two atom-laser
pulses. The calculation is based on solving the time-dependent Schrodinger
equation in a diabatic framework. The probability of desorption which is the
predicted 2PACC signal has been calculated as a function of the pulse
parameters.Comment: 29 pages and 11 figure
Effects of relative phase and interactions on atom-laser outcoupling from a double-well Bose-Einstein condensate: Markovian and non-Markovian dynamics
We investigate aspects of the dynamics of a continuous atom-laser scheme
based on the merging of independently formed atomic condensates. Our
theoretical analysis covers the Markovian as well as the non-Markovian
operational regimes, and is based on a semiclassical (mean-field) two-mode
model. The role of the relative phase between the two condensates and the
effect of interatomic interactions on the evolution of the trapped populations
and the distribution of outcoupled atoms are discussed.Comment: to appear in J. Phys.
Enhancement and suppression of spontaneous emission and light scattering by quantum degeneracy
Quantum degeneracy modifies light scattering and spontaneous emission. For
fermions, Pauli blocking leads to a suppression of both processes. In contrast,
in a weakly interacting Bose-Einstein condensate, we find spontaneous emission
to be enhanced, while light scattering is suppressed. This difference is
attributed to many-body effects and quantum interference in a Bose-Einstein
condensate.Comment: 4 pages 1 figur
Topological vortex formation in a Bose-Einstein condensate
Vortices were imprinted in a Bose-Einstein condensate using topological
phases. Sodium condensates held in a Ioffe-Pritchard magnetic trap were
transformed from a non-rotating state to one with quantized circulation by
adiabatically inverting the magnetic bias field along the trap axis. Using
surface wave spectroscopy, the axial angular momentum per particle of the
vortex states was found to be consistent with or , depending
on the hyperfine state of the condensate.Comment: 5 pages, 3 figure
Observation of Superfluid Flow in a Bose-Einstein Condensed Gas
We have studied the hydrodynamic flow in a Bose-Einstein condensate stirred
by a macroscopic object, a blue detuned laser beam, using nondestructive {\em
in situ} phase contrast imaging. A critical velocity for the onset of a
pressure gradient has been observed, and shown to be density dependent. The
technique has been compared to a calorimetric method used previously to measure
the heating induced by the motion of the laser beam.Comment: 4 pages, 5 figure
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