154 research outputs found
Fast bias inversion of a double well without residual particle excitation
We design fast bias inversions of an asymmetric double well so that the
lowest states in each well remain so and free from residual motional
excitation. This cannot be done adiabatically, and a sudden bias switch
produces in general motional excitation. The residual excitation is suppressed
by complementing a predetermined fast bias change with a linear ramp whose
time-dependent slope compensates for the displacement of the wells. The
process, combined with vibrational multiplexing and demultiplexing, can produce
vibrational state inversion without exciting internal states, just by deforming
the trap.Comment: 7 pages, 6 figure
Cold atom dynamics in crossed laser beam waveguides
We study the dynamics of neutral cold atoms in an -shaped crossed-beam
optical waveguide formed by two perpendicular red-detuned lasers of different
intensities and a blue-detuned laser at the corner. Complemented with a
vibrational cooling process this setting works as a one-way device or "atom
diode"
Exploring classically chaotic potentials with a matter wave quantum probe
We study an experimental setup in which a quantum probe, provided by a
quasi-monomode guided atom laser, interacts with a static localized attractive
potential whose characteristic parameters are tunable. In this system,
classical mechanics predicts a transition from a regular to a chaotic behavior
as a result of the coupling between the longitudinal and transverse degrees of
freedom. Our experimental results display a clear signature of this transition.
On the basis of extensive numerical simulations, we discuss the quantum versus
classical physics predictions in this context. This system opens new
possibilities for investigating quantum scattering, provides a new testing
ground for classical and quantum chaos and enables to revisit the
quantum-classical correspondence
Shortcuts to adiabaticity for an ion in a rotating radially-tight trap
We engineer the fast rotation of a quantum particle confined in an
effectively one-dimensional, harmonic trap, for a predetermined rotation angle
and time, avoiding final excitation. Different schemes are proposed with
different speed limits that depend on the control capabilities. We also make
use of trap rotations to create squeezed states without manipulating the trap
frequencies.Comment: 11 pages, 6 figure
Transport of Atom Packets in a Train of Ioffe-Pritchard Traps
We demonstrate transport and evaporative cooling of several atomic clouds in
a chain of magnetic Ioffe-Pritchard traps moving at a low speed (~m/s). The
trapping scheme relies on the use of a magnetic guide for transverse
confinement and of magnets fixed on a conveyor belt for longitudinal trapping.
This experiment introduces a new approach for parallelizing the production of
Bose-Einstein condensates as well as for the realization of a continuous atom
laser
Continuous loading of a non-dissipative atom trap
We study theoretically a scheme in which particles from an incident beam are
trapped in a potential well when colliding with particles already present in
the well. The balance between the arrival of new particles and the evaporation
of particles from the trapped cloud leads to a steady-state that we
characterize in terms of particle number and temperature. For a cigar shaped
potential, different longitudinal and transverse evaporation thresholds can be
chosen. We show that a resonance occur when the transverse evaporation
threshold coincides with the energy of the incident particles. It leads to a
dramatic increase in phase space density with respect to the incident beam.Comment: 7 pages, 2 figure
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