[Show abstract][Hide abstract] ABSTRACT: We study the effect of different heating rates on a dilute Bose gas
confined in a quasi-1D finite, leaky box. An optical kicked
rotor is used to transfer energy to the atoms while two repulsive
optical beams are used to confine the atoms. The average energy of
the atoms is localized after a large number of kicks and the system
reaches a nonequilibrium steady state. A numerical simulation of the
experimental data suggests that the localization is due to energetic
atoms leaking over the barrier. Our data also indicates a
correlation between collisions and the destruction of the
Bose-Einstein condensate fraction.
Full-text · Article · Aug 2006 · EPL (Europhysics Letters)
[Show abstract][Hide abstract] ABSTRACT: We report an experimental study of quantum transport for atoms confined in a periodic potential and compare between thermal and Bose-Einstein condensation (BEC) initial conditions. We observe ballistic transport for all values of well depth and initial conditions, and the measured expansion velocity for thermal atoms is in excellent agreement with a single-particle model. For weak wells, the expansion of the BEC is also in excellent agreement with single-particle theory, using an effective temperature. We observe a crossover to a new regime for the BEC case as the well depth is increased, indicating the importance of interactions on quantum transport.
Full-text · Article · May 2006 · Physical Review Letters
[Show abstract][Hide abstract] ABSTRACT: We report on an experimental study of recoil-induced resonances
as a method of velocimetry for cold atomic samples.
We present a refined experimental method that greatly improves
the sensitivity of the measurement over previous experiments.
Using frequency-modulation (FM) spectroscopy techniques we achieve
a sensitivity that approaches the shot noise limit.
In addition, we present a novel approach to deriving the line shape
of the observed signal, based on the concept of quantum transport
and tunnelling in motional Bloch bands.
Preview · Article · Aug 2001 · Journal of Optics B Quantum and Semiclassical Optics
[Show abstract][Hide abstract] ABSTRACT: We report the first observation of the quantum Zeno and anti-Zeno effects in an unstable system. Cold sodium atoms are trapped in a far-detuned standing wave of light that is accelerated for a controlled duration. For a large acceleration the atoms can escape the trapping potential via tunneling. Initially the number of trapped atoms shows strong nonexponential decay features, evolving into the characteristic exponential decay behavior. We repeatedly measure the number of atoms remaining trapped during the initial period of nonexponential decay. Depending on the frequency of measurements we observe a decay that is suppressed or enhanced as compared to the unperturbed system.
Preview · Article · Aug 2001 · Physical Review Letters
[Show abstract][Hide abstract] ABSTRACT: We study the motion of ultra-cold atoms in an accelerating optical lattice. We find that the tunneling dynamics are strongly affected by repeated measurement during the non-exponential time, leading to either inhibition (zeno) or enhancement (anti-zeno) of decay.