9 research outputs found
Imaginary Potential Induced Quantum Coherence for Bose-Einstein Condensates
The role of complex potentials in single-body Schr\H{o}dinger equation has
been studied intensively. We study the quantum coherence for degenerate Bose
gases in complex potentials, when the exchange symmetry of identical bosons is
considered. For initially independent Bose-Einstein condensates, it is shown
that even very weak imaginary potential can induce perfect quantum coherence
between different condensates. The scheme to observe imaginary potential
induced quantum coherence is discussed.Comment: 4 pages, 4 figure
Observation of Nonspreading Wave Packets in an Imaginary Potential
We propose and experimentally demonstrate a method to prepare a nonspreading
atomic wave packet. Our technique relies on a spatially modulated absorption
constantly chiseling away from an initially broad de Broglie wave. The
resulting contraction is balanced by dispersion due to Heisenberg's uncertainty
principle. This quantum evolution results in the formation of a nonspreading
wave packet of Gaussian form with a spatially quadratic phase. Experimentally,
we confirm these predictions by observing the evolution of the momentum
distribution. Moreover, by employing interferometric techniques, we measure the
predicted quadratic phase across the wave packet. Nonspreading wave packets of
this kind also exist in two space dimensions and we can control their amplitude
and phase using optical elements.Comment: 4 figure
Optimal atomic detection by control of detuning and spatial dependence of laser intensity
Atomic detection by fluorescence may fail because of reflection from the
laser or transmission without excitation. The detection probability for a given
velocity range may be improved by controlling the detuning and the spatial
dependence of the laser intensity. A simple optimization method is discussed
and exemplified