9,410 research outputs found
Quantum and Classical Dynamics of a BEC in a Large-Period Optical Lattice
We experimentally investigate diffraction of a Rb-87 Bose-Einstein condensate
from a 1D optical lattice. We use a range of lattice periods and timescales,
including those beyond the Raman-Nath limit. We compare the results to quantum
mechanical and classical simulations, with quantitative and qualitative
agreement, respectively. The classical simulation predicts that the envelope of
the time-evolving diffraction pattern is shaped by caustics: singularities in
the phase space density of classical trajectories. This behavior becomes
increasingly clear as the lattice period grows.Comment: 7 pages, 6 figure
An Optically Plugged Quadrupole Trap for Bose-Einstein Condensates
We created sodium Bose-Einstein condensates in an optically plugged
quadrupole magnetic trap (OPT). A focused, 532nm laser beam repelled atoms from
the coil center where Majorana loss is significant. We produced condensates of
up to atoms, a factor of 60 improvement over previous work [1],
a number comparable to the best all-magnetic traps, and transferred up to atoms into a purely optical trap. Due to the tight axial
confinement and azimuthal symmetry of the quadrupole coils, the OPT shows
promise for creating Bose-Einstein condensates in a ring geometry
Continuous vortex pumping into a spinor condensate with magnetic fields
We study the mechanisms and the limits of pumping vorticity into a spinor
condensate through manipulations of magnetic (B-) fields. We discover a
fundamental connection between the geometrical properties of the magnetic
fields and the quantized circulation of magnetically trapped atoms, a result
which generalizes several recent experimental and theoretical studies. The
optimal procedures are devised that are capable of continuously increasing or
decreasing a condensate's vorticity by repeating certain two step B-field
manipulation protocols. We carry out detailed numerical simulations that
support the claim that our protocols are highly efficient, stable, and robust
against small imperfections of all types. Our protocols can be implemented
experimentally within current technologies.Comment: 9 pages, 6 figure
The new physiology of vision - Chapter XXVII. The colours of interference
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