63 research outputs found
Distillation of Bose-Einstein condensates in a double-well potential
Bose-Einstein condensates of sodium atoms, prepared in an optical dipole
trap, were distilled into a second empty dipole trap adjacent to the first one.
The distillation was driven by thermal atoms spilling over the potential
barrier separating the two wells and then forming a new condensate. This
process serves as a model system for metastability in condensates, provides a
test for quantum kinetic theories of condensate formation, and also represents
a novel technique for creating or replenishing condensates in new locations
Atom interferometry with Bose-Einstein condensates in a double-well potential
A trapped-atom interferometer was demonstrated using gaseous Bose-Einstein
condensates coherently split by deforming an optical single-well potential into
a double-well potential. The relative phase between the two condensates was
determined from the spatial phase of the matter wave interference pattern
formed upon releasing the condensates from the separated potential wells.
Coherent phase evolution was observed for condensates held separated by 13
m for up to 5 ms and was controlled by applying ac Stark shift potentials
to either of the two separated condensates.Comment: 4 pages, 4 figure
Berry-Like Phases in Structured Atoms and Molecules
Quantum mechanical phases arising from a periodically varying Hamiltonian are considered. These phases are derived from the eigenvalues of a stationary, “dressed” Hamiltonian that is able to treat internal atomic or molecular structure in addition to the time variation. In the limit of an adiabatic time variation, the usual Berry phase is recovered. For more rapid variation, nonadiabatic corrections to the Berry phase are recovered in perturbation theory, and their explicit dependence on internal structure emerges. Simple demonstrations of this formalism are given, to particles containing interacting spins, and to molecules in electric fields
Coreless vortex formation in a spinor Bose-Einstein condensate
Coreless vortices were phase-imprinted in a spinor Bose-Einstein condensate.
The three-component order parameter of F=1 sodium condensates held in a
Ioffe-Pritchard magnetic trap was manipulated by adiabatically reducing the
magnetic bias field along the trap axis to zero. This distributed the
condensate population across its three spin states and created a spin texture.
Each spin state acquired a different phase winding which caused the spin
components to separate radially.Comment: 5 pages, 2 figure
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
Transport of Bose-Einstein Condensates with Optical Tweezers
We have transported gaseous Bose-Einstein condensates over distances up to 44
cm. This was accomplished by trapping the condensate in the focus of an
infrared laser and translating the location of the laser focus with controlled
acceleration. Condensates of order 1 million atoms were moved into an auxiliary
chamber and loaded into a magnetic trap formed by a Z-shaped wire. This
transport technique avoids the optical and mechanical access constraints of
conventional condensate experiments and creates many new scientific
opportunities.Comment: 5 pages, 3 figure
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