2,298 research outputs found
Bichromatic Slowing of Metastable Helium
We examine two approaches for significantly extending the velocity range of
the optical bichromatic force (BCF), to make it useful for laser deceleration
of atomic and molecular beams. First, we present experimental results and
calculations for BCF deceleration of metastable helium using very large BCF
detunings, and discuss the limitations of this approach. We consider in detail
the constraints, both inherent and practical, that set the usable upper limit
of the BCF. We then show that a more promising approach is to utilize a BCF
profile with a relatively small velocity range in conjunction with chirped
Doppler shifts, to keep the force resonant with the atoms as they are slowed.
In an initial experimental test of this chirped BCF method, helium atoms are
slowed by m/s using a BCF profile with a velocity width of m/s. Straightforward scaling of the present results indicates that a
decelerator for He* capable of loading a magneto-optical trap (MOT) can yield a
brightness comparable to a much larger Zeeman slower.Comment: 11 pages, 9 figures. Published in Phys. Rev.
Isotropic Light vs Six-Beam Molasses for Doppler Cooling of Atoms From Background Vapor - Theoretical Comparison
We present a 3D theoretical comparison between the radiation-pressure forces
exerted on an atom in an isotropic light cooling scheme and in a six-beam
molasses. We demonstrate that, in the case of a background vapor where all the
space directions of the atomic motion have to be considered, the mean cooling
rate is equal in both configurations. Nevertheless, we also point out what
mainly differentiates the two cooling techniques: the force component
orthogonal to the atomic motion. If this transverse force is always null in the
isotropic light case, it can exceed the radiation-pressure-force longitudinal
component in the six-beam molasses configuration for high atomic velocities,
hence reducing the velocity capture range.Comment: 10 pages, 8 figure
Deflection of barium monofluoride molecules using the bichromatic force: A density-matrix simulation
A full density-matrix simulation is performed for optical deflection of a
barium monofluoride (BaF) beam using the bichromatic force,
which employs pairs of counter-propagating laser beams that are offset in
frequency. We show that the force is sufficient to separate BaF molecules from
the other products generated in a helium-buffer-gas-cooled ablation source. For
our simulations, the density-matrix and force equations are numerically
integrated during the entire time that the molecules pass through a laser beam
to ensure that effects of the evolution of the Doppler shift and of the optical
intensity and phase at the position of the molecule are properly included. The
results of this work are compared to those of a deflection scheme (Phys. Rev. A
107, 032811 (2023)) which uses pulses to drive frequency-resolved
transitions. This work is part of an effort by the EDM collaboration to
measure the electric dipole moment of the electron using BaF molecules embedded
in a cryogenic argon solid. Separation of BaF molecules will aid in producing a
sufficiently pure solid.Comment: 8 pages, 5 figure
Prospects for rapid deceleration of small molecules by optical bichromatic forces
We examine the prospects for utilizing the optical bichromatic force (BCF) to
greatly enhance laser deceleration and cooling for near-cycling transitions in
small molecules. We discuss the expected behavior of the BCF in near-cycling
transitions with internal degeneracies, then consider the specific example of
decelerating a beam of calcium monofluoride molecules. We have selected CaF as
a prototype molecule both because it has an easily-accessible near-cycling
transition, and because it is well-suited to studies of ultracold molecular
physics and chemistry. We also report experimental verification of one of the
key requirements, the production of large bichromatic forces in a multi-level
system, by performing tests in an atomic beam of metastable helium.Comment: 11 pages, 6 figures, revised version, to be published in Physical
Review
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