Single-Photon Atomic Cooling - Raizen Lab - The University of ...

numbers sufficiently large to quantify. This work serves as the topic of the
next section.
4.3 “Optical Box” Configuration
This section discusses the second major experimental iteration [95].
The major improvement made in this iteration was a change in the construction
of the optical dipole trap. We stopped using the multi-mode ytterbium fiber
lasers (1064 nm) to form an attractive potential and began using the Verdi
V10 (523 nm) to form a repulsive potential to transfer the atoms into. The
initial steps of loading atoms in to the magnetic trap was the same as that
used in the previous section and described in Sec. 4.1.
A thermal cloud of 87 Rb atoms is initially produced in a magneto-
optical trap and then cooled in optical molasses. Subsequently atoms in the
|F = 2〉 hyperfine ground state are loaded into a magnetic quadrupole trap
with a radial field gradient of 75 G/cm. We trap approximately 1.7×10 8 atoms
at a temperature of 90µK in a cloud with a 1/e radius of 550µm.
After the magnetic trap is loaded, an optical dipole trap is positioned
above it. The optical dipole trap originates the Verdi V10 which is split
into three beams. Each beam passes through a dual-frequency acousto-optic
modulator, and the first order deflections are tightly focused in one dimension
to form parallel sheets. Each individual sheet has a 1/e 2 beam waist of 10µm
× 200µm and a power of 0.7 W. The three pairs of sheets are crossed to form
a repulsive “box-like” potential, with dimensions 100 µm × 100 µm × 130 µm
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