Use of vector polarizability to manipulate alkali-metal atoms
Presented by D. Cho, Korea University
AC Stark shift of an alkali-metal atom in a laser beam has a Zeeman-like term, which is pro-
portional to the vector polarizability , in addition to a usual scalar () term. I will discuss a few
experiments using to manipulate ground-state alkali-metal atoms:
(i) When the laser is circularly polarized and properly tuned between the D1 and D2 transitions,
the term vanishes and the Stark shift takes the form of a pure Zeeman shift. We constructed an
optical analog of a magnetic trap and carried out an optical Stern-Gerlach experiment.
(ii) For the atoms in an optical trap, a differential ac Stark shift of a ground-hyperne transition can
be tuned out by adjusting polarization of the trapping eld. By using the magic polarization" for
7Li, we achieved 0.6 Hz linewidth. I will describe how we use the capability to manipulate atoms
in an optical lattice in a site-specic manner.
(iii) In a circularly-polarized optical trap, hyperne-transition frequency of an atom depends on the
vibrational quantum number n. I will describe our experiments to develop new schemes to cool
optically trapped atoms using the n-dependence: RF-induced evaporative cooling in an optical
trap and motion-selective" CPT cooling which is analogous to the velocity-selective CPT cooling.
4:00 pm, Wednesday, August 21, 2019
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