A Tale of Two Heliums: Triplet and Singlet States for Atom Optics and Precision Measurement
Dr Ken Baldwin
ARC Centre of Excellence for Quantum-Atom Optics, The Australian National University, Canberra.
Wednesday, 9th May 2007, 3.30PM, EN102, Ground floor, Engineering Building, Hawthorn.
Helium has a simple atomic structure which makes it an excellent
test-bed for investigations of QED theory. Most attention has
focused on the singlet state manifold, although the large energy
separation from the ground state to the ~20eV first excited state
presents a challenging task. This seminar will outline some new
developments in precision pulsed laser spectroscopy which it is
hoped will lead to a more accurate determination of the Lamb shift
in the (singlet) helium ground state.
The triplet state manifold is similarly well separated from the ground
state, but the doubly forbidden nature of the 23S1 state means it
is the longest lived of all metastable species with an ~8000s lifetime.
This makes it an ideal candidate for atom optics and BEC experiments
which benefit from the ability to detect single atoms due their large
(~20eV) internal energy.
Finally, there is future potential for experiments which exploit the
properties of both singlet and triplet states for precision
measurement of laser-cooled helium atoms.
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