A Tale of Two Heliums: Triplet and Singlet States for Atom Optics and Precision Measurement

ARC Centre of Excellence for Quantum-Atom Optics, The Australian National University, Canberra.

Wednesday, 9^th 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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