Helium - metrology atK. A. H. van Leeuwen1, 2 and W. Vassen1
1 Laser Centre Vrije Universiteit - De Boelelaan 1081 1081 HV Amsterdam, The Netherlands
2 Department of Applied Physics, Eindhoven University of Technology P.O. Box 513, 5600 MB Eindhoven, The Netherlands
received 7 July 2006; accepted in final form 8 September 2006
published online 29 September 2006
An experiment is proposed to excite the "forbidden" - magnetic dipole (M1) transition at in a collimated and slow atomic beam of metastable helium atoms. It is demonstrated that an excitation rate of can be realised with the beam of a 2 W narrow-band telecom fiber laser intersecting the atomic beam perpendicularly. A Doppler-limited sub-MHz spectroscopic linewidth is anticipated. Doppler-free excitation of 2% of trapped and cooled atoms may be realised in a one-dimensional optical-lattice geometry, using the 2 W laser both for trapping and spectroscopy. The very small (8 Hz) natural linewidth of this transition presents an opportunity for accurate tests
42.50.Xa - Optical tests of quantum theory.
31.30.Jv - Relativistic and quantum electrodynamic effects in atoms and molecules.
32.80.-t - Photon interactions with atoms.
© EDP Sciences 2006