Dresden 2011 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 15: Poster 1: Quanteninformation, Quanteneffekte, Laserentwicklung, Laseranwendungen, Ultrakurze Pulse, Photonik

Q 15.80: Poster

Monday, March 14, 2011, 16:30–19:30, P1

Storing the collective positronium atoms with laser field — •Ni Cui, Mihai Macovei, Karen Z. Hatsagortsyan, and Christoph H. Keitel — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

Different from ordinary atoms, positronium(Ps) atoms in the ground states are unstable, and annihilate by γ emission. Populating the excited states of Ps atoms is an efficient way to increase the annihilation lifetime with resonant excitation by laser field [1]. If the inter-particle intervals among Ps atoms is small on a scale given by the relevant transition wavelength, collective effects have large influence on the annihilation probabilities in an assembly of Ps atoms. The numerical results show that, both superradiance and subradiance phenomena are present in the cooperative spontaneous evolutions of two-state (1S-2P) Ps atoms with initially suitable preparation by optical pumping. Then, for the collective three-state (1S-2P-3D) Ps atoms excited by resonant laser field, we find that the Ps atoms could be stored in the upper state with an extended lifetime by a factor much longer than independent Ps atoms.

[1] F. H. M. Faisal and P. S. Ray, J Phys. B: At. Mol. Phys. 14, L715 (1981); A. Karlson and M. H. Mittleman, J Phys. B: At. Mol. Phys. 29, 4609 (1996).