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Beam quality of a non-ideal atom laser

J. -F. Riou·W. Guerin·Y. Le Coq·M. Fauquembergue·Philippe Bouyer·V. Josse·Alain Aspect
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Abstract

We study the propagation of a non-interacting atom laser distorted by the strong lensing effect of the Bose-Einstein Condensate (BEC) from which it is outcoupled. We observe a transverse structure containing caustics that vary with the density within the residing BEC. Using WKB approximation, Fresnel-Kirchhoff integral formalism and ABCD matrices, we are able to describe analytically the atom laser propagation. This allows us to characterize the quality of the non-ideal atom laser beam by a generalized M$^2$ factor defined in analogy to photon lasers. Finally we measure this quality factor for different lensing effects.

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J. -F. Riou, W. Guerin, Y. Le Coq, M. Fauquembergue, Philippe Bouyer, V. Josse, Alain Aspect. 2005-11-30. Beam quality of a non-ideal atom laser. https://doi.org/10.1103/physrevlett.96.070404

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