Beam quality of a nonideal atom laser.
We study the propagation of a noninteracting 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 the 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 nonideal atom-laser beam by a generalized M2 factor defined in analogy to photon lasers. Finally we measure this quality factor for different lensing effects.
Riou
J-F
JF
Laboratoire Charles Fabry de l'Institut d'Optique, Centre National de la Recherche Scientifique et Université Paris Sud 11, Bât. 503, Campus Universitaire d'Orsay, 91403 Orsay Cedex, France. Jean-Felix.Riou@iota.u-psud.fr
Guerin
W
W
Le Coq
Y
Y
Fauquembergue
M
M
Josse
V
V
Bouyer
P
P
Aspect
A
A