Atom laser divergence - art. no. 170403

We measure the angular divergence of a quasicontinuous, rf-outcoupled, free -falling atom laser as a function of the outcoupling frequency. The data ar e compared to a Gaussian-beam model of laser propagation that generalizes t he standard formalism of photonic lasers. Our treatment includes diffractio n, magnetic lensing, and interaction between the atom laser and the condens ate. We find that the dominant source of divergence is the condensate-laser interaction.