Quality factor of a matter-wave beam

TL;DR

This paper introduces a generalized quality factor for dilute matter-wave beams, applicable beyond the paraxial approximation and in complex atom-optical systems, linking beam symmetry and collimation.

Contribution

It proposes a new, generalized quality factor for matter waves that extends previous measures to more complex propagation regimes and optical systems.

Findings

The generalized quality factor characterizes matter-wave beam quality.

Beam symmetry can be exchanged for improved transverse collimation.

The parameter applies to non-paraxial and fully general linear atom-optical systems.

Abstract

Imperfections in dilute atomic beams propagating in the paraxial regime and in potentials of cylindrical symmetry have been characterized experimentally through the measurement of a parameter analogous to a beam quality factor [Riou et al., Phys. Rev. Lett. 96, 070404 (2006)]. We propose a generalization of this parameter, which is suitable to describe dilute matter waves propagating beyond the paraxial regime and in fully general linear atom-optical systems. The presented quality factor shows that the atomic beam symmetry can be traded for a better transverse collimation.