Field and density coherence of matter-wave fields

TL;DR

This paper explores different types of atomic coherence in matter-wave fields, analyzing how various measurement methods influence coherence properties and their implications for Bose-Einstein condensation and atom lasers.

Contribution

It introduces new definitions of electronic, density, and field coherence tailored to specific measurement types and examines their roles in matter-wave phenomena.

Findings

Different coherence types correspond to specific measurement methods.

Elastic collisions affect the coherence properties of atom lasers.

Descriptions of Bose-Einstein condensation rely on implicit coherence assumptions.

Abstract

In analogy to Glauber's analysis of optical coherence, we adopt an operational approach to introduce different classes of atomic coherence associated with different types of measurements. For the sake of concreteness we consider specifically fluorescence, nonresonant imaging, and ionization. We introduce definitions of coherence appropriate to them, which we call electronic, density, and field coherence, respectively. We illustrate these concepts in various descriptions of Bose-Einstein condensation, showing that each of these descriptions makes different implicit assumptions on the coherence of the system. We also study the impact of elastic collision on the field and density coherence properties of atom lasers.