Recoil Free Scattering From a Free Gas

TL;DR

This paper investigates recoil-free scattering in a free gas and its implications for decoherence in atom interferometry, revealing phase shifts without state changes and clarifying the measurement-like effects of scattering.

Contribution

It introduces a recoil-free scattering process that causes phase shifts without changing states, advancing understanding of decoherence in atom interferometers.

Findings

Recoil-free scattering leaves atom and gas states unchanged.

Such scattering induces phase shifts in matter waves.

Clarifies the role of scattering as a which-way measurement.

Abstract

We present a treatment of decoherence in an atom due to scattering from a gas of free particles. We show that there is a recoil free scattering process that leaves both the atom and the gas in an unchanged state, but allows for the acquisition of a phase shift that remains in the free space limit. This is essential to understanding decoherence in a separated arm atom interferometer, where a gas of atoms forms a refractive medium for a matter wave. Our work clarifies the extent to which scattering of a free particle acts as a which-way measurement.