Regimes of atomic diffraction: Raman versus Bragg diffraction in retroreflective geometries

TL;DR

This paper compares Raman and Bragg atomic diffraction in retroreflective setups, analyzing efficiency and limitations, and highlights the importance of cold ensembles for optimal performance.

Contribution

It provides a detailed analysis of the transition between Raman and Bragg diffraction regimes in retroreflective geometries, emphasizing the conditions for high efficiency.

Findings

Double Raman diffraction is less efficient for short pulses.

Double diffraction requires cold atomic ensembles for high efficiency.

Transition from Raman to Bragg regimes depends on Doppler detuning.

Abstract

We provide a comprehensive study of atomic Raman and Bragg diffraction when coupling to a pair of counterpropagating light gratings (double diffraction) or to a single one (single diffraction) and discuss the transition from one case to the other in a retroreflective geometry as the Doppler detuning changes. In contrast to single diffraction, double Raman loses its advantage of high diffraction efficiency for short pulses and has to be performed in a Bragg-type regime. Moreover, the structure of double diffraction leads to further limitations for broad momentum distributions on the efficiency of mirror pulses, making the use of (ultra) cold ensembles essential for high diffraction efficiency.