Resonant atomic diffraction: real versus imaginary potentials

Abstract

In 1997, Zeilinger's group claimed to have observed atomic diffraction from a purely imaginary potential, that is an absorptive grating, made with resonant light waves. In a 1990 summary of their previous research, Kazantsev et al. stated that the diffraction of atoms from resonant light waves is due to a real potential (a resonant phase grating). We resolve this conflict and argue that absorptive gratings of light do not exist for atoms. Analysis of our metastable argon experiments with resonant 801.7 nm light supports this view. We discuss why these issues are important for understanding transverse momentum conservation in diffraction processes.

Acknowledgements

We thank Tim Gay, Paul Burrow and Kees Uiterwaal for helpful discussions. We gratefully acknowledge the financial support from the National Science Foundation and from the Department of Defense Experimental Program to Stimulate Competitive Research (EPSCoR).