We report on a direct measurement of a phase shift on a weak coherent beam by a single Rb-87 atom in a Mach-Zehnder interferometer. A maximum phase shift of about 1 degree is observed experimentally.
@article{arxiv.0905.3734,
title = {Phase shift of a weak coherent beam induced by a single atom},
author = {Syed Abdullah Aljunid and Meng Khoon Tey and Brenda Chng and Timothy Liew and Gleb Maslennikov and Valerio Scarani and Christian Kurtsiefer},
journal= {arXiv preprint arXiv:0905.3734},
year = {2009}
}