We introduce a simple experiment involving a double-slit interferometer by which one can learn basic concepts of quantum interference such as which-path marking, quantum erasers, and geometric phases. Each of them exhibits seemingly mysterious phenomena in quantum physics. In our experiment, we use the double-slit interference of visible light with the polarization as an internal state to demonstrate the disappearance of fringes by which-path marking, recovery of interference using quantum erasers, and the rapid shifting of the fringe pattern induced by the geometric phase. We also present a simple theoretical analysis of an interferometer with an internal state.
@article{arxiv.0907.2289,
title = {Observation of geometric phases in quantum erasers},
author = {H. Kobayashi and S. Tamate and T. Nakanishi and K. Sugiyama and M. Kitano},
journal= {arXiv preprint arXiv:0907.2289},
year = {2011}
}