We experimentally observed nonlinear variations in the three-vertex geometric phase in a two- photon polarization qutrit. The three-vertex geometric phase is defined by three quantum states, which generally forms a three-state (qutrit) system. By changing one of the three constituent states, we observed two rapid increases in the three-vertex geometric phase. The observed variations are inherent in a three-state system and cannot be observed in a two-state system. We used a time-reversed two-photon interferometer to measure the geometric phase with much more intense signals than those of a typical two-photon interferometer.
@article{arxiv.1504.01838,
title = {Observation of nonlinear variations in three-vertex geometric phase in two-photon polarization qutrit},
author = {Kazuhisa Ogawa and Shuhei Tamate and Hirokazu Kobayashi and Toshihiro Nakanishi and Masao Kitano},
journal= {arXiv preprint arXiv:1504.01838},
year = {2015}
}