The multi-mode character of quantum fields imposes constraints on the implementation of high-fidelity quantum gates between individual photons. So far this has only been studied for the longitudinal degree of freedom. Here we show that effects due to the transverse degrees of freedom significantly affect quantum gate performance. We also discuss potential solutions, in particular separating the two photons in the transverse direction.
@article{arxiv.1006.3584,
title = {Transverse multi-mode effects on the performance of photon-photon gates},
author = {Bing He and Andrew MacRae and Yang Han and A. I. Lvovsky and Christoph Simon},
journal= {arXiv preprint arXiv:1006.3584},
year = {2015}
}