We study distinguishing information in the context of quantum interference involving more than one parametric downconversion (PDC) source and in the context of polarization-entangled photon pairs based on PDC. We arrive at specific design criteria for two-photon sources so that when used as part of complex optical systems, such as photon-based quantum information processing schemes, distinguishing information between the photons is eliminated guaranteeing high visibility interference. We propose practical techniques which lead to suitably engineered two-photon states that can be realistically implemented with available technology. Finally, we study an implementation of the nonlinear-sign shift (NS) logic gate with PDC sources and show the effect of distinguishing information on the performance of the gate.
@article{arxiv.quant-ph/0305192,
title = {Photon engineering for quantum information processing},
author = {A. B. U'Ren and K. Banaszek and I. A. Walmsley},
journal= {arXiv preprint arXiv:quant-ph/0305192},
year = {2007}
}
Comments
23 pages, 13 figures. submitted to Quantum Information & Computation