Photon engineering for quantum information processing (pp480-502)
        A.B. U'Ren, K. Banaszek, and I.A. Walmsley
          doi: https://doi.org/10.26421/QIC3.s-3
Abstracts: We study distinguishing information in the context of quantum interference involving more than one parametric downconversion (PDC) source and in the context of generating 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.
Key words: parametric down-conversion, polarization-entanglement, quantum communication, Bell state measurement, optical quantum computing