TY - JOUR A1 - Heuer, A. A1 - Menzel, R. A1 - Milonni, P. W. T1 - Induced Coherence, Vacuum Fields, and Complementarity in Biphoton Generation JF - Physical review letters N2 - It is well established that spontaneous parametric down-conversion with induced coherence across two coupled interferometers results in high-visibility single-photon interference. We describe experiments in which additional photon channels are introduced such that "which-path" information is made possible and the fringe visibility in single-photon interference is reduced in accordance with basic notions of complementarity. However, these additional pathways result in nearly perfect visibility when photons are counted in coincidence. A simplified theoretical model accounts for these observations and attributes them directly to the vacuum fields at the different crystals. Y1 - 2015 U6 - https://doi.org/10.1103/PhysRevLett.114.053601 SN - 0031-9007 SN - 1079-7114 VL - 114 IS - 5 PB - American Physical Society CY - College Park ER -