Editing Spontaneous parametric down-conversion (section)

== History ==
SPDC was demonstrated as early as 1967 by [[Stephen E. Harris|S. E. Harris]], M. K. Oshman, and [[Robert L. Byer|R. L. Byer]],<ref>{{Cite journal|last1=Harris|first1=S. E.|last2=Oshman|first2=M. K.|last3=Byer|first3=R. L.|date=1967-05-01|title=Observation of Tunable Optical Parametric Fluorescence|url=https://link.aps.org/doi/10.1103/PhysRevLett.18.732|journal=Physical Review Letters|volume=18|issue=18|pages=732–734|doi=10.1103/PhysRevLett.18.732|url-access=subscription}}</ref> as well as by D. Magde and H. Mahr.<ref>{{Cite journal|last1=Magde|first1=Douglas|last2=Mahr|first2=Herbert|date=1967-05-22|title=Study in Ammonium Dihydrogen Phosphate of Spontaneous Parametric Interaction Tunable from 4400 to 16 000 \AA{}|url=https://link.aps.org/doi/10.1103/PhysRevLett.18.905|journal=Physical Review Letters|volume=18|issue=21|pages=905–907|doi=10.1103/PhysRevLett.18.905|url-access=subscription}}</ref> It was first applied to experiments related to [[Coherence (physics)|coherence]] by two independent pairs of researchers in the late 1980s: [[Carroll Alley]] and Yanhua Shih, and [[Rupamanjari Ghosh]] and [[Leonard Mandel]].<ref>Y. Shih and C. Alley, in ''Proceedings of the 2nd Int'l Symposium on Foundations of QM in Light of New Technology'', Namiki et al., eds., Physical Society of Japan, Tokyo, 1986.</ref><ref>{{cite journal | last1 = Ghosh | first1 = R. | last2 = Mandel | first2 = L. | year = 1987 | title = Observation of Nonclassical Effects in the Interference of Two Photons | journal = Phys. Rev. Lett. | volume = 59 | issue = 17| pages = 1903–1905 | doi=10.1103/physrevlett.59.1903| pmid = 10035364 | bibcode = 1987PhRvL..59.1903G }}</ref> The [[Wave–particle duality|duality]] between incoherent ([[Van Cittert–Zernike theorem]]) and biphoton emissions was found.<ref>http://pra.aps.org/abstract/PRA/v62/i4/e043816 - Duality between partial coherence and partial entanglement</ref>