Editing Spontaneous parametric down-conversion (section)

== Applications ==

SPDC allows for the creation of [[optical field]]s containing (to a good approximation) a single photon.  As of 2005, this is the predominant mechanism for an experimenter to create single photons (also known as [[Fock state]]s).<ref>{{cite journal
 | last1 =Zavatta
 | first1 =Alessandro
 | last2 =Viciani
 | first2 =Silvia
 | last3 =Bellini
 | first3 =Marco
 | title =Tomographic reconstruction of the single-photon Fock state by high-frequency homodyne detection
 | journal =Physical Review A
 | volume =70
 | issue =5
 | pages =053821
 | year =2004
 | doi =10.1103/PhysRevA.70.053821
|arxiv = quant-ph/0406090 |bibcode = 2004PhRvA..70e3821Z | s2cid =119387795
 }}</ref> The single photons as well as the photon pairs are often used in [[quantum information]] experiments and applications like [[quantum cryptography]] and [[Bell test experiments]].

SPDC is widely used to create pairs of entangled photons with a high degree of spatial correlation.<ref name="WalbornMonken2010">{{cite journal |last1=Walborn |first1=S.P. |last2=Monken |first2=C.H. |last3=Pádua|first3=S. |last4=Souto Ribeiro|first4=P.H. |title=Spatial correlations in parametric down-conversion |journal=Physics Reports |volume=495 |issue=4–5 |year=2010 |pages=87–139 |issn=0370-1573 |doi=10.1016/j.physrep.2010.06.003 |arxiv=1010.1236 |bibcode=2010PhR...495...87W |s2cid=119221135 }}</ref> Such pairs are used in [[ghost imaging]], in which information is combined from two light detectors: a conventional, multi-pixel detector that does not view the object, and a single-pixel (bucket) detector that does view the object.