Publication Type
Journal
Journal Name
Physical Review A
Publication Date
Page Number
023802
Volume
74
Issue
2
Abstract
It is known that photons produced by spontaneous parametric down-conversion (SPDC) can be coupled into optical fibers more efficiently by tightly focusing the pumping field. We find that focusing the pump in type-II down-conversion causes photons of ordinary and extraordinary polarization to acquire very different angular spreads, which amounts to spatial information that distinguishes between the polarization states. Numerical studies predict that the photons collected by a detector or quantum channel will be of predominantly one polarizaton and that the degree of polarization entanglement will be lessened in some cases.
