Generating Entangled Two-Photon States with Coincident Frequencies

Abstract

It is shown that parametric downconversion, with a short-duration pump pulse and a long nonlinear crystal that is appropriately phase matched, can produce a frequency-entangled biphoton state whose individual photons are coincident in frequency. Quantum interference experiments which distinguish this state from the familiar time-coincident biphoton state are described.

Revised version (a typo was corrected) as published on PRL