title: Generating entangled two-photon states with coincident frequencies.
abstract: It is shown that parametric down-conversion, 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.
authors: Massachusetts Institute of Technology, Research Laboratory of Electronics, Cambridge, MA 02139, USA.
authors: Vittorio
authors: V
authors: Giovannetti
authors: Lorenzo
authors: L
authors: Maccone
authors: Jeffrey H
authors: JH
authors: Shapiro
authors: Franco N C
authors: FN
authors: Wong