Optimizing type-I polarization-entangled photons

Radhika Rangarajan, Michael Goggin, Paul Kwiat

Research output: Contribution to journalArticlepeer-review


Optical quantum information processing needs ultra-bright sources of entangled photons, especially from synchronizable femtosecond lasers and low-cost cw-diode lasers. Decoherence due to timing information and spatial mode-dependent phase has traditionally limited the brightness of such sources. We report on a variety of methods to optimize type-I polarization-entangled sources - the combined use of different compensation techniques to engineer high-fidelity pulsed and cw-diode laser-pumped sources, as well as the first production of polarizationentanglement directly from the highly nonlinear biaxial crystal BiB3O6 (BiBO). Using spatial compensation, we show more than a 400-fold improvement in the phase flatness, which otherwise limits efficient collection of entangled photons from BiBO, and report the highest fidelity to date (99%) of any ultrafast polarization-entanglement source. Our numerical code, available on our website, can design optimal compensation crystals and simulate entanglement from a variety of type-I phasematched nonlinear crystals.

Original languageEnglish (US)
Pages (from-to)18920-18933
Number of pages14
JournalOptics Express
Issue number21
StatePublished - Oct 12 2009

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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