Joint temporal density measurements for two-photon state characterization

We demonstrate a technique for characterizing two-photon quantum states based on joint temporal correlation measurements using time-resolved single-photon detection by femtosecond up-conversion. We measure for the first time the joint temporal density of a two-photon entangled state, showing clearly...

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Bibliographic Details
Published in:Physical review letters 2008-10, Vol.101 (15), p.153602-153602, Article 153602
Main Authors: Kuzucu, Onur, Wong, Franco N C, Kurimura, Sunao, Tovstonog, Sergey
Format: Article
Language:English
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Summary:We demonstrate a technique for characterizing two-photon quantum states based on joint temporal correlation measurements using time-resolved single-photon detection by femtosecond up-conversion. We measure for the first time the joint temporal density of a two-photon entangled state, showing clearly the time anticorrelation of the coincident-frequency entangled photon pair generated by ultrafast spontaneous parametric down-conversion under extended phase-matching conditions. The new technique enables us to manipulate the frequency entanglement by varying the down-conversion pump bandwidth to produce a nearly unentangled two-photon state that is expected to yield a heralded single-photon state with a purity of 0.88. The time-domain correlation technique complements existing frequency-domain measurement methods for a more complete characterization of photonic entanglement.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.101.153602