2008/07/10 by Onur Kuzucu, Franco N. C. Wong, Sunao Kurimura +2 · 1 citation
Computer Science · Physics and Astronomy · #Laser-Matter Interactions and Applications #Neural Networks and Reservoir Computing #Quantum Information and Cryptography #quant-ph
paper · pdf · doi:10.1103/physrevlett.101.153602
4 pages, 5 figures
arxiv created 2008/07/10 · openalex publication_date 2008/10/07 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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.