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arXiv:quant-ph/0402048 · Physical Review Letters

Bell-Type Test of Energy-Time Entangled Qutrits

Rob Thew, Antonio Acín, Hugo Zbinden, N. Gisin

Published Jul 2, 2004• 218 citations
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Abstract

We have performed a Bell-type test for energy-time entangled qutrits. A method of inferring the Bell violation in terms of an associated interference visibility is derived. Using this scheme we obtained a Bell value of $2.784\ifmmode\pm\else\textpm\fi{}0.023$, representing a violation of $34\ensuremath{\sigma}$ above the limit for local variables. The scheme has been developed for use at telecom wavelengths and using proven long distance quantum communication architecture to optimize the utility of this high dimensional entanglement resource.

DOI
10.1103/physrevlett.93.010503

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We report a two-photon interference experiment that realizes a postselection-free test of Bell's inequality based on energy-time entanglement. In contrast with all previous experiments of this type, the employed entangled states are obtained without the use of a beam splitter or a short coincidence window to "throw away" unwanted amplitudes. A (95.0\ifmmode\pm\else\textpm\fi{}1.4)% interference fringe visibility is observed, implying a strong violation of the Bell inequality. The scheme is very compact and has demonstrated excellent stability, suggesting that it may be useful, for example, in practical quantum cryptography.