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arXiv · 1306.6641

Long-distance distribution of genuine energy-time entanglement

A. Cuevas·G. Carvacho·G. Saavedra·J. Cariñe·W. A. T. Nogueira·M. Figueroa·A. Cabello·P. Mataloni·G. Lima·G. B. Xavier
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Abstract

Any practical realization of entanglement-based quantum communication must be intrinsically secure and able to span long distances avoiding the need of a straight line between the communicating parties. The violation of Bell's inequality offers a method for the certification of quantum links without knowing the inner workings of the devices. Energy-time entanglement quantum communication satisfies all these requirements. However, currently there is a fundamental obstacle with the standard configuration adopted: an intrinsic geometrical loophole that can be exploited to break the security of the communication, in addition to other loopholes. Here we show the first experimental Bell violation with energy-time entanglement distributed over 1 km of optical fibers that is free of this geometrical loophole. This is achieved by adopting a new experimental design, and by using an actively stabilized fiber-based long interferometer. Our results represent an important step towards long-distance secure quantum communication in optical fibers.

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A. Cuevas, G. Carvacho, G. Saavedra, J. Cariñe, W. A. T. Nogueira, M. Figueroa, A. Cabello, P. Mataloni, G. Lima, G. B. Xavier. 2013-06-27. Long-distance distribution of genuine energy-time entanglement. https://doi.org/10.1038/ncomms3871

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