KTH/Nordita/SU seminar in Theoretical Physics

Bell experiments with energy-time (and time-bin) entanglement

by Prof. Adan Cabello (University of Sevilla)



Aerts et al. [Phys. Rev. Lett. 83, 2872 (1999)] showed that Franson's Bell experiment with energy-time entanglement [Phys. Rev. Lett. 62, 2205 (1989)] does not and cannot violate local realism. Despite this fundamental deficiency, and despite that this defect can be exploited to create a Trojan horse attack in Bell inequality-based quantum cryptography, Franson-type experiments have been extensively used for Bell tests and Bell inequality-based quantum cryptography, and have become standard in quantum optics. We show that Franson's postselection procedure applied to local models can produce any violation of the Bell-CHSH inequality. We then introduce a novel two-photon energy-time (and time-bin) Bell experiment without this defect.