S. Jeffers, S. Roy, J.-P. Vigier, and G. Hunter (eds.), The Present Status of the Quantum Theory of Light, (Kluwer, Holland, 1996), pp. 311-322.


Mladen Pavicic

Max-Planck-AG Nichtklassische Strahlung, Humboldt University of Berlin, D-12484 Berlin, Germany.

Department of Mathematics, University of Zagreb, GF, Kaciceva 26, POB-217, HR-10001 Zagreb, Croatia; mpavicic@faust.irb.hr; http://m3k.grad.hr/pavicic

Abstract. Two previously discovered effects in the intensity interference: a spin--correlation between formerly unpolarized photons and a spin entanglement at-a-distance between photons that nowhere interacted, have been used for a proposal of a new preselection experiment . The experiment puts together two photons from two independent singlets and makes them interfere at an asymmetrical beam splitter. A coincidental detection of two photons emerging from different sides of the beam splitter preselect their pair-companion photons (which nowhere cross each other's path) into a nonmaximal singlet state. The quantum mechanical nonlocality thus proves to be essentially a property of selection. This enables a loophole-free experimental disproof of local hidden-variable theories requiring detection efficiency as low as 67% and an exclusion of all nonlocal hidden-variable theories that rely on some kind of a physical entanglement by means of a common medium.

PACS numbers: 03.65.Bz, 42.50.Wm

Keywords: four photon interferometry, asymmetrical beam splitters, non-maximal singlets, quantum optics, quantum nonlocality, quantum teleportation, loophole-free Bell experiment.