Experimental test of the violation of local realism in quantum mechanics without Bell inequalities

Physical Review A - Atomic, Molecular, and Optical Physics

Volumn 56, Issue 1, 1997, Pages 176-181

  Di Giuseppe, G ^a   De Martini, F ^a   Boschi, D ^a  

^a UNIVERSITÀ DI ROMA LA SAPIENZA   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001144271     PISSN: 10502947     EISSN: 10941622     Source Type: Journal    
DOI: 10.1103/PhysRevA.56.176     Document Type: Article

References (23)

1. A. Einstein, B. Podolsky, and N. Rosen, Phys. Rev. 47, 777 (1935); PHRVAO
2. M. Redhead, Incompleteness, Nonlocality and Realism (Clarendon, Oxford, 1990), Chap. 3.
3. J. S. Bell, Speakable and Unspeakable in Quantum Mechanics (Cambridge University Press, 1987).
4. A. Aspect, P. Grangier, and G. Roger, Phys. Rev. Lett. 47, 460 (1981); PRLTAO
5. A. Aspect, P. Grangier, G. Roger, and J. Dalibard, 49, 1804 (1982).
6. D. M. Greenberger, M. A. Horne, and A. Zeilinger, Am. J. Phys. 58, 1131 (1990).AJPIAS
7. N. D. Mermin, Phys. Rev. Lett. 65, 1838 (1990).PRLTAO
8. A nonlocality proof for two particles with spin-I has been given by P. Heywood and M. L. Redhead, Found. Phys. 13, 481 (1983); FNDPA4
9. H. R. Brown and G. Svetlichny, 20, 1379 (1990).
10. L. Hardy, Phys. Rev. Lett. 71, 1665 (1993).PRLTAO
11. S. Goldstein, Phys. Rev. Lett. 72, 1951 (1994), PRLTAO
12. T. F. Jordan, Phys. Rev. A 50, 62 (1994).PLRAAN
13. J. R. Torgerson, D. Branning, C. H. Monken, and L. Mandel, Phys. Lett. A 204, 323 (1995). PYLAAGWe stress here the necessity of using the state postselection in order to meet with the present experimental scheme the condition of state entanglement, which is required in any nonlocality test: cf. Ref. 1 and S. Popescu, L. Hardy, and M. Zukowsky (unpublished). The nonoptimallity of postselection will be accounted for later in the present paper.
14. This “postselected” π-entanglement two-photon interference process parallels the well known effect due to p-momentum entanglement realized by any normal (nonpolarizing) beam splitter: Y. H. Shih and C. Alley, Phys. Rev. Lett. 61, 2921 (1988); PRLTAO
15. Z. Y. Ou and L. Mandel, 61, 50 (1988).
16. A. Peres, Quantum Theory: Concepts and Methods (Kluwer, Dordrecht, 1995), Chap. 1.
17. Because of this state postselection, implying the nondetection by the system of a relevant number of PDC generated photon pairs and thus a reduced overall quantum efficiency of the apparatus, the present experiment cannot be considered a loophole-free experiment: cf. P. H. Eberhard, Phys. Rev. A 47, 748 (1993); PLRAAN
18. L. De Caro and A. Garuccio, 50, R2803 (1994).
19. Note that the Hardy argument can be transformed into a Bell-type inequality: A. Garuccio, Phys. Rev. A 52, 2535 (1995). PLRAAN
20. Thus far all experiments on the violation of Bell’s-type inequalities have implied the same postselection process encountered here. The only exception is the recent work adopting the method of “direct entanglement” allowed by type-II NL crystals: P. Kwiat, K. Matte, H. Weinfurter, A. Sergienko, A. Zeilinger, and Y. Shih, Phys. Rev. Lett. 75, 4337 (1995); and PRLTAOD. Boschi, F. De Martini, and G. Di Giuseppe in Quantum Interferometry, edited by F. De Martini, G. Denardo, and Y. Shih (VCH Publishing group, Berlin, 1996).
21. While (Formula presented) is independent of any (Q.E.), Δτ is inversely proportional to the product of all (Q.E.)’s involved in the experiment; i.e., related to laser, NL crystal, optics, detectors, etc.
22. R. Horodecki, P. Horodecki, and M. Horodecki, Phys. Lett. A 200, 340 (1995); PYLAAG
23. 210, 223 (1996). A study on mixed states by the present π-entanglement method is now in progress in our laboratory.