2012 BFY Abstract Detail Page
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||Test of Bell's inequality using entangled photons.
||We present a description of an implementation of a Bell's Inequality experiment for our advanced lab course. The Bell inequality describes a measurable quantity that can experimentally determine the validity of a large class of hidden variable theories. The apparatus is based on that described by Dehlinger and Mitchell in which two single photon counters (SPC) in conjunction with optical polarizers are used to examine the correlations between two entangled photons. The entangled state is created by downconverting a 405 nm photon into two 810 nm photons with correlated polarizations. The number of coincidences as detected by two SPCs is then measured as a function of one of the polarizer angles. The resulting curve is then fit to a theoretical equation from which we determine whether the inequality is violated or not. Students adjust the properties of the entangled quantum state by varying the phase and polarization angle of the 405 nm photons. After demonstrating that the appropriate entangled state is produced, the students take data and perform the statistical analysis to show the confidence limit with which hidden variable theories can be rejected. The students have four weeks to master operation of the apparatus, acquire their data, and perform the analysis. Time permitting, the students can do a complete realignment of the optical path with the goal of improving the experimental result.
 Dehlinger and Mitchell, "Entangled photon apparatus for the undergraduate laboratory," Am. J. Phys. 70 (9), 898-902 (2002).
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Stephen H. Irons
Yale University - Department of Physics
217 Prospect Street
Steven K. Lamoreaux. Yale University