We have performed a test of local realism using entangled photons produced by spontaneous parametric downconversion. This experiment is based on an idea originally proposed by Hardy for a test of local realism without inequalities [4,5], although our experiment actually measures an inequality (as any experiment must.) We find an over 70 standard deviation violation of the predictions of local realism. The experimental effort required for this test is essentially the same as that required for a test of a Bell inequality; however, this test is based on concepts that are easier to understand and more compelling than those behind the original Bell inequality.

·
Slides of a
presentation

A copy of a talk (aimed at a nontechnical audience) describing the basic idea
behind the experiment. This talk uses
the analogy of students observing the color of their professors’ clothing to
describe the experiment. There are no
details about our experiment here.

·
Reprint

J. A. Carlson, M. D. Olmstead, and M. Beck “Quantum
mysteries tested: An experiment implementing Hardy’s test of local realism,”
Am. J. Phys. **74**. 180-186 (2006).

·
For suggestions on improving entanglement using dispersion
precompensation please see the updates
page.

[4] L. Hardy, ‘‘Nonlocality for two particles without inequalities for
almost all entangled states,’’ Phys. Rev. Lett. 71, 1665–1668 (1993).

[5] P. G. Kwiat and L. Hardy, “The mystery of the
quantum cakes,” Am. J. Phys. 68, 33-36 (2000).

webpage updated 6/24/09

*beckmk
at whitman.edu* (replace "at" with @)