On the experimental violation of Mermin's inequality with imperfect measurements

We investigate theoretically the feasibility of an experimental test of the Bell-type inequality derived by Mermin for correlated spins larger than 1/2. Using the Schwinger representation, we link the output fields of two two-mode squeezers in order to create correlated effective spins between two observers. Spin measurements will be performed by photon-number-resolved photodetection, which has recently come of age. We examine the effect of nonideal detection quantum efficiency---and any other optical loss---on the violation margin of Mermin's inequality. We find that experimental violation is well accessible for spins larger than 1 for quantum efficiencies compatible with the current state of the art.