Effect of the unpolarized spin state in spin-correlation measurement of two protons produced in the 12C(d,2He) reaction

In this note we discuss the effect of the unpolarized state in the spin-correlation measurement of the $^1S_0$ two-proton state produced in 12C(d,2He) reaction at the KVI, Groningen. We show that in the presence of the unpolarized state the maximal violation of the CHSH-Bell inequality is lower than the classical limit if the purity of the state is less than $\sim \verb+70$. In particular, for the KVI experiment the violation of the CHSH-Bell inequality should be corrected by a factor $\sim\verb+10$ from the pure $^1S_0$ state.Comment: 6 pages, to appear in J. Phys.

Polarization Correlations of 1S0 Proton Pairs as Tests of Bell and Wigner Inequalities

In an experiment designed to overcome the loophole of observer dependent reality and satisfying the counterfactuality condition, we measured polarization correlations of 1S0 proton pairs produced in 12C(d,2He) and 1H(d,He) reactions in one setting. The results of these measurements are used to test the Bell and Wigner inequalties against the predictions of quantum mechanics.Comment: 8 pages, 4 figure

Testing quantum correlations with nuclear probes

We investigated the feasibility of quantum-correlation measurements in nuclear physics experiments. In the first approach, we measured spin correlations of singlet-spin (S-1(0)) proton pairs, which were generated in H-1(d,He-2) and C-12(d, He-2) nuclear charge-exchange reactions. The experiment was optimized for a clean preparation of the He-2 singlet state and offered a 2pi detection geometry for both protons in the exit channel. Our results confirm the effectiveness of the setup for these studies, despite limitations of a small data sample recorded during the feasibility studies