Imprints of screened dark energy on nonlocal quantum correlations

We investigate how screening mechanisms, reconciling light scalar fields driving cosmic acceleration with local fifth force constraints, can be probed via their impact on nonlocal quantum correlations between entangled spin pairs, whose evolution on a curved background is affected by general relativity (GR) and screened modified gravity effects. We consider a gedanken experiment featuring a pair of massive, spin-1/2 particles orbiting the Earth, evaluating their nonlocal correlations through spin observables associated to the Clauser-Horne-Shimony-Holt (CHSH) inequality. Using a general formalism developed earlier for curved spacetime spin evolution, we compute the effects of screening on the CHSH inequality, finding its degree of violation to be suppressed relative to the flat spacetime case. Applying this formalism to the chameleon, symmetron, and dilaton mechanisms, we identify currently unconstrained regions of parameter space where the screening contribution is comparable to that of GR. While detecting these effects will be challenging, our work provides a proof of principle for testing screened dark energy through quantum nonlocality.