A model independent study of nonlocality with polarization entangled photons

TL;DR

This paper introduces a model-independent approach to studying quantum nonlocality using polarization-entangled photons, avoiding assumptions of local realism and enabling direct mechanical observation of state reduction effects.

Contribution

It proposes a novel, model-independent experimental method to observe nonlocality through mechanical effects in polarization-entangled photons, bypassing traditional Bell inequality tests.

Findings

Mechanical monitoring of photon state reduction is feasible.

Nonlocal effects can be observed without assuming local realism.

The approach provides a direct quantum mechanical demonstration of nonlocality.

Abstract

Nonlocality as a fundamental aspect of quantum mechanics is witnessed by violation of Bell inequality or its variants, for which all relevant studies assume some correlations exhibited by local realistic theories. The strategy of Bell's theorem is to establish some criteria to distinguish local realistic theories from quantum mechanics with respect to the nonlocal nature of entangled systems. Here we propose a model independent study of nonlocality that needs not to assume any local theory since observation of the expected nonlocal effect is straightforward quantum mechanically. Our proposal involves a bipartite polarization-entangled system in which one photon immediately reduces into a circular-polarization (CP) state when its partner at a space-like distance is detected in another CP state. The state reduction of the photon can be mechanically monitored because a CP photon carries angular momentum and exerts a torque on a half-wave plate whose mechanical motion is measurable, which is well described by quantum mechanics and independent of any local realistic assumption.