Interpreting the macroscopic pointer by analyzing the Einstein-Podolsky-Rosen steering of an entangled macroscopic superposition state

Abstract: We examine Einstein-Podolsky-Rosen's (EPR) steering nonlocality for two realisable Schrodinger cat-type states where a meso/ macroscopic system (called the "cat"-system) is entangled with a spin-$1/2$ system. For large cat-systems, we show that a local hidden state model is near-satisfied, meaning that the cat-system can be consistent with being in a mixture of "dead" and "alive" states despite that it is entangled with the spin system. We justify that a rigorous signature of the Schrodinger cat-type paradox is the EPR-steering of the cat-system and provide two experimental signatures. This leads to a hybrid quantum/ classical interpretation of the macroscopic pointer of a measurement device and suggests many Schrodinger cat-type paradoxes can be explained by microscopic nonlocality.