Relativity of spacetime ontology: When correlations in space become correlata in time

Abstract

Challenging Mermin's perspective that ``correlations have physical reality; that which they correlate does not'' we argue that correlations and correlata are not fundamentally distinct. These are dual concepts depending on the tensor product decomposition defining subsystems. Since the same quantum states may be either entangled or separable, but with respect to alternative tensor product structures, a spatial correlation in one context can become a temporal correlatum in another, and vice versa. In consequence, 2-qubit states invariant under $V\otimes V$ can be either entangled or unentangled, in conflict with the well known uniqueness theorem about the singlet state, a fact with possible implications for the quantum measurement theory.