The Origin of the Dynamical Quantum Non-locality
Non-locality is one of the hallmarks of quantum mechanics and is responsible for paradigmatic features such as entanglement[1] and the Aharonov-Bohm effect[2,3]. Non-locality comes in two "flavours": a \emph{kinematic non-locality}-- arising from the structure of the Hilbert space--[4-6] and a \emph{dynamical non-locality}-- arising from the quantum equations of motion--[2,3,5,6]. Despite of its main role in quantum information processing, kinematic non-locality is unable to induce any change in the probability distributions, so that the "action-at-a-distance" cannot manifest[5,6]. Conversely, dynamical non-locality does create explicit changes in probability, though in a "causality-preserving" manner[6,7]. Recently, the origin of the kinematic non-locality was related to the uncertainty principle[8], here we trace the origin of dynamical non-locality to the superposition principle. This relation adds to the more fundamental understanding of the nature of quantum dynamics and allows us to establish and identify how the uncertainty and the superposition principles determine the non-local character of the outcome of a quantum measurement. Thus, dynamical non-locality emerges as the responsible of the breakdown of the dynamical classical realism[9] and therefore, as key feature in the classical-quantum transition. Most importantly, being based on group theoretical and path integral formulations, our formulation admits immediate generalizations and extensions to, e.g., quantum field theory.