Quantum mechanics for classical transport equations

Abstract

Classical transport equations with probabilistic initial conditions can be viewed as quantum systems. In a discrete version they are probabilistic automata. The time-local probabilistic information is encoded in a classical wave function. Its unitary evolution obeys a Schrödinger equation. Statistical observables are represented by operators which do not commute with the ones associated to classical observables. Examples are functions of the quantum energy or the quantum angular momentum. They are important conserved quantities. We construct a complex functional integral for the quantum system which describes the probabilistic classical transport equation. The characteristic features of quantum mechanics, as the superposition of wave functions, interference, the importance of phases, non-commuting operators or a unitary time evolution, are realized by probabilistic classical transport equations.