Fermionic quantum field theories as probabilistic cellular automata

TL;DR

This paper demonstrates that certain fermionic quantum field theories with interactions can be represented as probabilistic cellular automata, revealing how quantum mechanics can emerge from classical statistical systems.

Contribution

It establishes an explicit equivalence between interacting fermionic quantum field theories and probabilistic cellular automata, including a discretized Thirring model example.

Findings

Probabilistic cellular automata can model interacting fermionic quantum field theories.

Quantum concepts like wave functions and density matrices are useful in describing cellular automata.

Naive continuum limit of the automaton exhibits Lorentz symmetry.

Abstract

A class of fermionic quantum field theories with interactions is shown to be equivalent to probabilistic cellular automata, namely cellular automata with a probability distribution for the initial states. Probabilistic cellular automata on a one-dimensional lattice are equivalent to two - dimensional quantum field theories for fermions. They can be viewed as generalized Ising models on a square lattice and therefore as classical statistical systems. As quantum field theories they are quantum systems. Thus quantum mechanics emerges from classical statistics. As an explicit example for an interacting fermionic quantum field theory we describe a type of discretized Thirring model as a cellular automaton. The updating rule of the automaton is encoded in the step evolution operator that can be expressed in terms of fermionic annihilation and creation operators. The complex structure of quantum mechanics is associated to particle -- hole transformations. The naive continuum limit exhibits Lorentz symmetry. We exploit the equivalence to quantum field theory in order to show how quantum concepts as wave functions, density matrix, non-commuting operators for observables and similarity transformations are convenient and useful concepts for the description of probabilistic cellular automata.