We obtained the exact solution of a probabilistic cellular automaton related to the diagonal-to-diagonal transfer matrix of the six-vertex model on a square lattice.The model describes the flow of ants (or particles), traveling on an one-dimensional lattice whose sites are small craters containing sleeping or awake ants (two kinds of particles). We found the Bethe ansatz equations and the spectral gap for the timeevolution operator of the cellular automaton. From the spectral gap we show that in the asymmetric case it belongs to the Kardar-Parisi-Zhang (KPZ) universality class, exhibiting a dynamical critical exponent value z = 3 2 . This result is also obtained from a direct Monte Carlo simulation, by evaluating the lattice-size dependence of the decay time to the stationary state.
I. INTRODUCTIONThe six-vertex model was introduced in 1931 by Pauling in order to explain the residual entropy of the ice at zero temperature. The model turns out to be of great interest for physicists and mathematicians of many-body systems due to its exact integrability [1]. The row-to-row transfer matrix of the six-vertex model is the generating function for an infinite set of commuting non-trivial charges in involution [2]. The anisotropic Heisenberg chain, or the so called XXZ quantum chain, is one of these conserved charges. Actually, a quantum system is integrable whenever its Hamiltonian belongs to an infinite set of commuting arXiv:1507.03552v1 [cond-mat.stat-mech]