The spectral gap and the dynamical critical exponent of an exact solvable probabilistic cellular automaton

• A cellular automaton related to a diagonal-to-diagonal six-vertex model is proposed.
• We obtained the exact solution of the model and we found the spectral gap.
• The model belongs to the KPZ universality class.

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 a 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 time-evolution 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=32. 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.