We provide exact results for the dynamics of local-operator entanglement in quantum circuits with two-dimensional wires featuring ultralocal solitons, i.e. single-site operators which, up to a phase, are simply shifted by the time evolution. We classify all circuits allowing for ultralocal solitons and show that only dual-unitary circuits can feature moving ultralocal solitons. Then, we rigorously prove that if a circuit has an ultralocal soliton moving to the left (right), the entanglement of local operators initially supported on even (odd) sites saturates to a constant value and its dynamics can be computed exactly. Importantly, this does not bound the growth of complexity in chiral circuits, where solitons move only in one direction, say to the left. Indeed, in this case we observe numerically that operators on the odd sublattice have unbounded entanglement. Finally, we present a closed-form expression for the local-operator entanglement entropies in circuits with ultralocal solitons moving in both directions. Our results hold irrespectively of integrability.
Cited by 3
Katja Klobas et al., Space-like dynamics in a reversible cellular automaton
SciPost Phys. Core 2, 010 (2020) [Crossref]
Ranjan Modak et al., Entanglement revivals as a probe of scrambling in finite quantum systems
J. Stat. Mech. 2020, 083110 (2020) [Crossref]
Bruno Bertini et al., Scrambling in random unitary circuits: Exact results
Phys. Rev. B 102, 064305 (2020) [Crossref]