Lyapunov exponents and entanglement entropy transition on the noncommutative hyperbolic plane

TL;DR

This paper investigates how noncommutativity and magnetic fields influence quantum dynamics on hyperbolic spaces, revealing a phase transition that suppresses exponential operator growth and affects entanglement entropy.

Contribution

It demonstrates a first-order transition in quantum dynamics on noncommutative hyperbolic planes caused by magnetic fields, contrasting with commutative cases, and introduces a solvable bosonic model.

Findings

Transition suppresses exponential divergence of operator growth

Entanglement entropy vanishes beyond critical magnetic field

Introduces a solvable bosonic model for the algebraic structure

Abstract

We study quantum dynamics on noncommutative spaces of negative curvature, focusing on the hyperbolic plane with spatial noncommutativity in the presence of a constant magnetic field. We show that the synergy of noncommutativity and the magnetic field tames the exponential divergence of operator growth caused by the negative curvature of the hyperbolic space. Their combined effect results in a first-order transition at a critical value of the magnetic field in which strong quantum effects subdue the exponential divergence for {\it all} energies, in stark contrast to the commutative case, where for high enough energies operator growth always diverge exponentially. This transition manifests in the entanglement entropy between the `left' and `right' Hilbert spaces of spatial degrees of freedom. In particular, the entanglement entropy in the lowest Landau level vanishes beyond the critical point. We further present a non-linear solvable bosonic model that realizes the underlying algebraic structure of the noncommutative hyperbolic plane with a magnetic field.