Confinement and false vacuum decay on the Potts quantum spin chain

TL;DR

This paper studies non-equilibrium dynamics in the three-state Potts quantum chain after quenches, revealing rich phenomena including confinement, Bloch oscillations, and baryonic excitations, with novel partial localization effects.

Contribution

It provides a detailed analysis of confinement and dynamical phenomena in the Potts chain, highlighting new baryonic excitations and partial localization effects not seen in simpler models.

Findings

Identification of baryonic excitations in quench spectroscopy

Observation of dynamical confinement and Bloch oscillations

Partial localization with unsuppressed light-cone correlations

Abstract

We consider non-equilibrium dynamics after quantum quenches in the mixed-field three-state Potts quantum chain in the ferromagnetic regime. Compared to the analogous setting for the Ising spin chain, the Potts model has a much richer phenomenology, which originates partly from baryonic excitations in the spectrum and partly from the various possible relative alignments of the initial magnetisation and the longitudinal field. We obtain the excitation spectrum by combining semi-classical approximation and exact diagonalisation, and we use the results to explain the various dynamical behaviours we observe. Besides recovering dynamical confinement, as well as Wannier-Stark localisation due to Bloch oscillations similar to the Ising chain, a novel feature is the presence of baryonic excitations in the quench spectroscopy. In addition, when the initial magnetisation and the longitudinal field are misaligned, both confinement and Bloch oscillations only result in partial localisation, with some correlations retaining an unsuppressed light-cone behaviour together with a corresponding growth of entanglement entropy.