Topological classification of dynamical phase transitions

TL;DR

This paper explores how the topology of initial and final Hamiltonians influences dynamical phase transitions in 1D and 2D topological systems, revealing topological protection of non-equilibrium time scales and differences in singularity behavior.

Contribution

It establishes a topological classification of dynamical phase transitions based on the ground state topology of Hamiltonians in 1D and 2D systems, highlighting protected time scales and singularity differences.

Findings

Number of protected time scales in 1D equals the difference in winding numbers.

In 2D, Chern numbers do not determine protected time scales.

Singularities in 2D are only in the first derivative of free energy.

Abstract

Dynamical phase transitions (DPT) are characterized by nonanalytical time evolution of the dynamical free energy. For general 2-band systems in one and two dimensions (eg. SSH model, Kitaev-chain, Haldane model, p+ip superconductor, etc.), we show that the time evolution of the dynamical free energy is crucially affected by the ground state topology of both the initial and final Hamiltonians, implying DPTs when the topology is changed under the quench. Similarly to edge states in topological insulators, DPTs can be classified as being topologically protected or not. In 1D systems the number of topologically protected non-equilibrium time scales are determined by the difference between the initial and final winding numbers, while in 2D no such relation exists for the Chern numbers. The singularities of dynamical free energy in the 2D case are qualitatively different from those of the 1D case, the cusps appear only in the first time derivative.