Anomalous parametric resonance in a spin-1/2 chain: dynamical effects of nontrivial topology

TL;DR

This paper investigates how parametric resonance in a spin-1/2 chain reveals topological properties, showing distinct dynamical behaviors depending on the system's topological phase and modulation parameters.

Contribution

It demonstrates that the dynamical response of a spin-1/2 chain under parametric modulation encodes topological information, linking bulk properties to observable magnetization features.

Findings

In the topological regime, magnetization shows no frequency dispersion.

Near resonance, spatial correlations are suppressed in the topological phase.

The transition between topological and trivial phases is controlled by modulation frequency.

Abstract

Resonant parametric modulation is a major tool of studying magnetic systems. For a spin-1/2 chain in a strong magnetic field, the resulting excitations can be mapped on fermionic excitations in the Kitaev chain. We show that the response to turning on the modulation reveals dynamical bulk aspects of the nontrivial topology of the closed chain. In the topological regime, depending on the turn-on rate, the system displays an absence of frequency dispersion of the time-averaged magnetization and an absence or a suppression of its spatial correlations near resonance. The transition between the topological and trivial regimes is controlled by the modulation frequency.