Quantum Metric Unveils Defect Freezing in Non-Hermitian Systems

TL;DR

This paper demonstrates that in non-Hermitian quantum systems, PT-broken phases cause defect freezing during linear quenches, revealing unique nonadiabatic dynamics that require a metric framework for proper analysis.

Contribution

It introduces a consistent dynamical metric framework to analyze defect dynamics in non-Hermitian systems, uncovering defect freezing phenomena absent in Hermitian counterparts.

Findings

PT-broken modes cause defect freezing

Defect dynamics differ significantly from Hermitian systems

Metric framework is essential for accurate analysis

Abstract

Non-Hermiticity in quantum Hamiltonians leads to nonunitary time evolution and possibly complex energy eigenvalues, which can lead to a rich phenomenology with no Hermitian counterpart. In this work, we study the dynamics of an exactly solvable non-Hermitian system, hosting both $\mathcal{PT}$-symmetric and $\mathcal{PT}$-broken modes subject to a linear quench. Employing a fully consistent framework, in which the Hilbert space is endowed with a nontrivial dynamical metric, we analyze the dynamics of the generated defects. In contrast to Hermitian systems, our study reveals that PT -broken time evolution leads to defect freezing and hence the violation of adiabaticity. This physics necessitates the so-called metric framework, as it is missed by the oft used approach of normalizing quantities by the time-dependent norm of the state. Our results are relevant for a wide class of experimental systems.