Floquet exceptional points and chirality in non-Hermitian Hamiltonians

TL;DR

This paper explores the emergence of Floquet exceptional points in non-Hermitian Hamiltonians and their connection to chiral dynamics during slow parameter cycling, revealing new insights into non-Hermitian Floquet systems.

Contribution

It introduces the concept of Floquet exceptional points in time-periodic non-Hermitian systems and analyzes their role in chiral behavior over multiple oscillation cycles.

Findings

Floquet exceptional points occur at multiphoton resonance conditions.

Chiral dynamics manifest over several cycles when parameters are cycled slowly.

The study links Floquet exceptional points to observable chiral effects in non-Hermitian systems.

Abstract

Floquet exceptional points correspond to the coalescence of two (or more) quasi-energies and corresponding Floquet eigenstates of a time-periodic non-Hermitian Hamiltonian. They generally arise when the oscillation frequency satisfies a multiphoton resonance condition. Here we discuss the interplay between Floquet exceptional points and the chiral dynamics observed, over several oscillation cycles, in a wide class of non-Hermitian systems when they are slowly cycled in opposite directions of parameter space.