Non-Hermitian Bloch-Zener phase transition

TL;DR

This paper investigates a phase transition in non-Hermitian lattices where Bloch-Zener oscillations change from aperiodic to periodic, revealing unique smooth or sharp transition behaviors, with a proposed experimental setup using photonic quantum walks.

Contribution

It introduces the concept of a non-Hermitian Bloch-Zener phase transition and suggests an experimental realization using photonic quantum walks.

Findings

BZO can transition from aperiodic to periodic in NH lattices.

The phase transition can be smooth or sharp, unlike other NH transitions.

Experimental observation is feasible with photonic quantum walks.

Abstract

Bloch-Zener oscillations (BZO), i.e. the interplay between Bloch oscillations and Zener tunneling in two-band lattices under an external dc force, are ubiquitous in different areas of wave physics, including photonics. While in Hermitian systems such oscillations are rather generally aperiodic and only accidentally periodic, in non-Hermitian (NH) lattices BZO can show a transition from aperiodic to periodic as a NH parameter in the system is varied. Remarkably, the phase transition can be either smooth or sharp, contrary to other types of NH phase transitions which are universally sharp. A discrete-time photonic quantum walk on a synthetic lattice is suggested for an experimental observation of smooth BZO phase transitions.