Super Bloch Oscillation in a PT symmetric system

TL;DR

This paper demonstrates that non-Hermitian PT symmetric systems can support large-amplitude, non-amplified Bloch oscillations by leveraging pseudo PT symmetry to ensure real quasi-energy spectra.

Contribution

It introduces conditions under which non-amplified Bloch oscillations occur in PT symmetric lattices, highlighting the role of pseudo PT symmetry in maintaining real spectra.

Findings

Large amplitude oscillations without amplification are achievable.

Pseudo PT symmetry ensures the reality of the quasi-energy spectrum.

Conditions for non-amplified Bloch oscillations are identified.

Abstract

Wannier-Stark ladder in a PT symmetric system is generally complex that leads to amplified/damped Bloch oscillation. We show that a non-amplified wave packet oscillation with very large amplitude can be realized in a non-Hermitian tight binding lattice if certain conditions are satisfied. We show that pseudo PT symmetry guarantees the reality of the quasi energy spectrum in our system.