Non-Hermitian Dirac Cones

TL;DR

This paper introduces non-Hermitian lattice models that stabilize Dirac points using symmetry, enabling control over topological phenomena like phase transitions and surface states through gain and loss.

Contribution

It presents a novel class of non-Hermitian models with symmetry-stabilized Dirac points, expanding the understanding of topological phases in non-Hermitian systems.

Findings

Existence of symmetry-stabilized Dirac points in non-Hermitian lattices

Observation of topological phase transitions induced by non-Hermiticity

Control of surface states and Landau levels via gain and loss

Abstract

Non-Hermitian systems, which contain gain or loss, commonly host exceptional point degeneracies rather than the diabolic points found in Hermitian systems. We present a class of non-Hermitian lattice models with symmetry-stabilized diabolic points, such as Dirac or Weyl points. They exhibit non-Hermiticity-induced phenomena previously existing in the Hermitian regime, including topological phase transitions, Landau levels induced by pseudo-magnetic fields, and Fermi arc surface states. These behaviors are controllable via gain and loss, with promising applications in tunable active topological devices.