Exceptional Cones in 4D Parameter Space

Abstract

The notion of synthetic dimensions has expanded the realm of topological physics to four dimensional (4D) space lately. In this work, non-Hermiticity is used as a synthetic parameter in PT-symmetric photonic crystals to study the topological physics in 4D non-Hermitian synthetic parameter space. We realize a 3D exceptional hypersurface (EHS) in such 4D parameter space, and the degeneracy points emerge due to the symmetry of synthetic parameters. We further demonstrate the existence of exceptional degenerate points (EDPs) on the EHS that originates from the chirality of exceptional points (EPs), and the exceptional surface near EDPs behaves like a Dirac cone. We further show that a very narrow reflection plateau can be found near these EDPs, and their sensitivity towards the PT-symmetry breaking environmental perturbation can make these degeneracy points useful in optical sensing and many other nonlinear and quantum optical applications.

References in corpus (11)

• Chiral tunneling and the Klein paradox in graphene
• Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
• Photonic topological pumping through the edges of a dynamical four-dimensional quantum Hall system
• Weyl Exceptional Rings in a Three-Dimensional Dissipative Cold Atomic Gas
• Reversing the Pump-Dependence of a Laser at an Exceptional Point
• Exploring 4D Quantum Hall Physics with a 2D Topological Charge Pump
• Topological quantum matter in synthetic dimensions
• Light stops at exceptional points
• Probing Weyl Physics with One-dimensional Sonic Crystals
• Chern-Simons Theory and Wilson Loops in the Brillouin Zone
• Non-Hermitian heterostructure for two-parameter sensing