Dirac Points Embedded in the Continuum
arXiv:2212.05864 · doi:10.1103/PhysRevB.108.205106
Abstract
Dirac points (DP) in Hermitian systems play a key role in topological phenomena. Their existence in non-Hermitian systems is then desirable, but the addition of loss or gain transforms DPs into pairs of Exceptional Points (EPs) joined by a Fermi arc, which exhibit interesting but different properties. When the transition to a non-Hermitian system results from the opening of a radiation channel, the system can also support bound states in the continuum (BICs), which are non-radiative resonant states that appear within the band of radiation states. We theoretically show that simultaneous band-crossing of two BICs can prevent the formation of EPs and Fermi arcs, resulting in genuine Hermitian DPs, which are nonetheless embedded in the continuum of radiation states. Dirac points embedded in the continuum (DECs) are a new topological entity that combines the rich physics associated with DPs with the ideal resonant properties of BICs in non-Hermitian systems.
References in corpus (25)
- The electronic properties of graphene
- Quantum Spin Hall Effect in Graphene
- Topological Photonics
- Possible Realization of Directional Optical Waveguides in Photonic Crystals with Broken Time-Reversal Symmetry
- Edge states and topological invariants of non-Hermitian systems
- Non-Hermitian Physics
- Beyond Dirac and Weyl fermions: Unconventional quasiparticles in conventional crystals
- Topological Band Theory for Non-Hermitian Hamiltonians
- Electromagnetic Wave Propagation in Media with Indefinite Permittivity and Permeability Tensors
- Dynamically encircling exceptional points in a waveguide: asymmetric mode switching from the breakdown of adiabaticity
- Spawning rings of exceptional points out of Dirac cones
- Edge Modes, Degeneracies, and Topological Numbers in Non-Hermitian Systems
- Topologically Enabled Ultra-high-Q Guided Resonances Robust to Out-of-plane Scattering
- Observation of Bulk Fermi Arc and Polarization Half Charge from Paired Exceptional Points
- Anisotropy-induced photonic bound states in the continuum
- Bulk photonic metamaterial with hyperbolic dispersion
- Zero-index bound states in the continuum
- Non-Hermitian Dirac Cones
- Bound states in the continuum through environmental design
- Low-loss Zero-Index Materials
- Topological properties of bound-states-in-the-continuum in geometries with broken anisotropy-symmetry
- Angular Control of Anisotropy-Induced Bound States in the Continuum
- Bound states in the continuum and exceptional points in dielectric waveguide equipped with a metal grating
- Transition from Dirac points to exceptional points in anisotropic waveguides
- Surface Bound States in the Continuum in Dyakonov Structures