Emergence of Exceptional Points in Periodic Metastructures with Hidden PT-symmetric Defects
arXiv:2207.09008 · doi:10.1115/1.4055618
Abstract
We study the elastodynamics of a periodic metastructure incorporating a defect pair that enforces a parity-time (PT) symmetry due to a judiciously engineered imaginary impedance elements - one having energy amplification (gain) and the other having an equivalent attenuation (loss) mechanism. We show that their presence affects the initial band structure of the periodic Hermitian metastructure and leads to the formation of numerous exceptional points (EPs) which are mainly located at the band edges where the local density of modes is higher. The spatial location of the PT-symmetric defect serves as an additional control over the number of emerging EPs in the corresponding spectra as well as the critical non-Hermitian (gain/loss) strength required to create the first EP - a specific defect location minimizes the critical non-Hermitian strength. We use both finite element and coupled-mode-theory-based models to investigate these metastructures, and use a time-independent second-order perturbation theory to further demonstrate the influence of the size of the metastructure and the PT-symmetric defect location on the minimum non-Hermitian strength required to create the first EP in a band. Our findings motivate feasible designs for the experimental realization of EPs in elastodynamic metastructures.
References in corpus (26)
- Real Spectra in Non-Hermitian Hamiltonians Having PT Symmetry
- Making Sense of Non-Hermitian Hamiltonians
- Unidirectional Invisibility induced by PT-Symmetric Periodic Structures
- Complex Extension of Quantum Mechanics
- PT-Symmetric Quantum Mechanics
- Dynamically encircling exceptional points in a waveguide: asymmetric mode switching from the breakdown of adiabaticity
- The emergence, coalescence and topological properties of multiple exceptional points and their experimental realization
- PT symmetry and spontaneous symmetry breaking in a microwave billiard
- PT-Symmetric Electronics
- Exponentially Fragile PT-Symmetry in Lattices with Localized Eigenmodes
- PT-Symmetry in Non-Hermitian Su-Schrieffer-Heeger model with complex boundary potentials
- Observation of Defect States in PT-Symmetric Optical Lattices
- PT-symmetric scattering in flow duct acoustics
- Non-Hermitian Acoustic Metamaterials: the role of Exceptional Points in sound absorption
- Su-Schrieffer-Heeger chain with one pair of PT-symmetric defects
- Exceptional points and enhanced sensitivity in PT-symmetric continuous elastic media
- Tunable elastic Parity-Time symmetric structure based on the shunted piezoelectric materials
- Anomalous energy transport in laminates with exceptional points
- Environmentally-induced exceptional points in elastodynamics
- Discrete solitons and scattering of lattice waves in guiding arrays with a nonlinear -symmetric defect
- PT-symmetric coupler with a coupling defect: soliton interaction with exceptional point
- Robust localized zero-energy modes from locally embedded PT-symmetric defects
- Asymmetric Acoustic Energy Transport in Non-Hermitian Metamaterials
- Scattering of gap solitons by PT-symmetric defects
- Scaling Properties of Localization Length in 1D Paired Correlated Binary Alloys of Finite Size
- Universal Route for the Emergence of Exceptional Points in PT-Symmetric Metamaterials with Unfolding Spectral Symmetries