Energy Band Attraction Effect in Non-Hermitian Systems

Area of Science:

• Photonics
• Metamaterials
• Quantum Physics

Background:

• Non-Hermitian (NH) systems exhibit unique phenomena like energy band attraction (EBA) due to nonorthogonal eigenvectors.
• Experimental demonstration of EBA has been limited by the need for tight-binding approximations and complex potentials.

Purpose of the Study:

• To experimentally verify the photonic analog of EBA in a designed all-dielectric Mie resonator system.
• To investigate the evolution of EBA in a two-level NH system by tuning resonator loss.
• To extend the demonstrated methods to a two-dimensional NH system.

Main Methods:

• Utilized all-dielectric Mie resonators in a parallel-plate transmission line to create a photonic NH system.
• Theoretically and experimentally analyzed the transmission spectra, eigenvalues, and eigenvectors.
• Precisely tuned the loss of Mie resonators to observe band evolution.

Main Results:

• First experimental verification of the photonic analog of EBA.
• Observed the transition of EBA from gapped to gapless to flat bands by controlling resonator loss.
• Established a connection between transmission spectra and NH Hamiltonian eigenvalues/eigenvectors.
• Extended the approach to a graphenelike 2D NH system.

Conclusions:

• Metamaterial approach provides a viable route for realizing NH topological photonics.
• The study deepens the understanding of band theory in open quantum systems.
• This work paves the way for future experimental investigations of NH phenomena in photonics.