Dynamically tuneable helicity in twisted electromagnetic resonators

Abstract

We report the generation of helical electromagnetic radiation in a microwave cavity resonator, achieved by introducing mirror asymmetry, i.e., chirality, through a controlled geometric twist of the conducting boundary conditions. The emergence of electromagnetic helicity is attributed to a nonzero spatial overlap between the electric and magnetic mode eigenvectors, quantified by $\text{Im}\left[{\vec{\mathbf{E}}}_i(\vec{r})\cdot {\vec{\mathbf{H}}}_i^{\ast }(\vec{r})\right]$, a feature not observed in conventional cavity resonators. This phenomenon originates from magnetoelectric coupling between nearly degenerate transverse electric (TE) and transverse magnetic (TM) modes, resulting in a measurable frequency shift of the resonant modes as a function of the twist angle, $\varphi$. In addition to the bulk helicity induced by global geometric twist, internal helical corrugations break structural symmetry on the surface, introducing an effective surface chirality ${\kappa }_{\text{eff}}$, which perturbs the resonant conditions and contributes to asymmetric frequency tuning. By dynamically varying $\varphi$, we demonstrate real-time, macroscopic manipulation of both electromagnetic helicity and resonant frequency. Furthermore, we investigate the underlying mode-coupling dynamics of the system, highlighting strong photon-photon interactions.

11 pages, 12 figures

References in corpus (20)

• Photonic Analogue of Two-dimensional Topological Insulators and Helical One-Way Edge Transport in Bi-Anisotropic Metamaterials
• Strongly coupled magnons and cavity microwave photons
• Dual electromagnetism: Helicity, spin, momentum, and angular momentum
• Level Attraction Due to Dissipative Magnon-Photon Coupling
• Experimental signatures of the mixed axial-gravitational anomaly in the Weyl semimetal NbP
• Chiral anomaly, Charge Density Waves, and Axion Strings from Weyl Semimetals
• Evidence for an axionic charge density wave in the Weyl semimetal (TaSe4)2I
• Tunable orbital angular momentum in high-harmonic generation
• Topological Materials Discovery from Crystal Symmetry
• Chiral anomaly from strain-induced gauge fields in Dirac and Weyl semimetals
• Magnetoelectric Effects in Local Light-Matter Interactions
• Topological non-Hermitian origin of surface Maxwell waves
• Electromagnetic helicity in complex media
• Thermal chiral anomaly in the magnetic-field induced ideal Weyl phase of Bi1-xSbx topological insulators
• Axion-Electromagnetic Waves
• Reconfigurable Microwave Photonic Topological Insulator
• Comparing Instrument Spectral Sensitivity of Dissimilar Electromagnetic Haloscopes to Axion Dark Matter and High Frequency Gravitational Waves
• Quantum routing of information using chiral quantum walks
• Searching for Ultra-Light Axions with Twisted Cavity Resonators of Anyon Rotational Symmetry with Bulk Modes of Non-Zero Helicity
• Electromagnetic Helicity in Twisted Cavity Resonators