Synthetic high-order PT symmetry in a single coil resonator

TL;DR

This paper demonstrates a novel synthetic high-order PT symmetry in a single coil resonator using internal bypass capacitors, enabling higher-order exceptional points without multiple spatially separated coils, thus advancing non-Hermitian physics research.

Contribution

It introduces a new method to realize second- and third-order PT symmetry in a single coil resonator through internal coupling, eliminating the need for multiple coils in spatial PT systems.

Findings

Observation of second-order PT phase transition in a single coil.

Realization of synthetic high-order PT symmetry with internal components.

Potential extension to optics and acoustics platforms.

Abstract

The exploration of non-Hermitian systems with parity-time (PT) symmetry has witnessed immense research interest both fundamentally and technologically in a wide range of subject areas in physics and engineering. One significant example of the principal emerging fields in this context is the PT symmetric wireless applications using multiple coils that are spatially separated but mutually coupled with position-dependent coupling strength. Such a spatial PT configuration limits the flexibility and miniaturization of the PT symmetric designs. As far as this is concerned, inspired by scattering induced two opposite whispering-gallery (WG) modes in an optical resonator, analogously here we experimentally demonstrate a specially constructed second-order (2-nd order) PT symmetry in a single coil resonator, whose currents with two different directions are excited by internal bypass capacitor. Our proposed structure has the following peculiar feature: First, the bypass capacitor induces coupling in spectral resonances allow us to observe a 2-nd order phase transition between symmetry regimes, without the need of a second coil in the spatial PT case. Under this circumstance, this specially constructed PT symmetry can be regarded as synthetic PT symmetry, which is enabled by coupling modes with different directions. Second, by introducing two or more internal bypass capacitors, the synthetic high-order PT symmetric system bearing such as third-order exceptional point in a single coil resonator can be realized. These results will provide a new paradigm to realize higher-order PT symmetry towards the investigation of non-Hermitian physics in a synthetic perspective, which can be extended to other physical platforms such as optics and acoustics.