Experimental Demonstration of Exceptional Points of Degeneracy in Linear Time Periodic Systems and Exceptional Sensitivity

TL;DR

This paper experimentally demonstrates exceptional points of degeneracy in a single time-periodic resonator, revealing their potential for creating highly sensitive sensors by exploiting eigenstate coalescence.

Contribution

It introduces a novel method to achieve EPDs in a single resonator through time modulation, eliminating the need for coupled resonators with gain and loss.

Findings

EPDs observed in a single time-varying resonator

System sensitivity dramatically increased at EPDs

Potential for highly sensitive sensors using time modulation

Abstract

We present the experimental demonstration of the occurrence of exceptional points of degeneracy (EPDs) in a single resonator by introducing a linear time-periodic variation of one of its components, in contrast to EPDs in parity time (PT)-symmetric systems that require two coupled resonators with precise values of gain and loss. In the proposed scheme, only the tuning of the modulation frequency is required that is easily achieved in electronic systems. The EPD is a point in a system parameters' space at which two or more eigenstates coalesce, and this leads to unique properties not occurring at other non-degenerate operating points. We show theoretically and experimentally the existence of a second order EPD in a time-varying single resonator. Furthermore, we measure the sensitivity of the proposed system to a small structural perturbation and show that the operation of the system at an EPD dramatically boosts its sensitivity performance to very small perturbations. Also, we show experimentally how this unique sensitivity induced by an EPD can be used to devise new exceptionally-sensitive sensors based on a single resonator by simply applying time modulation.