Reconfigurable enhancement of actuation forces by engineered losses in non-Hermitian metamaterials

Dear Colleagues, 

I invite you to read our recent Extreme Mechanics Letters paper presenting a novel viewpoint on enhancing emissivity near exceptional point singularities in a non-Hermitian metamaterial. We present the experiments and numerical modeling in an elastodynamic framework--where the actuation forces from an actuator are enhanced by coupling to a passive dissipative non-Hermitian metamaterial--and present the theory further generalized and applicable to other physical frameworks from acoustics to optics and microwaves.

Abstract

While boosting signals with amplification mechanisms is a well-established approach, attenuation mechanisms are typically considered an anathema because they degrade the efficiency of the structures employed to perform useful operations on these signals. An emerging alternate viewpoint promotes losses as a novel design element by utilizing the notion of exceptional point degeneracies (EPDs)—points in parameter space where the eigenvalues of the underlying system and the associated eigenvectors simultaneously coalesce. Here, we demonstrate a direct consequence of such eigenbasis collapse in elastodynamics—an unusual enhancement of actuation force by a judiciously designed non-Hermitian metamaterial supporting an EPD that is coupled to an actuation source. Intriguingly, the EPD enables this enhancement while maintaining a constant signal quality. Our work constitutes a proof-of-principle design which can promote a new class of reconfigurable nano-indenters and robotic-actuators. Importantly, it reveals the ramifications of non-Hermiticity in boosting the Purcell emissivity enhancement factor beyond its expected value, which can guide the design of metamaterials with enhanced emission that does not deteriorate signal quality for mechanical, acoustic, optical, and photonic applications.

Read the full article here: https://doi.org/10.1016/j.eml.2023.101979