Enhanced energy harvesting near exceptional points in systems with (pseudo-)PT-symmetry

Abstract

Exceptional point degeneracies, occurring in non-Hermitian systems, have challenged many well established concepts and led to the development of remarkable technologies. Here, we propose a family of autonomous motors whose operational principle relies on exceptional points via the opportune implementation of a (pseudo-)PT-symmetry and its spontaneous or explicit violation. These motors demonstrate a parameter domain of coexisting high efficiency and maximum work. In the photonic framework, they can be propelled by thermal radiation from the ambient thermal reservoirs and utilized as autonomous self-powered microrobots, or as micro-pumps for microfluidics in biological environments. The same designs can be also implemented with electromechanical elements for harvesting ambient mechanical (e.g., vibrational) noise for powering a variety of auxiliary systems. We expect that our proposal will contribute to the research agenda of energy harvesting by introducing concepts from mathematical and non-Hermitian wave physics.

Optimising energy harvesting is relevant to a variety of micro and nanotechnologies with applications ranging from self powered nanodevices to microfluidic pumps in biological environments. Here, the authors show that an opportunely designed opto(/electro)-mechanical circuit can simultaneously demonstrate high efficiency and power production when operating in the vicinity of an exceptional point degeneracy implemented via a pseudo-PT symmetry.