EFRI NewLAW: Non-Reciprocal Wave Propagation Devices by Fermionic Emulation and Exceptional Point Physics

Cornell University, Ithaca NY

Investigators

Abstract

No device exists today that efficiently allows light to move forward in one direction, but stops it from moving in reverse. Devices that serve as one-way lanes for light propagation can revolutionize communication system design by adding new functionalities in a compact and more energy-efficient way. Similarly, electronics can be made more energy-efficient by suppressing back scattering. New discoveries in the past decade in the physics of wave propagation in materials have given tantalizing hints as to how one may achieve one-way devices for light and electron waves. Taking these hints towards practical engineering devices, however, requires theoretical design and experimental advances in materials and device fabrication. By bringing together a diverse and multidisciplinary team with the necessary skills, this project aims to develop the fundamental science behind such advances and experimentally demonstrate one-way devices for future information systems. This NewLAW EFRI team will investigate topological, chiral, and non-reciprocal transport of photons, polaritons, plasmons, and electron waves. This will be achieved by using specially designed material systems and device structures that provide non-trivial topological properties for electrons, for photons, and for light-matter hybrids such as non-trivial manifestations of collective plasmons and trion-polaritons. By engineering the interactions between electrons and photons in non-trivial ways, new science and new engineering technologies will be explored. Instead of photons or excitons, trions that are fermions with net charge and spin will be investigated for non-reciprocal light transport in the form of trion-polaritons. Instead of plasmons, chiral plasmons will be used for non-reciprocal transport. As a demonstration of non-reciprocal light transport, a novel optical isolator will be realized that demonstrates simultaneously high linearity, high bandwidth and high dynamic range - characteristics lacking in previous embodiments. The rich physics of non-Hermitian systems will be used to realize novel topologically-enhanced non-reciprocal waveguides. Similar non-Hermitian physics effects in the context of electron waves will be explored for electronic non-reciprocity. In this case, propagation in the evanescent complex momentum domain via electron tunneling will be explored in a device platform in specially designed material heterostructure. The EFRI team will combine theoretical research, with synthesis of new materials, and fabrication of non-reciprocal devices to achieve the above goals. Because the lack of efficient non-reciprocal wave propagation devices currently limits several functionalities in communication systems, the results of this team's research are expected to uncover new physics and engineering possibilities, contributing towards the development of communication systems that significantly affect the movement of information. The realization of the proposed devices requires a unifying theme guided by theoretical design to provide mathematical and physical understanding and guidance, experimental realization of specially designed materials such as 2D crystal heterostructures and III-Nitride semiconductors, nanofabrication of the device structures that assemble these materials in specified geometries, and finally, testing and measurement of the predicted non-reciprocal wave transport. The overarching goals are to advance the understanding of fundamental principles of non-reciprocity in novel electronic and photonic media, and to exploit these principles to realize non-reciprocal devices with superior performance. The EFRI team brings together five investigators with the precise set of skills necessary to achieve these goals.