Advances in Optical and Microwave Nonreciprocity

TL;DR

This paper reviews recent advances in optical and microwave nonreciprocity, highlighting new materials, active structures, and quantum effects that enable non-magnetic reciprocity breaking for photonic and quantum technologies.

Contribution

It provides a comprehensive overview of emerging methods and materials for achieving nonreciprocity beyond traditional magnet-based devices.

Findings

New materials like Weyl semimetals and topological insulators enable nonreciprocity.

Active and time-modulated structures offer alternative nonreciprocal functionalities.

Quantum effects and chiral states contribute to advanced nonreciprocal device concepts.

Abstract

Modern photonic and quantum technologies demand reciprocity breaking, e.g., isolators, full-duplex systems, noise isolation in quantum computers, motivating searching for practical approaches beyond magnet-based devices. This work overviews the up-and-coming advances in optical nonreciprocity, including new materials (Weyl semimetals, topological insulators, metasurfaces), active structures, time-modulation, PT-symmetry breaking, nonlinearity, quantum nonlinearity, unidirectional gain and loss, chiral quantum states, and valley polarization.