“…EPs are at the heart of many intriguing physical phenomena appearing in several systems that experience gain or loss. They have been predicted and observed in a wide variety of physical systems, including atomic and molecular systems [13,14,15], microwave cavities and waveguides [16,17,18], electronic circuits [19], optical structures [20,21], Bose-Einstein condensates [22,23], acoustic cavities [24], non-Hermitian Bose-Hubbard models [25], exciton-polariton billiards [26], opto-mechanical systems [27] and many others. Besides of their theoretical interest, EPs can find important applications, for example in the design and realization of unidirectionally invisible media [28,29,30,31,32], for asymmetric mode switching [18,33] and topological energy transport [27], for the design of novel laser devices [34,35,36,37,38], for optical sensing [39] and polarization mode conversion [40].…”