Exceptional Points of Degeneracy Induced by Time-Periodic Modulation

An exceptional point of degeneracy (EPD) is a point in parameter space where at least two eigenvalues and eigenvectors of a system coalesce. We explore the occurrence of EPD in electronic, electromagnetic and mechanical time-varying systems. Remarkably, when using time variation of a system component, EPDs exist in a single resonator and they can be found by just tuning the modulation frequency. We demonstrate EPDs of the second order in linear-time-periodic (LTP) systems and offer examples of their applications, such as sensing and power harvesting.