Constant intensity discrete diffraction in anti-PT-symmetric electric circuits

Abstract

We theoretically investigate the time-domain dynamics in a non-Hermitian electric circuit network with anti-parity-time (anti-PT) symmetry, which is consisted of amplified resonant LRC circuits connected by resistors. The effective coupling strength and on-site potential can be flexibly tuned via controlling the resistance value and resonant frequencies of LRC circuits, respectively. Therein, we are able to realize all three symmetry phases of the system, including anti-PT symmetric, intermediate, and broken phases, which are distinguished from their band structures. We show the time evolution of the envelope of voltage is analogous to discrete diffraction as a single injection stimulates more and more channels over time. Specifically, the system exhibits constant intensity diffraction at the boundary between intermediate and broken phases as the voltages at different channels are of the same value during the evolution. The reason lies in the dispersionless band structure near exceptional points (EPs) and the related linear energy amplification. The results enrich the study of discrete diffraction and are helpful to further exploration of topological phenomena in anti-PT-symmetric systems.