Direct observation of time-asymmetric breakdown of the standard adiabaticity around an exceptional point

• Published in: Communications physics 2020-08, Vol.3 (1), Article 140
• Main Authors: Choi, Youngsun, Yoon, Jae Woong, Hong, Jong Kyun, Ryu, Yeonghwa, Song, Seok Ho
• Format: Article
• Language: English
• Subjects: 639/766/1130/2798; 639/766/483/3926; Adiabatic flow; Asymmetry; Breakdown; Eigenvalues; Evolution; Oscillators; Physics; Physics and Astronomy; Singularities; Topology
• ISSN: 2399-3650; 2399-3650
• DOI: 10.1038/s42005-020-00409-y

Recent study on topological operations around an exceptional point singularity has shown remarkably robust chiral processes that potentially create time-asymmetric or nonreciprocal systems and devices. Nevertheless, direct observation of the entire dynamics in the courses of the topological operations has not been revealed in experiments thus far. Here, we report a comprehensive experimental study on fully time-resolved dynamic-state evolution passages during encircling-an-exceptional-point operations. Using dynamically tunable electrical oscillators, we create a self-intersecting eigenvalue topology with an unprecedented accuracy and experimentally confirm that the time-asymmetric breakdown of the standard adiabaticity is indeed unavoidable when the system encircles an exceptional point in the canonical adiabatic limit. We further discuss the impact of parasitic noises on the time-asymmetric mode-transfer performance and subsequent considerations for practical design requirements. So far, chiral topological operations around an exceptional point singularity were experimentally observable through the system’s initial and final states only. Here, the authors propose an experimental set up that allows them to access the full time-resolved evolution during encircling-an-exceptional-point operations.