Recently, Associate Researcher Dengke Qu from Southeast University’s All-Optical Quantum Information Team made an important breakthrough in the field of non-Hermitian photonics, achieving the first experimental realization of programmable chiral multistate switching. The related work, titled “Selective Chiral Multistate Switching via the Dynamic Interplay of Diabolic and Exceptional Points,” was published in the internationally renowned physics journal Physical Review Letters.
Non-Hermitian systems exhibit a wealth of physical phenomena due to the presence of exceptional points in their energy spectra. In particular, dynamically encircling an exceptional point can induce chiral state transfer, where the system’s final state is determined solely by the encircling direction, regardless of the initial state. Previously, this phenomenon had been largely limited to two-mode systems. In higher-dimensional multimode systems, however, the combined effects of multiple exceptional points and nonadiabatic transitions have made precise control of the final state a major challenge in the field.
To address this problem, the research team constructed a four-mode coupled non-Hermitian system model and effectively simulated its time-dependent dynamics on a single-photon interferometric platform. By precisely designing the evolution path of the system parameters so that the path simultaneously encircled the exceptional curve and crossed the diabolic curve in parameter space, they achieved fully programmable switching among four eigenstates. Experimental results showed that, by selecting different evolution paths and encircling directions, the system could be deterministically transferred from any initial state to any desired target state.
Figure 1. Schematic of the four-mode non-Hermitian system structure and the experimental setup.
This work breaks through the traditional limitation of non-Hermitian chiral state transfer to two-mode systems and represents the first experimental realization of a programmable multistate switching mechanism in a multimode system. The study not only deepens understanding of the spectral topological structure of non-Hermitian multimode systems, but also provides a new technical route for state manipulation in multimode photonic networks and for high-dimensional quantum information processing.
The paper’s co-first authors are Associate Researcher Dengke Qu of Southeast University, Assistant Professor Ievgen I. Arkhipov of Palacký University in the Czech Republic, and Postdoctoral Researcher Huixia Gao of Southeast University. The theoretical collaborator is Professor Franco Nori of RIKEN, Japan. The School of Physics at Southeast University is the primary affiliated institution of the work. This research was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, and the Open Project of the Beijing National Laboratory for Condensed Matter Physics.
Link:https://journals.aps.org/prl/abstract/10.1103/wvrz-432c
