Observation of Novel Robust Edge States in Dissipative Non-Hermitian Quantum Walks

Recently, the study of non-Hermitian physics has attracted considerable attention. The modified bulk-boundary correspondence has been proposed to understand topological edge states in non-Hermitian static systems. Here, a new experimental observation of edge states in non-Hermitian time-driven systems (quantum walks) is reported. Topologically edge states protected by Hermitian conjugation of particle-hole symmetry (PHS dagger) are found in the unbroken parity-time (PT)-symmetric phase. When the system changes from the unbroken to the broken PT-symmetric phase, the topological phase transition occurs accompanied by the change of the number of edge states. The robust properties of these edge states against static perturbations and disorder are also demonstrated experimentally. The finding of robust edge states in non-Hermitian systems inspires to explore a robust transport channel in ubiquitously complex systems with strong dissipation.