Observation of scale-free localized states induced by non-Hermitian defects

Abstract

Wave localization is a fundamental phenomenon that appears universally in both natural materials and artificial structures and plays a crucial role in understanding the various physical properties of a system. Usually, a localized state has an exponential profile with a localization length independent of the system size. Here, we experimentally demonstrate a new class of localized states called scale-free localized states, which has an unfixed localization length scaling linearly with the system size. Using circuit lattices, we observe that a non-Hermitian defect added to a Hermitian lattice induces an extensive number of states with scale-free localization. Furthermore, we demonstrate that, in a lattice with a parity-time-symmetric non-Hermitian defect, the scale-free localization emerges because of spontaneous parity-time symmetry breaking. Our results uncover a new type of localized states and extend the study of defect physics to the non-Hermitian regime.

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Cited by in corpus (8)

• Erratic non-Hermitian skin localization
• Braiding Topology of Non-Hermitian Open-Boundary Bands
• Observation of Impurity-Induced Scale-Free Localization in a Disordered Non-Hermitian Electrical Circuit
• From scale-free to Anderson localization: a size-dependent transition
• Scale-free localization versus Anderson localization in unidirectional quasiperiodic lattices
• Quantum Sensing with Driven-Dissipative Su-Schrieffer-Heeger Lattices
• Orthogonality catastrophe beyond bosonization from post-selection
• Concurrent Skin-scale-free Localization and Criticality under Möbius Boundary Conditions in a Non-Hermitian Ladder