Experimental realisation of $\mathcal{P}\mathcal{T}$-symmetric flat bands

Abstract

The capability to temporarily arrest the propagation of optical signals is one of the main challenges hampering the ever more widespread use of light in rapid long-distance transmission as well as all-optical on-chip signal processing or computations. To this end, flat-band structures are of particular interest, since their hallmark compact eigenstates do not only allow for the localization of wave packets, but importantly also protect their transverse profile from deterioration without the need for additional diffraction management. In this work, we experimentally demonstrate that, far from being a nuisance to be compensated, judiciously tailored loss distributions can in fact be the key ingredient in synthesizing such flat bands in non-Hermitian environments. We probe their emergence in the vicinity of an exceptional point and directly observe the associated compact localised modes that can be excited at arbitrary positions of the periodic lattice.

References in corpus (15)

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• Observation of Ground and Excited Flat Band States in Graphene Photonic Ribbons

Cited by in corpus (19)

• Exceptional Topology of Non-Hermitian Systems
• Non-Hermitian skin modes induced by on-site dissipations and chiral tunneling effect
• Quantum simulation of parity-time symmetry breaking with a superconducting quantum processor
• Fractal-like photonic lattices and localized states arising from singular and nonsingular flatbands
• Higher-order exceptional point and Landau-Zener Bloch oscillations in driven non-Hermitian photonic Lieb lattices
• Loss-difference-induced localization in a non-Hermitian honeycomb photonic lattice
• Non-Hermitian flatband generator in one dimension
• Two-dimensional weak-type topological insulators in inversion symmetric crystals
• Interplay of quantum phase transition and flat band in hybrid lattices
• Localization-Delocalization Transitions in Non-Hermitian Aharonov-Bohm Cages
• Direct observation of energy band attraction effect in non-Hermitian systems
• Multiple flat bands and localized states in photonic super-Kagome lattices
• Ultrabroadband beam splitting in a dissipative system of three waveguides
• Generalized Lieb's theorem for noninteracting non-Hermitian $n$-partite tight-binding lattices
• Surge of power transmission in flat and nearly flat band lattices
• Robust incoherent perfect absorption
• Non-diffracting states at exceptional points
• Correlated metallic two-particle bound states in Wannier--Stark flatbands
• Non-Hermitian Aharonov-Bohm Cage