Observation of pi/2 modes in an acoustic Floquet system

Abstract

Topological phases of matter have remained an active area of research in the last few decades. Periodic driving is known to be a powerful tool for enriching such exotic phases, which leads to various phenomena with no static analogs. One such phenomenon is the emergence of the elusive $pi/2$ modes, i.e., a type of topological boundary state pinned at a quarter of the driving frequency. The latter may lead to the formation of Floquet parafermions in the presence of interaction, which is known to support more computational power than Majorana particles. In this work, we experimentally verify the signature of $\pi /2$ modes in an acoustic waveguide array, which is designed to simulate a square-root periodically driven Su-Schrieffer-Heeger model. This is accomplished by confirming the $4T$-periodicity ($T$ being the driving period) profile of an initial-boundary excitation, which we also show theoretically to be the smoking gun evidence of $\pi /2$ modes. Our findings are expected to motivate further studies of $\pi /2$ modes in quantum systems for potential technological applications.

6 pages, 3 figure. Comments are welcome

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Cited by in corpus (26)

• Non-Hermitian Floquet Topological Matter -- A Review
• Observation of $\pi$ solitons in oscillating waveguide arrays
• Generalized bulk-boundary correspondence in periodically driven non-Hermitian systems
• Kaleidoscopes of Hofstadter Butterflies and Aharonov-Bohm caging from $2^n$-root topology in decorated square lattices
• Floquet edge solitons in modulated trimer waveguide arrays
• Anomalous topological edge modes in a periodically-driven trimer lattice
• Dynamical Detection of Topological Spectral Density
• Topological Phases of Tight-Binding Trimer Lattice in the BDI Symmetry Class
• The Streda Formula for Floquet Systems: Topological Invariants and Quantized Anomalies from Cesaro Summation
• Topological $n$-root Su-Schrieffer-Heeger model in a non-Hermitian photonic ring system
• Anomalous Floquet Phases. A resonance phenomena
• $\pi$-solitons on a ring of waveguides
• Symmetry-driven Phononic Metamaterials
• Floquet non-Abelian topological charges and edge states
• Quantum geometry and geometric entanglement entropy of one-dimensional Floquet topological matter
• Generalized Majorana edge modes in a number-conserving periodically driven $p$-wave superconductor
• Floquet Möbius topological insulators
• Breakdown of boundary criticality and exotic topological semimetals in $\mathcal{P}\mathcal{T}$-invariant systems
• Floquet composite Dirac semimetals
• Network model for magnetic higher-order topological phases
• High-root topological edge-state bands
• Semimetals without correspondence between the topological charge of nodal line/surface and Fermi arc
• Breakdown of the symmetry constraint in a Floquet topological insulator
• Zero and Nonzero Energy Majorana Modes in an Extended Kitaev Chain
• Topology and edge modes surviving criticality in non-Hermitian Floquet systems
• Exceptional horns in $n$-root graphene and Lieb photonic ring lattices