title: Topologically robust sound propagation in an angular-momentum-biased graphene-like resonator lattice.
abstract: Topological insulators do not allow conduction in the bulk, yet they support edge modes that travel along the boundary only in one direction, determined by the carried electron spin, with inherent robustness to defects and disorder. Topological insulators have inspired analogues in photonics and optics, in which one-way edge propagation in topologically protected two-dimensional materials is achieved breaking time-reversal symmetry with a magnetic bias. Here, we introduce the concept of topological order in classical acoustics, realizing robust topological protection and one-way edge propagation of sound in a suitably designed resonator lattice biased with angular momentum, forming the acoustic analogue of a magnetically biased graphene layer. Extending the concept of an acoustic nonreciprocal circulator based on angular-momentum bias, time-reversal symmetry is broken here using moderate rotational motion of air within each element of the lattice, which takes the role of the electron spin in determining the direction of modal edge propagation.
authors.affiliation: Department of Physics, Queens College of The City University of New York, Queens, New York 11367, USA.|Department of Physics, The Graduate Center of The City University of New York, New York, New York 10016, USA.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Khanikaev
authors.affiliation: The Department of Electrical and Computer Engineering, The University of Texas at Austin, 1616 Guadalupe Street, UTA 7.215, Austin, Texas 78701, USA.
authors.forename: Romain
authors.initials: R
authors.lastname: Fleury
authors.affiliation: The Department of Electrical and Computer Engineering, The University of Texas at Austin, 1616 Guadalupe Street, UTA 7.215, Austin, Texas 78701, USA.
authors.forename: S Hossein
authors.initials: SH
authors.lastname: Mousavi
authors.affiliation: The Department of Electrical and Computer Engineering, The University of Texas at Austin, 1616 Guadalupe Street, UTA 7.215, Austin, Texas 78701, USA.
authors.forename: Andrea
authors.identifier: http://orcid.org/0000-0002-4297-5274
authors.initials: A
authors.lastname: Alù