Topological sound and flocking on curved surfaces

Suraj Shankar, Mark John Bowick, M Cristina Marchetti

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Active systems on curved geometries are ubiquitous in the living world. In the presence of curvature, orientationally ordered polar flocks are forced to be inhomogeneous, often requiring the presence of topological defects even in the steady state because of the constraints imposed by the topology of the underlying surface. In the presence of spontaneous flow, the system additionally supports long-wavelength propagating sound modes that get gapped by the curvature of the underlying substrate. We analytically compute the steady-state profile of an active polar flock on a two-sphere and a catenoid, and show that curvature and active flow together result in symmetry-protected topological modes that get localized to special geodesics on the surface (the equator or the neck, respectively). These modes are the analogue of edge states in electronic quantum Hall systems and provide unidirectional channels for information transport in the flock, robust against disorder and backscattering.

Original languageEnglish (US)
Article number031039
JournalPhysical Review X
Volume7
Issue number3
DOIs
StatePublished - Sep 7 2017

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curved surfaces
curvature
acoustics
quantum electronics
support systems
equators
backscattering
topology
disorders
analogs
defects
symmetry
profiles
geometry
wavelengths

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Shankar, S., Bowick, M. J., & Marchetti, M. C. (2017). Topological sound and flocking on curved surfaces. Physical Review X, 7(3), [031039]. https://doi.org/10.1103/PhysRevX.7.031039

Topological sound and flocking on curved surfaces. / Shankar, Suraj; Bowick, Mark John; Marchetti, M Cristina.

In: Physical Review X, Vol. 7, No. 3, 031039, 07.09.2017.

Research output: Contribution to journalArticle

Shankar, S, Bowick, MJ & Marchetti, MC 2017, 'Topological sound and flocking on curved surfaces', Physical Review X, vol. 7, no. 3, 031039. https://doi.org/10.1103/PhysRevX.7.031039
Shankar, Suraj ; Bowick, Mark John ; Marchetti, M Cristina. / Topological sound and flocking on curved surfaces. In: Physical Review X. 2017 ; Vol. 7, No. 3.
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