Topological waves and odd viscosity in chiral active fluids

Dr Anton Souslov runs the Theoretical Physics lab at the University of Bath. He is coming to Leeds to present some of his research to the Soft Matter Physics Group.

Out-of-equilibrium fluids with active-rotor constituents have been experimentally realised using nanoscale biomolecular motors, microscale active colloids, or macroscale driven chiral grains. I will discuss how such chiral active fluids break both parity and time-reversal symmetries in their steady states, giving rise to dissipationless linear-response coefficients in the viscosity tensor, collectively called odd (equivalently, Hall) viscosity. I will explore how odd viscosity leads to topological protection of sound waves at the edge of the fluid and along fluid-fluid interfaces. As the sign of odd viscosity changes, a topological phase transition occurs without closing the bulk band gap.

References:

[1] A. Souslov, K. Dasbiswas, M. Fruchart, S. Vaikuntanathan, and V. Vitelli. Topological Waves in Fluids with Odd Viscosity. Phys. Rev. Lett. 122, 128001 (2019).

[2] D. Banerjee*, A. Souslov*, A. G. Abanov, V. Vitelli. Odd viscosity in chiral active fluids. Nat. Commun. 8, 1573 (2017).

Host: Dr Mamatha Nagaraj