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Colloquium: Dr. Jorn Dunkel , Massachusetts Inst. of Tech

Wednesday, November 20, 2019
3:30 PM - 4:30 PM
Physics : 401
TITLE:  Symmetry breaking in active and quantum fluids

ABSTRACT:
 

Active biological fluids, such as bacterial and other microbial suspensions, can exhibit striking symmetry breaking phenomena, from the spontaneous formation of vortex lattices to the emergence of large-scale unidirectional flows. Borrowing ideas from classical pattern formation theory [1], I will discuss  generalized Navier-Stokes (GNS) equations [2-5] for active fluids that capture many of the experimentally observed phenomena. The GNS model permits exact stress-free bulk solutions, which include Abrikosov-type lattices in 2D [2,3] and Beltrami flows in 3D [4]. A triad analysis shows that the combination of a generic linear instability and a standard advective nonlinearity can give rise to spontaneous chiral symmetry breaking that supports inverse energy transport in 3D [4,5]. In the second part, we extend the underlying concepts to quantum fluids by deriving a higher-order generalization of the Gross-Pitaevskii model to study supersolid crystals and quasi-crystals [6].

[1] Stoop, et al. Nature Materials 14, 337 (2015)
[2] Slomka and Dunkel. Phys Rev Fluids 2, 043102 (2017)
[3] Mickelin, Slomka, et al. Phys Rev Lett 120, 164503 (2018) 
[4] Slomka and Dunkel. PNAS 114, 2119 (2017) 
[5] Slomka, Suwara and Dunkel. J Fluid Mech 841, 701 (2018)
[6] Heinonen, Burns and Dunkel. Phys Rev A 99, 063621 (2019)