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SUMMARY:Hall Viscosity in Quantum Systems with Discrete Symmetry - Barry B
 radlyn\, University of Illinois at Urbana-Champaign
DTSTART:20200625T150000Z
DTEND:20200625T160000Z
UID:TALK149764@talks.cam.ac.uk
CONTACT:Jan Behrends
DESCRIPTION:From the stagnant flow of honey to the drag forces on a ball i
 n air\, nature provides many examples of viscosity\, which dissipates powe
 r and slows things down. In some exotic classical and quantum fluids\, the
 re are also "Hall" viscosities\, components of viscosity that do not dissi
 pate power\, instead providing forces transverse to fluid motion. However\
 , the standard approach to hydrodynamics assumes rotational symmetry\, whi
 ch is absent in many electron fluids. In this talk\, we examine the non-di
 ssipative Hall viscosity in systems with both discrete symmetry (translati
 onal & rotational) and internal degrees of freedom. We first examine the r
 otational symmetry breaking components of the Hall viscosity in systems wi
 th point group symmetry\, with a focus on the hydrodynamic implications of
  the resulting forces. We find that though there are generally six Hall vi
 scosities\, there are only three independent contributions to the viscous 
 force density.  To compute these coefficients\, we develop a framework to 
 consistently define the long-wavelength stress and viscosity tensors for m
 ulti-component lattice and continuum systems\, emphasizing the importance 
 of internal angular momentum. We conclude by applying our formalism to sev
 eral example topological systems both on the lattice and in the continuum.
LOCATION:Details of video conferencing will be distributed nearer the time
 .
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