Non-renormalization of the Hall viscosity of integer and Jain fractional quantum Hall phases by Coulomb interactions

TL;DR

This paper proves that Coulomb interactions do not alter the Hall viscosity in integer and fractional quantum Hall states, using topological invariants and composite fermion theory.

Contribution

It provides a topological proof of the non-renormalization of Hall viscosity by Coulomb interactions in quantum Hall phases.

Findings

Hall viscosity remains unchanged under Coulomb interactions.

Derived a topological expression for Hall viscosity in quantum Hall states.

Identified the role of composite fermion orbital spin in Hall viscosity.

Abstract

We proof the non-renormalization of the Hall viscosity by Coulomb interactions for integer and fractional quantum Hall Jain states building on previous results obtained for the Hall conductivity. We employ Wigner-Weyl calculus in order to represent the Hall viscosity in terms of a topological invariant comprised of Green functions and work within the composite fermion field theory model of Jain states of the fractional quantum Hall fluid presented by Lopez and Fradkin. The topological expression is first derived within the free field theory of electrons and explicitly calculated for this case as well as in the mean field approximation of the composite fermion theory Jain states. The topological orbital spin of composite fermions distinguishes their mean field treatment from that of electrons resulting in an additional topological contribution. We then argue that the introduction of Coulomb interactions does not lead to perturbative corrections of the Hall viscosity in both integer and fractional quantum Hall fluids. The proof relies on the assumptions of homogeneity and rotational invariance of an underlying sample modulo the vector potential giving rise to the homogeneous external magnetic field. These conditions imply a Hall viscosity per emergent quasiparticle number density quantized in units of one half times the average quasiparticle orbital spin or one quarter times the Wen-Zee shift. The latter features a contribution from the composite fermion topological orbital spin relative to that of electrons.