Winding Number Statistics of a Parametric Chiral Symplectic Random Matrix Ensemble

Abstract

The winding number is a simple topological invariant. In the case of chiral symmetry it characterises gapped phases of Fermions. We study statistical properties of this topological index or invariant in a chiral symplectic setting using Random Matrix Theory. We consider ensembles of Hamilton matrices in the symmetry class CII (quaternionic matrices) according to the classification in the tenfold way. We set up a parametric random matrix model and derive expressions for parametric correlations of the winding number density as well as for the discrete winding number distribution. We found a super-universality in the limit of large matrix dimensions for the one- and two-point correlators for the bulk of parameters, meaning that the results agree up to rescaling with those of the class AIII (complex matrices). In this context we employ a new method of unfolding and discover the Gaussian behaviour of the winding number distribution.