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arXiv · 1604.06994

Spectral flow for real skew-adjoint Fredholm operators

Alan L. Carey·John Phillips·Hermann Schulz-Baldes
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Abstract

An analytic definition of a $\mathbb{Z}_2$-valued spectral flow for paths of real skew-adjoint Fredholm operators is given. It counts the parity of the number of changes in the orientation of the eigenfunctions at eigenvalue crossings through $0$ along the path. The $\mathbb{Z}_2$-valued spectral flow is shown to satisfy a concatenation property and homotopy invariance, and it provides an isomorphism on the fundamental group of the real skew-adjoint Fredholm operators. Moreover, it is connected to a $\mathbb{Z}_2$-index pairing for suitable paths. Applications concern the zero energy bound states at defects in a Majorana chain and a spectral flow interpretation for the $\mathbb{Z}_2$-polarization in these models.

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Alan L. Carey, John Phillips, Hermann Schulz-Baldes. 2016-04-24. Spectral flow for real skew-adjoint Fredholm operators. https://arxiv.org/abs/1604.06994

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