Exponentially growing bulk Green functions as signature of nontrivial non-Hermitian winding number in one dimension

  title={Exponentially growing bulk Green functions as signature of nontrivial non-Hermitian winding number in one dimension},
  author={Heinrich-Gregor Zirnstein and Bernd Rosenow},
  journal={arXiv: Mesoscale and Nanoscale Physics},
A nonzero non-Hermitian winding number indicates that a gapped system is in a nontrivial topological class due to the non-Hermiticity of its Hamiltonian. While for Hermitian systems nontrivial topological quantum numbers are reflected by the existence of edge states, a nonzero non-Hermitian winding number impacts a system's bulk response. To establish this relation, we introduce the bulk Green function, which describes the response of a gapped system to an external perturbation on timescales… 

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