Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 85: Topological Insulators III (joined session with TT)

HL 85.7: Talk

Friday, March 24, 2017, 11:30–11:45, POT 251

Nontrivial topological phases in quantum mechanical many-body systems with gain and loss effects — •Marcel Klett, Holger Cartarius, and Guenter Wunner — 1. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart

Non-Hermitian PT-symmetric potentials are capable of effectively describing quantum systems with balanced in- and outfluxes. They allow for the existence of a PT-symmetric phase with purely real energy spectra of the non-Hermitian Hamiltonian. Recently a possible relation between the appearance of the PT-symmetric phase and topologically nontrivial states were found in two studies of simple model systems. However, they came to opposite conclusions. In the Su-Schrieffer-Heeger (SSH) model [1] the topological phase has a major influence. As soon as topologically nontrivial states appear PT symmetry gets broken. This is in contrast to the non-Hermitian Kitaev model [2], in which PT symmetry breaking does not depend on the topological phase. Our work is based on including different non-Hermitian potentials in the SSH model as well as the Kitaev model. We perform exact calculations of the eigenvalues and the eigenstates, clarify the relation between PT symmetry and topological phases, and explain why opposite results were found in the above mentioned systems.

[1] Baogang Zhu et al., Phys. Rev. A 89, 062102 (2014)*

[2] Xiaohui Wang et al., Phys. Rev. A 92, 012116 (2015)