SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 64: Topology: Other Topics
TT 64.6: Vortrag
Freitag, 31. März 2023, 10:45–11:00, HSZ 201
Non-Hermitian diamond chain — •Carolina Martinez Strasser1, Miguel Ángel Jimenez Herrera1, and Dario Bercioux2 — 1Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain — 2Ikerbasque, Basque Foundation for Science, Plaza Euskadi 5 48009 Bilbao, Spain
We investigate the spectral properties of a non-Hermitian quasi-one-dimensional lattice in several possible dimerization configurations. Specifically, we focus on a non-Hermitian diamond chain that presents a zero-energy flat band. In the Hermitian case, this flat band originates from wave interference and results in a wave function localized only on a subset of sites on the unit cell [1]. We transform the system into a non-Hermitian one by considering asymmetric hopping terms between some of the lattice sites of the chain. This leads to the accumulation of eigenstates, known as the skin effect. Despite this accumulation of eigenstates, we can characterize the presence of non-trivial edge states at zero energy by a real-space topological invariant known as biorthogonal polarization. We show that this invariant, evaluated using the destructive interference method, can also characterize the non-trivial phase of the non-Hermitian diamond chain [2].
[1] D. Bercioux, O. Dutta, and E. Rico, Ann. Phys. (Berl.) 529, 1600262 (2017)
[2] F. K. Kunst et al., Phys. Rev. Lett. 121, 026808 (2018)