AI Article Synopsis
- Non-Hermitian systems challenge traditional theories by showing that bulk properties do not always predict boundary states, particularly at parameter values away from gap closings.
- A new framework based on biorthogonal quantum mechanics reveals that boundary modes' combined properties only affect bulk behavior during phase transitions.
- The study provides a generalized bulk-boundary correspondence and quantized polarization, illustrated through various models, including non-Hermitian versions of the Su-Schrieffer-Heeger model and Chern insulators.
Article Abstract
Non-Hermitian systems exhibit striking exceptions from the paradigmatic bulk-boundary correspondence, including the failure of bulk Bloch band invariants in predicting boundary states and the (dis)appearance of boundary states at parameter values far from those corresponding to gap closings in periodic systems without boundaries. Here, we provide a comprehensive framework to unravel this disparity based on the notion of biorthogonal quantum mechanics: While the properties of the left and right eigenstates corresponding to boundary modes are individually decoupled from the bulk physics in non-Hermitian systems, their combined biorthogonal density penetrates the bulk precisely when phase transitions occur. This leads to generalized bulk-boundary correspondence and a quantized biorthogonal polarization that is formulated directly in systems with open boundaries. We illustrate our general insights by deriving the phase diagram for several microscopic open boundary models, including exactly solvable non-Hermitian extensions of the Su-Schrieffer-Heeger model and Chern insulators.
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| http://dx.doi.org/10.1103/PhysRevLett.121.026808 | DOI Listing |
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