Versatile braiding of non-hermitian topological edge states
Among the most intriguing features of non-Hermitian (NH) systems is the ability of complex energies to form braids under parametric variation. Several braiding behaviors, including link and knot formation, have been observed in experiments on synthetic NH systems, such as looped optical fibers. T...
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Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
2025
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Subjects: | |
Online Access: | https://hdl.handle.net/10356/182165 |
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Institution: | Nanyang Technological University |
Language: | English |
Summary: | Among the most intriguing features of non-Hermitian (NH) systems is the
ability of complex energies to form braids under parametric variation. Several
braiding behaviors, including link and knot formation, have been observed in
experiments on synthetic NH systems, such as looped optical fibers. The exact
conditions for these phenomena remain unsettled, but existing demonstrations
have involved long-range nonreciprocal hoppings, which are hard to implement on
many experimental platforms. Here, we present a route to realizing complex
energy braids using 1D NH Aubry-Andr\'e-Harper lattices. Under purely local
gain and loss modulation, the eigenstates exhibit a variety of braiding
behaviors, including unknots, Hopf links, trefoil knots, Solomon links and
catenanes. We show how these are created by the interplay between
non-Hermiticity and the lattice's bulk states and topological edge states. The
transitions between different braids are marked by changes in the global Berry
phase of the NH lattice. |
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