Bulk spectra and the non-Hermitian skin effect in systems with long-range couplings

• URL: http://arxiv.org/abs/2607.24496v1
• Date: Mon, 27 Jul 2026 14:31:56 GMT
• Title: Bulk spectra and the non-Hermitian skin effect in systems with long-range couplings
• Abstract summary: We compare the two methods on the basis of one-dimensional quantum emitter chains in free space and when coupled to a waveguide.<n>We find that only periodic boundary conditions lead to physically and mathematically robust results, while the infinite-chain approach entails convergence issues.<n>In addition, the waveguide system yields unusual findings like a non-star shaped generalized Brillouin zone and strongly localized eigenstates with zero winding number.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: To achieve translational symmetry for the computation of the band structure of a lattice model, one can either consider an infinite lattice or impose periodic boundary conditions. While in sys- tems with short-range couplings these two approaches are equivalent, we show that for long-range couplings one can obtain considerably different results. We compare the two methods on the basis of one-dimensional quantum emitter chains both in free space and when coupled to a waveguide. The latter system allows for asymmetric couplings enabling the non-Hermitian skin effect, which we analyze using the two different band-structure calculation methods. We find that only periodic boundary conditions lead to physically and mathematically robust results, while the infinite-chain approach entails convergence issues and is unable to satisfyingly explain the emergence of the non- Hermitian skin effect in the waveguide system. In addition, the waveguide system yields unusual findings like a non-star shaped generalized Brillouin zone and strongly localized eigenstates with zero winding number.

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