Biorthogonal scattering and generalized unitarity in non-Hermitian systems

Fuente: arXiv
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Auteurs principaux: Ryu, Jung-Wan, Schomerus, Henning, Park, Hee Chul
Format: Preprint
Publié: 2026
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author Ryu, Jung-Wan
Schomerus, Henning
Park, Hee Chul
author_facet Ryu, Jung-Wan
Schomerus, Henning
Park, Hee Chul
contents We investigate the two-port scattering process in non-Hermitian dimer models via quantum measurements using external leads. We focus on two exemplary dimer models that preserve parity-time symmetry via spatial gain-loss balance and exhibit non-reciprocity due to directional hopping. The scattering matrix is constructed using the biorthogonality of the left and right scattering states of the Hamiltonian, allowing us to calculate the reflection and transmission probabilities. Our analysis compares the reflection and transmission coefficients derived from the left, right, and combined scattering states, revealing that, unlike in Hermitian systems, the non-Hermitian scattering process does not adhere to unitarity when considering only the right scattering states. Furthermore, non-Hermitian scattering can enhance the reflection and transmission probabilities, with distinct physical contributions arising independently from complex eigenvalues and the non-orthogonality of eigenstates. Our results clarify how biorthogonality restores generalized unitarity and identify distinct physical origins of enhanced transport in PT-symmetric and non-reciprocal dimers, providing new insights into quantum transport in non-Hermitian systems.
format Preprint
id arxiv_https___arxiv_org_abs_2602_06349
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Biorthogonal scattering and generalized unitarity in non-Hermitian systems
Ryu, Jung-Wan
Schomerus, Henning
Park, Hee Chul
Mesoscale and Nanoscale Physics
Quantum Physics
We investigate the two-port scattering process in non-Hermitian dimer models via quantum measurements using external leads. We focus on two exemplary dimer models that preserve parity-time symmetry via spatial gain-loss balance and exhibit non-reciprocity due to directional hopping. The scattering matrix is constructed using the biorthogonality of the left and right scattering states of the Hamiltonian, allowing us to calculate the reflection and transmission probabilities. Our analysis compares the reflection and transmission coefficients derived from the left, right, and combined scattering states, revealing that, unlike in Hermitian systems, the non-Hermitian scattering process does not adhere to unitarity when considering only the right scattering states. Furthermore, non-Hermitian scattering can enhance the reflection and transmission probabilities, with distinct physical contributions arising independently from complex eigenvalues and the non-orthogonality of eigenstates. Our results clarify how biorthogonality restores generalized unitarity and identify distinct physical origins of enhanced transport in PT-symmetric and non-reciprocal dimers, providing new insights into quantum transport in non-Hermitian systems.
title Biorthogonal scattering and generalized unitarity in non-Hermitian systems
topic Mesoscale and Nanoscale Physics
Quantum Physics
url https://arxiv.org/abs/2602.06349