Non-Hermitian scattering in SSH superconducting waveguides: exact Green-function reduction and dimerization-sensitive microwave functionalities

• URL: http://arxiv.org/abs/2606.10555v1
• Date: Tue, 09 Jun 2026 08:22:51 GMT
• Title: Non-Hermitian scattering in SSH superconducting waveguides: exact Green-function reduction and dimerization-sensitive microwave functionalities
• Abstract summary: Green-function theory for non-Hermitian single-microwave-photon scattering by finite superconducting circuit subsystems embedded in an SSH waveguide.<n>Results show how structured topological waveguides can be used not only to host scattering, but also to design non-Hermitian superconducting microwave functionalities.
• Score: 14.167952153585453
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We formulate an exact Green-function theory for non-Hermitian single-microwave-photon scattering by finite superconducting circuit subsystems embedded in an SSH waveguide. The structured SSH environment is integrated out exactly and enters the local scattering problem as an energy-dependent matrix self-energy, reducing the full open system to a finite-dimensional effective non-Hermitian Hamiltonian. This reduction places scattering amplitudes, exceptional-point diagnostics, coherent-perfect-absorption conditions, and lasing thresholds within one unified framework. Within this approach we analyze two superconducting devices. A flux-controlled two-qubit interferometric scatterer exhibits a broad bright branch and a narrow quasi-dark branch whose interference is reshaped by the SSH environment and changes qualitatively across the two dimerizations. A mediator-assisted two-qubit scatterer generates an additional energy-dependent complex coupling, reorganizes the dressed spectrum, and produces clearer dimerization-sensitive transparency-versus-absorption windows together with a pronounced separation between zero-like and pole-like scattering branches. In the active regime, near-exceptional-point hybridization enhances the pole-dominated response while deepening the singular-value valley associated with near-coherent perfect absorption. These results show how structured topological waveguides can be used not only to host scattering, but also to design non-Hermitian superconducting microwave functionalities.

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