Excitonic skin effect

Wenhui Xu; Qi Zhou

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arXiv · 2508.20027

Excitonic skin effect

Wenhui Xu·Qi Zhou

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Abstract

We show that strong interactions combined with band-dependent imaginary vector potentials give rise to boundary localization of particle-hole pairs, which we term the excitonic skin effect. In a bilayer system with layer-specific gain/loss and an in-plane magnetic field, excitons experience a net imaginary vector potential, resulting in directional amplification of particle-hole pairs. Including nearest-neighbor interactions leads to a non-Hermitian bosonic Kitaev model, where the pairing effects grow exponentially with the size of the system, revealing a unique form of critical skin effect in interacting systems. Our framework applies to both atomic and electronic platforms and is directly testable in current experiments. These results also provide a route to explore non-Hermitian analogs of tensor gauge fields.

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Wenhui Xu, Qi Zhou. 2025-08-27. Excitonic skin effect. https://arxiv.org/abs/2508.20027

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