Interactions and tilt induced non-Hermitian Mott Skin effect

Muhammad Hasan^1*, Hsiang-Hua Jen¹, Jhih-Shih You²

¹Institute of Atomic and Molecular Sciences,, Academia Sinica, Taipei, Taiwan
²National Taiwan Normal University, Taipei, Taiwan

* Presenter:Muhammad Hasan, email:mshasan.official@gmail.com

We study the interplay between interactions and non-Hermitian skin effects in a nonequilibrium asymmetric two-component bosonic system with purely real on-site and inter-species interactions and open boundary conditions. In non-interacting systems, we observe that real interactions do not qualitatively modify the skin effect. The eigenspectrum remains purely real, though particles continue to localise at the lattice edge, and the many-body state no longer exhibits the characteristic features like complex spectral transitions—induced by imaginary interactions. Strikingly, if we selectively add a Stark potential to one of the components, we observe richer, state-dependent behaviour. On the lower-lying eigenstates, the global density remains homogeneous while the spin density exhibits systematic spatial inversion, flipping from edge to edge. This hierarchical pattern degrades in higher-lying states, when the density profile is not homogeneous. Our findings demonstrate how real interactions preserve the skin effect, but an added Stark potential can create a rich hierarchy of spatial structures, revealing the action of external fields in non-Hermitian many-body localisation.

Keywords: Non-Hermitian system, Exact Diagonalisation, Skin-effect, Stark potential