Non-Hermitian Mott Skin Effect

TL;DR

This paper introduces the non-Hermitian Mott skin effect, a new boundary-sensitive phenomenon in strongly correlated quantum systems driven by non-Hermitian topology, affecting only spin degrees of freedom.

Contribution

It reveals a novel skin effect in non-Hermitian many-body systems caused by the interplay of correlations and topology, distinct from effects in non-interacting systems.

Findings

The Mott skin effect appears in strongly correlated bosonic chains.

Spin degrees of freedom show boundary sensitivity, charge does not.

Time evolution shows spin accumulation without charge redistribution.

Abstract

We propose a novel type of skin effects in non-Hermitian quantum many-body systems which we dub a non-Hermitian Mott skin effect. This phenomenon is induced by the interplay between strong correlations and the non-Hermitian point-gap topology. The Mott skin effect induces extreme sensitivity to the boundary conditions only in the spin degree of freedom (i.e., the charge distribution is not sensitive to boundary conditions), which is in sharp contrast to the ordinary non-Hermitian skin effect in non-interacting systems. Concretely, we elucidate that a bosonic non-Hermitian chain exhibits the Mott skin effect in the strongly correlated regime by closely examining an effective Hamiltonian. The emergence of the Mott skin effect is also supported by numerical diagonalization of the bosonic chain. The difference between the ordinary non-Hermitian skin effect and the Mott skin effect is also reflected in the time-evolution of physical quantities; under the time-evolution spin accumulation is observed while the charge distribution remains spatially uniform.