Occupation-dependent particle separation in one-dimensional non-Hermitian lattices

TL;DR

This paper demonstrates an occupation-dependent particle separation phenomenon in one-dimensional non-Hermitian lattices, revealing how particle pairing influences non-Hermitian skin effects and enables spatial separation of particles based on their occupation state.

Contribution

It introduces a novel occupation-dependent particle separation mechanism in non-Hermitian lattices, highlighting the role of particle pairing and interactions in shaping non-Hermitian skin effects and many-body eigenstate properties.

Findings

Pair particles in the same unit cell exhibit opposite non-Hermitian pumping directions.

Many-body eigenstates form separable clusters with different skin effect types.

Occupation-dependent skin effects enable spatial separation of paired and unpaired particles.

Abstract

We unveil an exotic phenomenon arising from the intricate interplay between non-Hermiticity and many-body physics, namely an occupation-dependent particle separation for hardcore bosons in a one-dimensional lattice driven by uni-directional non-Hermitian pumping. Taking hardcore bosons as an example, we find that a pair of particles occupying the same unit cell exhibit an opposite non-Hermitian pumping direction to that of unpaired ones occupying different unit cells. By turning on an intracell interaction, many-body eigenstates split in their real energies, forming separable clusters in the complex energy plane with either left-, right-, or bipolar-types of non-Hermitian skin effect (NHSE). The dependency of skin accumulating directions on particle occupation is further justified with local sublattice correlation and entanglement entropy of many-body eigenstates. Dynamically, this occupation-dependent NHSE manifests as uni- or bi-directional pumping for many-body initial states, allowing for spatially separating paired and unpaired particles. Similar phenomena also apply to fermionic systems, unveiling the possibility of designing and exploring novel non-Hermitian phases originated from particle non-conservation in subsystems (e.g., orbitals, sublattices, or spin species) and their spatial configurations.