Polarization-dependent chiral transport and chiral solitons in spin Kitaev models

TL;DR

This paper introduces a new class of quantum spin models called spin Kitaev models, demonstrating polarization-dependent chiral transport and solitons, with potential applications in spintronics and quantum sensing, accessible through current experimental techniques.

Contribution

It proposes protocols to engineer spin Kitaev models using Floquet pulses, revealing novel chiral transport phenomena and solitons in spin systems.

Findings

Polarization-dependent chiral spin transport observed.

Large-spin limit maps to a nonlinear Hatano-Nelson model.

Magnetic field creates chiral solitonic molecules.

Abstract

Recent advances in synthetic quantum matter allow researchers to design quantum models inaccessible in traditional materials. Here, we propose protocols to engineer a new class of quantum spin models, which we call spin Kitaev models. The building blocks are basic spin-exchange interactions combined with locally selective Floquet pulses, a capability recently demonstrated in a range of experimental platforms. The resulting flip-flip and flop-flop terms lead to intriguing quantum transport dynamics beyond conventional spin models. For instance, in the absence of a magnetic field, spin excitations polarized along the $x$ and $y$ axes propagate chirally in opposite directions, producing polarization-dependent spin transport. In the large-spin limit, the spin Kitaev model maps to a nonlinear Hatano-Nelson model, where the interplay of nonlinearity and the underlying curvature yields polarization-dependent chiral solitons. A magnetic field binds two oppositely polarized chiral solitons into a chiral solitonic molecule, whose travel direction depends on its orientation. Our results, directly accessible in current experiments, open new opportunities for simulating transport in curved spaces and for applications in spintronics, information processing, and quantum sensing.