Steady entangled-state generation via cross-Kerr effect in a ferrimagnetic crystal

TL;DR

This paper proposes a method to generate steady entangled magnon states in a ferrimagnetic crystal using cross-Kerr nonlinearities, with potential applications in quantum information processing.

Contribution

It introduces a scheme for entangling magnon modes via cross-Kerr effects in a solid-state system, considering inhomogeneous bias fields and coexistence of nonlinearities.

Findings

Quantum entanglement persists at steady state under realistic conditions.

Entangled states are more robust when self-Kerr and cross-Kerr nonlinearities coexist.

Numerical results demonstrate feasibility with experimental parameters.

Abstract

For solid-state spin systems, the collective spin motion in a single crystal embodies multiple magnetostatic modes. Recently, it was found that the cross-Kerr interaction between the higher-order magnetostatic mode and the Kittel mode introduces a new operable degree of freedom. In this work, we propose a scheme to entangle two magnon modes via the cross-Kerr nonlinearity when the bias field is inhomogeneous and the system is driven. Quantum entanglement persists at the steady state, as demonstrated by numerical results using experimentally feasible parameters. Furthermore, we also demonstrate that entangled states can survive better in the system where self-Kerr and cross-Kerr nonlinearities coexist. Our work provides insights and guidance for designing experiments to observe entanglement between different degrees of freedom within a single ferrimagnetic crystal. Additionally, it may stimulate potential applications in quantum information processing using spintronic devices.