Feedback-enhanced distant entanglement of magnon and phonon modes with atomic ensembles in coupled cavities

TL;DR

This paper demonstrates that a coherent feedback loop significantly enhances and stabilizes distant bipartite entanglement among cavity photons, atomic ensembles, magnons, and phonons in a coupled cavity system, advancing quantum network capabilities.

Contribution

The study introduces a feedback-enhanced scheme that markedly improves bipartite entanglement strength, robustness, and parameter space in a multi-mode coupled cavity system with atomic and magnon-phonon modes.

Findings

CFL significantly boosts bipartite entanglement levels.

Entanglement becomes more robust against thermal noise.

Enhanced parameter space for strong entanglement.

Abstract

The generation and manipulation of distant entanglement between disparate systems is crucial for various quantum technologies. In this work, we investigate a system of coupled cavities comprising an ensemble in cavity-1, a yttrium-iron-garnet (YIG) sphere in cavity-2, and a coherent feedback loop (CFL) that feeds the output of cavity-1 back into cavity-1 through a beam splitter. This system features five excitation modes: cavity-1 photons, atomic ensemble, cavity-2 photons, the magnon, and phonon modes of the YIG sphere. Thus various combinations of bipartite entanglements can be studied. Our main focus is the study of various combinations of distant bipartite entanglements, especially the entanglement of the atomic ensemble and photons in cavity-1 with the magnon and phonon modes of the YIG sphere in cavity-2. Compared to the previously reported results, introducing a CFL significantly enhances all the bipartite entanglements. Besides, the degree of entanglement of various modes, the parameters space, where the strong entanglement exists, is also significantly enhanced due to CFL. Moreover, the entanglement is more robust against thermal noise. We believe our results are important for quantum technologies where the distribution of entanglement on quantum networks is crucial.