Quantum amplification of spin currents in cavity magnonics by a parametric drive induced long-lived mode

TL;DR

This paper demonstrates how a two-photon parametric drive in cavity magnonics can significantly amplify spin-current transfer between magnetic samples by inducing strong coherences and long-lived modes, with potential broader applications.

Contribution

It introduces a novel method of using parametric drives to enhance magnon-mediated spin transfer efficiency via long-lived modes and higher-order transitions.

Findings

Spin current transfer can be amplified by several orders of magnitude.

Parametric drive induces strong coherences and long-lived modes.

Enhancement is maximized near the stability boundary.

Abstract

Cavity-mediated magnon-magnon coupling can lead to a transfer of spin-wave excitations between two spatially separated magnetic samples. We enunciate how the application of a two-photon parametric drive to the cavity can lead to stark amplification in this transfer efficiency. The recurrent multiphoton absorption by the cavity opens up an infinite ladder of accessible energy levels, which can induce higher-order transitions within the magnon Fock space. This is reflected in a heightened spin-current response from one of the magnetic samples when the neighboring sample is coherently pumped. The enhancement induced by the parametric drive can be considerably high within the stable dynamical region. Specifically, near the periphery of the stability boundary, the spin current is amplified by several orders of magnitude. Such striking enhancement factors are attributed to the emergence of parametrically induced strong coherences precipitated by a long-lived mode. While contextualized in magnonics, the generality of the principle would allow applications to energy transfer between systems contained in parametric cavities.