# Quantum drives produce strong entanglement between YIG samples without using intrinsic nonlinearities

## TL;DR

This paper demonstrates a novel method to generate strong entanglement between YIG samples in a cavity-magnon system without relying on weak nonlinearities, using a weak squeezed vacuum drive instead.

## Contribution

The authors introduce a scheme that produces entanglement between YIG samples without the need for intrinsic nonlinearities, utilizing a squeezed vacuum drive via a Josephson parametric amplifier.

## Key findings

- Significant entanglement achieved with modest squeezing levels.
- Entanglement remains robust against temperature variations.
- Optimal parameters identified for maximizing entanglement.

## Abstract

We show how to generate an entangled pair of yttrium iron garnet (YIG) samples in a cavity-magnon system without using any nonlinearities which are typically very weak. This is against the conventional wisdom which necessarily requires strong Kerr like nonlinearity. Our key idea, which leads to entanglement, is to drive the cavity by a weak squeezed vacuum field generated by a flux-driven Josephson parametric amplifier (JPA). The two YIG samples interact via the cavity. For modest values of the squeezing of the pump, we obtain significant entanglement. This is the principal feature of our scheme. We discuss entanglement between macroscopic spheres using several different quantitative criteria. We show the optimal parameter regimes for obtaining entanglement which is robust against temperature. We also discuss squeezing of the collective magnon variables.