Macroscopic entanglement between two magnon modes via two-tone driving of a superconducting qubit

TL;DR

This paper proposes a method to generate and verify macroscopic entanglement between two magnon modes in YIG spheres using a superconducting qubit driven by two tones, with feasible parameters and potential for fundamental quantum studies.

Contribution

It introduces a scheme to entangle two magnon modes via two-tone driving of a superconducting qubit, enabling macroscopic quantum state preparation with current technology.

Findings

Strong entanglement achievable with feasible parameters.

Detection scheme for verifying magnon entanglement.

Macroscopic entanglement involving over 10^18 spins demonstrated.

Abstract

The cavity-mediated coupling between magnons in an yttrium-iron-garnet (YIG) sphere and a superconducting qubit has recently been demonstrated as a new platform for preparing macroscopic quantum states. Here, based on this system, we propose to entangle two magnon modes in two YIG spheres by driving the qubit with a two-tone field and by appropriately choosing the frequencies and strengths of the two driving fields. We show that strong entanglement can be achieved with fully feasible parameters. We further provide a detection scheme for experimentally verifying the entanglement. Our results indicate that macroscopic entanglement between two magnon modes in two millimeter-sized YIG spheres, involving more than $10^{18}$ spins, can be realized using currently available parameters, which finds promising applications in fundamental studies, such as macroscopic quantum mechanics and the test of unconventional decoherence theories.