Remote magnon entanglement between two massive ferrimagnetic spheres via cavity optomagnonics

Abstract

Recent studies show that hybrid quantum systems based on magnonics provide a\nnew and promising platform for generating macroscopic quantum states involving\na large number of spins. Here we show how to entangle two magnon modes in two\nmassive yttrium-iron-garnet (YIG) spheres using cavity optomagnonics, where\nmagnons couple to high-quality optical whispering gallery modes supported by\nthe YIG sphere. The spheres can be as large as 1 mm in diameter and each sphere\ncontains more than $10^{18}$ spins. The proposal is based on the asymmetry of\nthe Stokes and anti-Stokes sidebands generated by the magnon-induced Brillouin\nlight scattering in cavity optomagnonics. This allows one to utilize the Stokes\nand anti-Stokes scattering process, respectively, for generating and verifying\nthe entanglement. Our work indicates that cavity optomagnonics could be a\npromising system for preparing macroscopic quantum states.\n