Magnon squeezing in an antiferromagnet: Reducing the spin noise below the standard quantum limit

Abstract

The quantum squeezing of a collective spin-wave excitation (magnon) was investigated using femtosecond optical pulses. The quantum squeezed magnon was used to generate correlations involving pairs of spins in an antiferromagnetic insulator MnF2. It was found that the fluctutations of the magnetization of a crystallographic unit cell vary periodically in the squeezed state. The Fourier transform of the linear prediction (LP) fit to the time-domain compared well with the measured two-magnon Raman spectrum.