Sub-Poissonian statistics and squeezing of magnons due to the Kerr effect in a hybrid coupled cavity–magnon system

Abstract

We investigate theoretically the quantum dynamics and statistics of magnons in a cavity–magnon system, where the magnons in a single yttrium iron garnet (YIG) sphere are coupled to microwave cavity photons. Under the rotating wave approximation, the Hamiltonian of the system is solved analytically. By using the coherent magnon state representation, we show that the magnon Kerr nonlinearity, which originates in the magnetocrystalline anisotropy in the YIG sample, could yield a periodic sub-Poissonian distribution and quadrature squeezing effects in the magnons. The generation and manipulation of these nonclassical quantum statistical properties of the magnons can be controlled by scaling the size of the YIG sample.