Nonreciprocal quadrature squeezing in cavity–magnon optomechanics

Abstract

We investigate an intriguing scheme to realize nonreciprocal quadrature squeezing in a composite system comprising a cavity coupled to a mechanical oscillator, a degenerate parametric amplifier (DPA), and a yttrium iron garnet (YIG) sphere. Through numerical simulations, we analyze the quadrature squeezing spectrum for different coupling modes. In the case of only cavity mode, increasing the nonlinear gain of the DPA enhances not only both the amplitude of the fluctuations and the squeezing strength, but also induces frequency shifts at the normal mode frequencies. Under cavity–magnon coupling conditions, the Barnett effect is used to generate nonreciprocal quadrature squeezing spectrum. The cavity–magnon coupling induces normal mode splitting, with the spacing between the split spectral dips being linearly related to the coupling strength. The nonreciprocal quadrature squeezing properties at the two normal mode frequencies are opposite, and their nonreciprocal intensity increase with the Barnett effect. When both magnon mode and mechanical mode couplings with the cavity mode are considered, the number of squeezing dips increases to three, all exhibiting significant nonreciprocity under the Barnett effect. Our research may offer new perspectives for the development of nonreciprocal magnon devices and quantum precision measurement.