Nonreciprocal mechanical squeezing in cavity magnomechanics

We propose a scheme to achieve nonreciprocal mechanical squeezing in a hybrid Kerr-modified cavity magnomechanical system, where the magnon mode is driven by two-tone microwave fields. The nonreciprocity originates from the magnon Kerr effect. Strong mechanical squeezing beyond the 3 dB limit can be nonreciprocally generated by adjusting the magnon frequency detuning, effective magnomechanical coupling strength, as well as the damping of the oscillator and the dissipation of the cavity. Importantly, the proposed scheme is robust against environmental thermal noise and system dissipation, ensuring its feasibility under current experimental conditions. This work may pave the way for the development of nonreciprocal quantum devices, such as isolators and circulators. Furthermore, the ability to achieve such robust mechanical squeezing has significant implications for advancing quantum precision measurements in metrology and sensing, offering new opportunities for exploring quantum-enhanced technologies.