Transmitting squeezed states in a cascaded cavity-magnonic system

The squeezed state has wide applications in quantum information and metrology. This work demonstrates the long-distance transmission of a squeezed state, where we utilize a cavity-magnonic system composed of a cascaded cavity and a yttrium iron garnet sphere. The squeezed source, originating from a flux-driven Josephson parametric amplifier, is mediated through six cavity modes and ultimately transmitted to magnon mode. With appropriate detuning matching, state transmission can be blocked at any mode, and the difference in squeezing phase between adjacent modes is π. Squeezed magnons exhibit high robustness against environmental temperature and magnetic damping. Our work provides prior guidance for multi-mode transmission of quantum states in continuous variable systems.