UltraLow Threshold Phonon Laser in a PT$\mathcal {PT}$‐Symmetric Cavity Magnomechanical System

Abstract The magnomechanical interaction arises from the coupling between magnons and phonons, an effect that has attracted significant attention. Leveraging this foundation, an ultralow threshold phonon laser within a parity‐time ()‐symmetric cavity magnomechanical (CMM) system is investigated. The ‐symmetry is achieved by incorporating a gain mechanism into the cavity mode and the amplification of phonon excitation number is achieved through the pumping of magnon mode. As the gain and dissipation approach the equilibrium, the mechanical gain undergoes a notable amplification, giving rise to a phonon laser action characterized by an ultralow threshold condition. This finding not only promotes a cross‐disciplinary approach in fields such as non‐Hermitian physics and quantum magnomechanics but also points to a promising path for enhancing the magnomechanical effect.