分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： We show how to prepare macroscopic entanglement between an atomic ensemble and a large number of magnons in a ferrimagnetic YIG crystal. Specifically, we adopt an opto-magnomechanical configuration where the magnetostriction-induced magnomechanical displacement couples to an optical cavity via radiation pressure, and the latter further couples to an ensemble of two-level atoms that are placed inside the cavity. We show that by properly driving the cavity and magnon modes, optomechanical entanglement is created which is further distributed to the atomic and magnonic systems, yielding stationary entanglement between atoms and magnons. The atom-magnon entanglement is a result of the combined effect of opto- and magnomechanical cooling and optomechanical parametric down-conversion interactions. A competition mechanism between two mechanical cooling channels is revealed. Our results indicate that the hybrid opto-magnomechanical system may become a promising system for preparing macroscopic quantum states involving magnons, photons, phonons and atoms.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Cooling the motion of a massive mechanical oscillator into its quantum ground state plays an essential role in observing macroscopic quantum effects in mechanical systems. Here we propose a measurement-based feedback cooling protocol in cavity magnomechanics that is able to cool the mechanical vibration mode of a macroscopic ferromagnet into its ground state. The mechanical mode couples to a magnon mode via a dispersive magnetostrictive interaction, and the latter further couples to a microwave cavity mode via the magnetic-dipole interaction. A feedback loop is introduced by measuring the amplitude of the microwave cavity output field and applying a force onto the mechanical oscillator that is proportional to the amplitude fluctuation of the output field. We show that by properly designing the feedback gain, the mechanical damping rate can be significantly enhanced while the mechanical frequency remains unaffected. Consequently, the vibration mode can be cooled into its quantum ground state in the unresolved-sideband regime at cryogenic temperatures. The protocol is designed for cavity magnomechanical systems using ferromagnetic materials which possess strong magnetostriction along with large magnon dissipation.
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