Microwave‐Optics Entanglement Via Cavity Optomagnomechanics

Abstract

Microwave‐optics entanglement is a vital component for building hybrid quantum networks. Here, a new mechanism for preparing stationary entanglement between microwave and optical cavity fields in a cavity optomagnomechanical system is proposed. It consists of a magnon mode in a ferrimagnetic crystal that couples directly to a microwave cavity mode via the magnetic dipole interaction and indirectly to an optical cavity through the deformation displacement of the crystal. The mechanical displacement is induced by the magnetostrictive force and coupled to the optical cavity via radiation pressure. Both the opto‐ and magnomechanical couplings are dispersive. Magnon–phonon entanglement is created via magnomechanical parametric down‐conversion, which is further distributed to optical and microwave photons via simultaneous optomechanical beamsplitter interaction and electromagnonic state‐swap interaction, yielding stationary microwave‐optics entanglement. The microwave‐optics entanglement is robust against thermal noise, which will find broad potential applications in quantum networks and quantum information processing with hybrid quantum systems.

Cavity magnomechanics: from classical to quantum

“…The OMM system contains both the magno-and optomechanical interactions, which are both a dispersive type (in the case of ω b ≪ ω m ) and thus provide rich nonlinearities for, e.g. preparing various quantum states in the system [37,151,152]. A promising physical realization could adopt a micron sized YIG bridge structure [153], which supports a magnon mode with the frequency in gigahertz and a mechanical vibration mode with the frequency ranging from tens to hundreds of megahertz, thus possessing a dominant dispersive magnomechanical coupling (section 2).…”

“…The bare optomechanical coupling strength g cb is in the range of 10 2 -10 3 Hz for a micron-size mirror [155,156]. The bare magnomechanical coupling g mb is about tens of Hz for a micron-size YIG bridge [37] estimated using Hybrid OMM configurations adopted in [37,151,152,154] to realize magnon population detection [154], magnon state readout and optomagnonic entanglement [37], microwave-optics entanglement [151], and magnon-atomic ensemble entanglement [152]. (e) Microwave-to-optics transduction protocol using a linear coupling [162].…”

“…Instead, if the red-detuned magnon drive is replaced with a blue-detuned drive to activate the magnomechanical PDC interaction, stationary optomagnonic entanglement can be created [37]. Under these conditions, if by further coupling the magnon mode to a microwave cavity via the beam-splitter interaction [14,15] (forming an extended microwave cavity-OMM system, figure 14(c)), the above generated optomagnonic entanglement [37] can then be distributed to the microwave cavity, yielding stationary microwave-optics entanglement [151]. The microwave-optics entanglement finds particularly important applications in building a hybrid quantum network [157].…”

“…Hybrid systems based on magnomechanics. (a)-(d) Hybrid OMM configurations adopted in[37,151,152,154] to realize magnon population detection[154], magnon state readout and optomagnonic entanglement[37], microwave-optics entanglement[151], and magnon-atomic ensemble entanglement[152]. (e) Microwave-to-optics transduction protocol using a linear coupling[162].…”

Entanglement between indirectly coupled modes in a coupled opto-magnomechanical system

“…Such a system provides richer nonlinear interaction to support quantum protocols and exhibits potential applications in quantum information processing and quantum networks. For example, by introducing a microwave cavity and an atomic ensemble coupled to the magnon mode and optical cavity of the OMM respectively, one can prepare stationary microwave-optics entanglement and macroscopic atom-magnon entanglement [29,30]. In addition, recent work reported that the magnon population can be measured by the optical phase in the OMM system [31].…”