Fig. 1. Schematic of Fabry-Perot cavity^[30].

Fig. 2. Cavity optomechanical systems with different mecha-nical vibration frequencies and masses^[39].

Fig. 3. Schematic of Fabry-Perot interferometer.

Fig. 4. Schematic of proposal from Vitali’s group^[43].

Fig. 5. Schematic of proposal from Bitarafan^[45].

Fig. 6. Experimental setup of F-P cavity with levitated particle^[47].

Fig. 7. Illustration of whispering gallery mode.

Fig. 8. (a) Structures of the first whispering gallery mode cavity^[48]; (b) its enhanced version^[49].

Fig. 9. Schematic of whispering gallery mode cavity formed by fiber taper and polymer wire^[51].

Fig. 10. Schematic of whispering gallery mode cavity formed by metal-doped material^[52].

Fig. 11. Schematic^[53](a) and experimental setup^[53](b) of proposal from Thompson’s group.

Fig. 12. Schematic of proposal from Sankey’s group^[54].

Fig. 13. Schematic of vibrating membrane cavity with two pumps^[55].

Fig. 14. Structure of zipper-like photonic crystal cavity^[57]

Fig. 15. Structures of (a) snowflake photonic crystal cavity^[58], (b) diamond NV center photonic crystal cavity^[59], and (c) hexagonal photonic crystal cavity^[61].

Fig. 16. Structures of (a) distributed superconducting microwave cavity^[62] and (b) drum-like superconducting microwave cavity^[63].

Fig. 17. Schematic (a) and structure (b) of Si₃N₄ membrane superconducting microwave cavity^[64].

Fig. 18. (a) Structure of membrane superconducting microwave cavity designed by Li et al.^[65]; (b) experimental setup designed by Bienfait et al.^[66].

Fig. 19. (a) Structure of quadrature hybrid coupler^[73]; (b) structure of 20 dB directional coupler^[73]; (c) schematic of microwave EPR state preparation^[74].

Fig. 20. Schematic of microwave continuous-variable entanglement state preparation proposed by Li et al.^[75].

Fig. 21. Structure of superconducting microwave cavity designed by Palomaki et al.^[76].

Fig. 22. Schematic of microwave squeezed state preparation and microwave-mechanical vibration mode entanglement preparation proposed by Sete et al.^[77].

Fig. 23. Schematic of preparing highly squeezed state in microwave domain^[78].

Fig. 24. Schematic of cavity electro-opto-mechanical system^[79].

Fig. 25. Schematic of cavity electro-opto-mechanical hybrid quantum interface proposed by Tian^[83].

Fig. 26. Schematic and structure of cavity electro-opto-mechanical converter designed by Andrews et al.^[84].

Fig. 27. Schematic of distant microwave fields entanglement preparation proposed by Abdi et al.^[85].

Fig. 28. Schematic of microwave quantum illumination based on double cavity electro-opto-mechanical converters^[79]

Fig. 29. Schematic of Gaussian and non-Gaussian microwave quantum states preparation based on cavity electro-opto-mechanical converter^[86].

Fig. 30. Schematic of cavity electro-opto-mechanical converter introducing optical parametric amplifier^[87].

Fig. 31. Schematic of quantum state transferring proposed by Regal’sgroup^[88].

Fig. 32. Schematic of multichannel quantum router based on cavity electro-opto-mechanical^[89].

Fig. 33. Schematic of heraldedmicrowave-optical entanglement preparation based on cavity electro-opto-mechanical system^[90].