Controlling the non-classical properties of a hybrid Cooper pair box system and an intensity dependent nanomechanical resonator

• The work treats a hybrid system (CPB–NR) via the Buck–Sukumar model.
• Quantum entropy and excitation–inversion are focused.
• System evolution in presence of losses is considered.

The present work refers to a somewhat realistic treatment to investigate the entropy and the excitation–inversion of a coupled system that consists of a nanomechanical resonator and a superconducting Cooper pair box. The procedure uses the Buck–Sukumar model in the microwave domain and considers the nanoresonator with a time-dependent frequency as well as both subsystems in the presence of losses. The results were obtained for the temporal evolutions of the entropy of each subsystem and the excitation–inversion of the Cooper pair box. A comparison about which of these two subsystems is more sensitive to the presence of losses was done. The results suggest that appropriate choices of the time-dependent parameters can help us to monitor these properties of the subsystems and may offer potential applications, e.g., in the generation of non-classical states, quantum communication, and quantum lithography.