The entropy squeezing properties of different types of moving three-level atoms coupled with a single-mode coherent field are studied. The influences of the moving velocity and initial states of the three-level atom on the entropy squeezing are discussed. The results show that, the entropy squeezing properties of the three-level atom depend on its initial state, moving velocity, and the type. A stationary three-level atom can not obtain a steady entropy squeezing whatever initial conditions are chosen, while a moving three-level atom can achieve a steady and optimal entropy squeezing through choosing higher velocity and appropriate initial state. Our result provides a simple method for preparing squeezing resources with ultra-low quantum noise of the three-level atomic system without additional any complex techniques.

The protection of the entanglement between two V-atoms (EBTVA) in a multi-cavity coupling system is studied. The whole system consists of two V-atoms. The two V-atoms are initially in the maximum entangled state and interacts locally with its own dissipative cavity which is coupled to the external cavities with high quality factor (ECWHQF). The results show that, when there is no ECWHQF, the EBTVA can be protected effectively in the case where the V-atom and the dissipative cavity are weak coupled in large detuning, while when there are different numbers n of ECWHQF coupled to two dissipative cavities, by adjusting the parameters of the number n of ECWHQF and the coupling strength k between cavities, the EBTVA can be protected perfectly and continuously. Our result provides an effective method for protecting entanglement resources of three-level system.