Entanglement evolution and distillation under a local magnetic pulse

In this Letter, we propose a scheme to control and distill the entanglement of two separated systems by modulating a local oscillating field which is used to create coherent superposition in one of the two systems. We show, as long as the entanglement is non-zero, the entanglement can be modulated to reach a maximum with a certain probability via an appropriate choice of tuning period and radio magnitude. The dynamics of the entanglement and the efficiency are study in an exact way.