Entanglement control via coherent population trapping in the closed –loop quantum systems

In this research, the disentanglement conditions between the coated atom and its spontaneous emission in double- lambda quantum system was investigated. Initially, the entanglement increased due to the interaction between the laser fields and the four- level atom. This entanglement can be controlled by changing the intensity of the applied fields. By applying the two coupling fields, the system is entangled and the system would be disentangled with one coupling field and one probe field. The present research demonstrated that spontaneous emission by changing the population of atoms in the alignments is a good source of entanglement, but fields were manipulated in such a way that this entanglement was reduced by coherent trapping of the population for the atoms.