Abstract
We consider time-evolution of the disentanglement process of once generated entangled qubit pair as a result of the phase variation of the pumping field. As a source of maximally entangled states we use the nonlinear coupler (two oscillators with Kerr-like nonlinearities) with nonlinear internal interactions. The coupler prepared in a maximally entangled state interacts afterwards with external reservoir of thermal character and pumping field as well. We show that the fact of the coupling with additional state (which can create additional entanglement with one of the 2-qubit system's previously entangled states) is an origin of interesting entanglement decay behaviour. We can observe shortening of both: entanglement death-time and entanglement birth caused by changing the phase of an external driving field.