  The fully quantized model of double qubits coupled to a common bath is solved
using the quantum state diffusion (QSD) approach in the non-Markovian regime.
We have established the explicit time-local non-Markovian QSD equations for the
two-qubit dissipative and dephasing models. Diffusive quantum trajectories are
applied to the entanglement estimation of two-qubit systems in a non-Markovian
regime. In both cases, non-Markovian features of entanglement evolution are
revealed through quantum diffusive unravellings in the system state space.
