We present a comprehensive implementation of the quantum trajectory theory
for the description of the entanglement dynamics in a Markovian open quantum
system made of two qubits. We introduce the average concurrence to characterize
the entanglement in the system and derive a deterministic evolution equation
for it that depends on the ways information is read from the environment. This
builded in flexibility of the method is used to address two actual issues in
quantum information: entanglement protection and entanglement estimation. We
identify general physical situations in which an entanglement protection
protocol based on local monitoring of the environment can be implemented.
Additionally, we methodically find unravelings of the system dynamics providing
analytical tight bounds for the unmonitored entanglement in the system at all
times. We conclude by showing the independence of the method on the choice of
entanglement measure.Comment: 15 pages, 4 figure
