  In this work, a genuine mechanism of entanglement protection of a two-qubit
system interacting with a dissipative common reservoir is investigated. Based
on the generating of bound state for the system-reservoir, we show that
stronger bound state in the energy spectrum can be created by adding other
non-interacting qubits into the reservoir. In the next step, it is found that
obtaining higher degrees of boundedness in the energy spectrum leads to better
protection of two-qubit entanglement against the dissipative noises. Also, it
is figured out that the formation of bound state not only exclusively
determines the long time entanglement protection, irrespective to the Markovian
and non-Markovian dynamics, but also performs the task for reservoirs with
different spectral densities.
