  We studied the effects arising from a coherent source of photons on the
entanglement between excitons in a strained graphene monolayer. The graphene
layer was considered to be embedded in an imperfect optical microcavity. In our
investigation, we have studied the entanglement dynamics of systems consisting
of up to five excitons, which are treated as atomic-like qubits. Entangled
states of multiple qubits are useful in quantum error correction codes. We have
monitored the time evolution of the concurrence, three-$\pi$, mutual
information, and especially the negativity. We have demonstrated that coherent
pumping can create lasting entanglement between the excitons. However, the
entanglement only persists when the rate at which photons are pumped is smaller
than the decay rate of the cavity. Our results show that the degree in
entanglement between the excitons is increased with the intensity of the
strain-induced pseudomagnetic field in the graphene sheet. Additionally, we
have shown that a maximum amount of entanglement occurs at a finite number of
excitons in the system which depends on the parameters describing the
structure.
