  We explore the possibility of the controlled manipulation of the entanglement
of two qubits with an external apparatus, the Rabi Hamiltonian. The novel
results show that the initially entangled two qubits could have very high
probability to stay unchanged by the coherent state of the photon with chosen
parameters. If the inter-qubit coupling strength is negative, their
entanglement could be kept for a much longer time by a relatively strong
external quantum control with the suitable and novel choice of some parameters.
Furthermore, their entanglement will not show any sudden death and revival. All
these results are different from the previous studies and they are given with
reasonable explanations. The maintaining of the entanglement of the two qubits
with very high fidelity will be very helpful for the quantum information
process.
