  Logic-qubit entanglement is a promising resource in quantum information
processing, especially in future large-scale quantum networks. In the paper, we
put forward an efficient entanglement purification protocol (EPP) for nonlocal
mixed logic entangled states with the bit-flip error in the logic qubits of the
logic Bell state, resorting to the photon-atom interaction in low-quality (Q)
cavity and atomic state measurement. Different from existing EPPs, this
protocol can also purify the logic phase-flip error, and the bit-flip error and
the phase-flip error in physic qubit. During the protocol, we only require to
measure the atom states, and it is useful for improving the entanglement of
photon systems in future large-scale quantum networks.
