  Entanglement is a key issue in the quantum physics which gives rise to
resources for achieving tasks that are not possible within the realm of
classical physics. Quantum entanglement varies with the evolution of the
quantum systems. It is of significance to investigate the entanglement dynamics
in terms of quantum channels. We study the entanglement-breaking channels and
present the necessary and sufficient conditions for a quantum channel to an
entanglement-breaking one for qubit systems. Furthermore, a concept of strong
entanglement-breaking channel is introduced. The amendment of
entanglement-breaking channels is also studied.
