Abstract: We propose an entanglement purification scheme based on material qubits�
and ancillary coherent multiphoton states. We consider a typical QED�
scenario where material qubits implemented by two-level atoms fly�
sequentially through a cavity and interact resonantly with a single-mode�
of the radiation field. We explore the theoretical possibilities of�
realizing a high-fidelity two-qubit quantum operation necessary for the�
purification protocol with the help of a postselective balanced homodyne�
photodetection. We demonstrate that the obtained probabilistic quantum�
operation can be used as a bilateral operation in the proposed�
purification scheme. It is shown that the probabilistic nature of this�
quantum operation is counterbalanced in the last step of the scheme�
where qubits are not discarded after inadequate qubit measurements. As�
this protocol requires present-day experimental setups and generates�
high fidelity entangled pairs with high repetition rates, it may offer�
interesting perspectives for applications in quantum information theory.