Heralded Quantum Entanglement between Distant Matter Qubits
  We propose a scheme to realize heralded quantum entanglement between two distant matter qubits using two $\Lambda$ atom systems. Our proposal does not need any photon interference. We also present a general theory of outcome state of non-monochromatic incident light and finite interaction time. 
W-J Yang and Xiang-Bin Wang
quant-ph