Long Distance Cavity Entanglement by Entanglement Swapping Using Atomic   Momenta
  We propose a simple technique to generate entanglement between distant cavities by using entanglement swapping involving atomic momenta. For the proposed scheme, we have two identical atoms, both initially in their ground state, each incident on far apart cavities with particular initial momenta. The two cavities are prepared initially in superposition of zero and one photon state. First, we interact each atom with a cavity in dispersive way. The interaction results into atom-field entangled state. Then we perform EPR state measurement on both atomic momenta state which is an analog of Bell measurement. The EPR state measurement is designed by passing the atoms through cavity beam splitters which transfers the atomic momentum state into superposition state. Finally, these atoms are detected by the detector. After the detection of the atoms, we can distinguish that cavities in one of the Bell states. This process leads to two distant cavity fields entanglement. 
Sami Ul Haq and Aeysha Khalique
quant-ph