Complete Entanglement Witness for Quantum Teleportation
  We propose a set of linear quantum entanglement witnesses constituted by local quantum-mechanical observables with each two possible measurement outcomes. These witnesses detect all the entangled resources which give rise to a better fidelity than separable states in quantum teleportation and present both sufficient and necessary conditions in experimentally detecting the useful resources for quantum teleportation. 
Ming-Jing Zhao, Shao-Ming Fei and Xianqing Li-Jost
quant-ph