Lower Bound of Concurrence and Distillation for Arbitrary Dimensional   Bipartite Quantum States
  We present a lower bound of concurrence for arbitrary dimensional bipartite quantum states. This lower bound may be used to improve all the known lower bounds of concurrence. Moreover, the lower bound gives rise to an operational sufficient criterion of distillability of quantum entanglement. The significance of our result is illustrated by quantitative evaluation of entanglement for entangled states that fail to be identified by the usual concurrence estimation method, and by showing the distillability of mixed states that can not be recognized by other distillability criteria. 
Ming-Jing Zhao, Xue-Na Zhu, Shao-Ming Fei and Xianqing Li-Jost
quant-ph