Optimal amount of entanglement to distinguish quantum states   instantaneously
  We introduce a new aspect of nonlocality which arises when the task of quantum states distinguishability is considered under local operations and shared entanglement in the absence of classical communication. We find the optimal amount of entanglement required to accomplish the task perfectly for sets of orthogonal states and argue that it quantifies information nonlocality. 
Berry Groisman and Sergii Strelchuk
quant-ph