Physical Review A
Quantum communication, Information theory -- Data processing
We give a conceptually simple necessary condition such that a separable quantum operation can be implemented by local operations on subsystems and classical communication between parties (LOCC), a condition which follows from a novel approach to understanding LOCC. This necessary condition applies to all LOCC protocols involving any number of parties and any finite number of rounds of communication. Furthermore, it demonstrates an extremely strong difference between separable operations and LOCC, in that there exist examples of the former for which the condition is extensively violated. More precisely, the violation by separable operations of our necessary condition for LOCC grows without limit as the number of parties increases.
Cohen, S. M. (2013). Necessary Condition for Local Quantum Operations and Classical Communication with Extensive Violation by Separable Operations. Physical Review A, 90, 012336.