Dr. Eric Chitambar : Local Transformations of Quantum States Requiring Infinite Rounds of Classical Communication

Abstract

Despite its importance to quantum communication and entanglement theory, the class of Local Operations with Classical Communication (LOCC) still lacks a clear understanding. For instance, it is unknown the extent to which more rounds of measurement and communication can enhance the ability to perform certain tasks. We will investigate this question in the context of LOCC transformations between certain multipartite states and find that, indeed, the class of LOCC becomes strictly more powerful as more rounds of classical communication are permitted. Specially, for every n, there always exists an n round protocol that is impossible to implement in n - 2 rounds. Furthermore, I will describe certain entanglement transformations that are possible if and only if the protocol uses an infinite (unbounded) number of rounds. Interestingly, the number of rounds required to distill bipartite entanglement from particular multipartite states depends discontinuously on the amount of entanglement distilled.

Part of a MITACS seminar series.