On the Relation between Quantum Discord and Purified Entanglement

• Main Author: Webster, Eric
• Language: en
• Published: 2013
• Subjects: quantum; discord; entanglement; information; Applied Mathematics (Quantum Information)
• Online Access: http://hdl.handle.net/10012/7798

In this thesis, I study bipartite discord between A and B in terms of the structure formed by the bipartite and tripartite entanglement found in the purified system ABC. I find that discord manifests itself only when there is both tripartite and bipartite entanglement present in the purification. This allows one to understand the asymmetry of quantum discord, D(A|B) ≠ D(B|A) in terms of entanglement monogamy. For the cases where AB has rank two and for two-mode Gaussian states, I find that discord also necessarily appears whenever there is tripartite and bipartite entanglement in ABC. As a result of this, some light is shed on a counter-intuitive property of Gaussian states: the presence of classical correlations necessarily requires the presence of quantum discord. Finally, these results are found to be closely linked to the protocol for remote activation of entanglement by a third party.