Correlations in quantum information protocols.

Abstract

In this thesis I present four works developed in collaboration during my PhD. The main topic in them was the study of correlations in quantum information protocols with particular emphasis in quantum discord and entanglement. In the article entitled Quantum Discord Underlies the Optimal Scheme for Modifying the Overlap between Two States J. Phys. Soc. Jpn. 83, 044006 (2014), we focused on quantum discord in the context of overlap modification between two non-orthogonal states. We showed that only discord is necessary to assist the probabilistic and deterministic protocols for overlap modification. In the article entitled A measure for maximum similarity between outcome states EPL, 109, 40001 (2015), we developed a new correlation, similarity degree (SD). Like discord, this quantity characterizes the effect of a local measurement on the other subsystem. We find and analytical expression to calculate it. Addionally, it can be directly measured in an optical setup.