Entropy in Quantum Information Theory -- Communication and Cryptography

Understand

In this Thesis, several results in quantum information theory are collected, most of which use entropy as the main mathematical tool.

• *While a direct generalization of the Shannon entropy to density matrices, the von Neumann entropy behaves differently.
• A long-standing open question is, whether there are quantum analogues of unconstrained non-Shannon type inequalities.
• Here, a new constrained non-von-Neumann type inequality is proven, a step towards a conjectured unconstrained inequality by Linden and Winter.