PhD Defense Christian Majenz – University of Copenhagen

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PhD Defense Christian Majenz

Titel: Entropy in Quantum Information Theory - Communication and Cryptography

Abstract: Entropies have been immensely useful in information theory. In this Thesis, several results in quantum information theory are collected, most of which use entropy as the main mathematical tool. The four topics, entropy inequalities, one-shot quantum source coding via catalytic decoupling, lower bounds for the resource reqirements for port-based teleportation and non-malleability and authentication for quantum private key encryption, will first be presented in a high level language. Afterwards, the last topic will be explained in more detail. In particular, It will be explained how the previously known definition of quantum non-malleability allows for a certain attack, how the new definition prevents this attack. It will also be shown that non-malleable quantum encryption schemes can be used to build quantum authentication schemes, and the relationship between different notions of quantum authentication will be clarified.

Supervisors:  Prof. Matthias Christandl, University of Copenhagen

Assessment committee:

Prof Bergfinnur Durhuus (Chairman), MATH

Ass. Prof. Omar Fawzi, ENS Lyon

CNRS Senior Researcher, Iordanis Kerenidis, University Paris Diderot 7