Connecting the Resource Theories of Purity and Coherence (Prof. Dagmar Bruss)
Jan 22, 2019
Prof. Dr. Dagmar Bruß
Institut für Theoretische Physik III, Universität Düsseldorf
Max-Planck-Institut für Quantenoptik
Hörsaal, Raum B 0.32 / New lecture hall, Room B 0.32
Max Planck Institute of Quantum Optics
The resource theory of quantum coherence studies the off-diagonal elements of a density matrix in a distinguished basis, whereas the resource theory of purity studies all deviations from the maximally mixed state. A direct connection between the two resource theories is established by identifying purity as the maximal coherence which is achievable by unitary operations. The states that saturate this maximum form a family of maximally coherent mixed states. Furthermore, purity bounds the maximal amount of entanglement and discord that can be generated by unitary operations, thus demonstrating that purity is the most elementary resource for quantum information processing.