Quantum Lunch: The PPT^2 conjecture in dimension 3

Speaker: Alexander Müller-Hermes from QMATH

Title: The PPT^2 conjecture in dimension 3

Abstract:
Completely positive and completely co-positive maps (i.e. maps that stay completely positive even after composition with the matrix transposition) describe processes that are useless for quantum communication. However, some of these maps can still be used for private communication. Can a composition of two such maps still be useful for private communication? Here we show that this is not the case when the input and output system are of dimension 3. In this case the composition of two such maps is always entanglement breaking.