Publications Repository - Gdańsk University of Technology

Based on state and channel isomorphism we point out that semidefiniteprogramming can be used as a quick test for nonzero one-way quantum channelcapacity. This can be achieved by searching for symmetric extensions of statesisomorphic to a given quantum channel. With this method we provide examplesof quantum channels that can lead to high entanglement transmission but stillhave zero one-way capacity, in particular, regions of symmetric extendibilityfor isotropic states in arbitrary dimensions are presented. Further, we derivea new entanglement parameter based on (normalized) relative entropy distanceto the set of states that have symmetric extensions and show explicitly thesymmetric extension of isotropic states being the nearest to singlets in the setof symmetrically extendible states. The suitable regularization of the parameterprovides a new upper bound on one-way distillable entanglement.

Authors

• Marcin L Nowakowski,
• prof. dr hab. Paweł Horodecki link open in new tab