Berlin 2014 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 64: Quantum information: Concepts and methods V

Q 64.8: Talk

Friday, March 21, 2014, 15:45–16:00, Kinosaal

A universal set of qubit quantum channels — •Daniel Braun^1,2, Olivier Giraud³, Ion Nechita¹, Clément Pellegrini⁴, and Marko Znidaric⁵ — ¹Laboratoire de Physique Théorique, Université Paul Sabatier and CNRS, 31062 Toulouse, France — ²Institut für theoretische Physik, Universität Tübingen, 72076 Tübingen, Germany — ³LPTMS, UMR8626, Université Paris-Sud, CNRS, 91405 Orsay, France — ⁴Institut de Mathématiques de Toulouse, Université Paul Sabatier, 31062 Toulouse, France — ⁵Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia

We investigate the set of quantum channels acting on a single qubit. We provide a compact generalization of the Fujiwara-Algoet conditions for complete positivity to non-unital qubit channels, which we then use to characterize the possible geometric forms of the pure output of the channel. We provide universal sets of quantum channels for all unital qubit channels as well as for all extremal (not necessarily unital) qubit channels, in the sense that all qubit channels in these sets can be obtained by concatenation of channels in the corresponding universal set. We also show that our universal sets are essentially minimal.