Hannover 2016 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 42: Poster: Quantum Optics and Photonics III

Q 42.14: Poster

Wednesday, March 2, 2016, 16:30–19:00, Empore Lichthof

Maximally entangled vs. separable: An approach to the characterization of random unitary channels — •Daniel Bruns, Jan Sperling, and Stefan Scheel — Insitut für Physik, Rostock

Modern applications in quantum computation and quantum communication necessitate the characterization of quantum states and quantum channels. In practice, this means that one has to determine the quantum performance of a physical system in terms of measurable quantities. Witnesses, if properly constructed, succeed in doing this task. We derive a method that is capable to construct witnesses for the characterization of channels, whose dynamics can be formulated solely in terms of a statistical mixture of unitary evolutions. Those random unitary channels were studied in [1] as giving evidence for classical error mechanisms occurring in the preparation and processing of quantum states.

It has been shown that random unitary channels are equivalent to bipartite quantum states decomposable into a convex combination of maximally entangled states. Conversely, a separable state is defined as a mixture of product states. Based on our treatment we are able to witness these opposing attributes at once and, furthermore, get an insight into the different geometric structures.

[1] K.M.R. Audenaert and S. Scheel. New J. Phys. 10, 023011 (2008)