Stuttgart 2012 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 2: Quanteninformation: Konzepte und Methoden 1
Q 2.7: Talk
Monday, March 12, 2012, 12:00–12:15, V7.03
Accessible nonlinear entanglement witnesses. — •Oleg Gittsovich1,2, Juan Miguel Arrazola1,2, and Norbert Lütkenhaus1,2 — 1Institute for Quantum Computing, University of Waterloo, 200 University Avenue West, N2L 3G1 Waterloo, Ontario, Canada — 2Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, N2L 3G1 Waterloo, Ontario, Canada
Deciding whether a given quantum state is entangled or not is a difficult task. In a vast majority of experiments entanglement witnesses are used in order to prove presence of entanglement. Entanglement witnesses can be constructed from available measurement results and do not require reconstruction of the whole density matrix (full tomography). We provide a method to construct accessible nonlinear entanglement witnesses, which incorporate two important properties. First, they improve linear entanglement witnesses and as a result detect more entangled states with high statistical significance. Second, we can go from evaluating linear entanglement witnesses to their nonlinear counterpart without additional experimental effort, which makes them attractive for implementations in current experiments.