Hannover 2010 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 44: Quantum Information: Concepts and Methods III
Q 44.4: Vortrag
Donnerstag, 11. März 2010, 11:15–11:30, E 214
Quantifying entanglement from scattering data — •Harald Wunderlich1,2,3, Marcus Cramer1,2,3, and Martin B. Plenio1,2,3 — 1Institut für Theoretische Physik, Universität Ulm, Germany — 2Institute for Mathematical Sciences, Imperial College London, United Kingdom — 3QOLS, Blackett Laboratory, Imperial College London, United Kingdom
We demonstrate that the quantification of entanglement from scattering data according to an entanglement measure of choice (such as the robustness of entanglement or the best separable approximation) can be performed via a direct minimization of the entanglement over all states compatible with the measurement data. This can be achieved numerically employing methods from the theory of semidefinite programming.
Taking into account the symmetries allowed by the observables, the optimization may be restricted to states obeying the same symmetries. In order to illustrate the power of our method we apply this estimation method to thermal Heisenberg states.
Since for large quantum systems numerical calculations become intractable, we show how to obtain analytical lower bounds to entanglement measures via witness operators based on uncertainty relations.