Erlangen 2018 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 15: Quantum Information (Concepts and Methods) II
Q 15.4: Vortrag
Montag, 5. März 2018, 15:00–15:15, K 1.019
Information Disturbance Tradeoff in Quantum Measurement — Lukas Knips1,2, •Jan Dziewior1,2, Anna-Lena Hashagen3, Jasmin Meinecke1,2, Michael Wolf3, and Harald Weinfurter1,2 — 1Department for Physics, LMU, 80797 Munich — 2Max-Planck-Institute for Quantum Optics, 85748 Garching — 3Zentrum Mathematik, TUM, 85748 Garching
One of the most characteristic features of quantum mechanics is that every measurement which extracts information from a physical system necessarily causes an irreducible disturbance. While this fundamental complementarity has been considered in numerous works, recently an analysis of unprecedented generality has been performed [1]. In particular it provides a dimension-independent optimal tradeoff relation for general von Neumann measurements based on the cb-norm for quantum channels as a distance measure. We evaluate this relation experimentally for the observation of a qubit by implementing the full range of possible measurements and determining the amount of accessible information for a given disturbance. The various measurements are realized by a tunable Mach-Zehnder-Interferometer, which supplies the ancillary degrees of freedom necessary to implement arbitrary POVMs and quantum channels for the measurement of a polarization qubit. Not only are we able to show the validity of the fundamental bound, but, furthermore, achieve the demonstration of its tightness by saturating it with high significance.
[1] Hashagen, A., Wolf, M., Universality and Optimality in the Information-Disturbance Tradeoff, in preparation.