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Q: Quantenoptik und Photonik

Q 75: Poster Quanteninformation

Q 75.1: Poster

Thursday, March 16, 2006, 16:30–18:30, Labsaal

Adaptive quantum estimation of phase shifts — •Daniela Denot and Matthias Freyberger — Abteilung Quantenphysik, Universität Ulm, 89069 Ulm

We discuss an adaptive interferometric approach to quantum estimation of phase shifts. In a first step we find optimized two-mode input states for a generalized Mach-Zehnder interferometer. These two states show a small phase variance at the so-called Heisenberg limit. It turns out that they can be generated by entangling a coherent state and a squeezed vacuum at a beam splitter. Moreover, the interferometric setup allows us to describe an adaptive estimation scheme for arbitrary phase shifts if we assume a fixed mean photon number as a quantum resource. We minimize the error of this adaptive scheme for realistic squeezing parameters.