Darmstadt 2008 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 28: Poster Quanteninformation

Q 28.1: Poster

Tuesday, March 11, 2008, 16:30–19:00, Poster C2

Adaptive Estimation of Qubits by Linear Optical Measurements — •Christof Happ and Matthias Freyberger — Institut für Quantenphysik, Universität Ulm, 89069 Ulm

Optical measurement methods for the estimation of an unknown qubit, of which only a limited number N of copies is available, are discussed. The studied methods compare a single copy of the unknown state |ψ⟩ to an arbitrary ruler state |r_ν⟩ by beam splitter measurements. Using Monte Carlo simulations, schemes for estimating |ψ⟩ as well as for adapting a reference state |r_ν⟩ for further measurements on remaining copies of |ψ⟩ were investigated. We present simulation results assessing the quality of estimation by the average fidelity |⟨ψ|ψ_N^est⟩|² between unknown and finally estimated state |ψ_N^est⟩.