Hannover 2003 – scientific programme

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Q: Quantenoptik

Q 18: Quanteninformation 3

Q 18.2: Talk

Tuesday, March 25, 2003, 14:15–14:30, F102

A group theoretical approach to quantum state estimation — •Michael Keyl — Inst. Math. Phys., TU-Braunschweig

In [M. Keyl, R. F. Werner, PRA 64 (2001) 052311] a measurement scheme was proposed, which operates on N systems, all prepared according to the same density operator ρ, and which approximately yields the spectrum of ρ. In this talk we show how this scheme can be generalized to get an estimation strategy for the full density matrix. The construction is (as the original proposal) based on representation theory of unitary and symmetric groups. We analyze the large deviation behaviour of the estimators (i.e. the decay of error probabilities as N → ∞) and ask whether (and in which sense) the scheme is optimal.