Hannover 2003 – wissenschaftliches Programm

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Q: Quantenoptik

Q 18: Quanteninformation 3

Q 18.1: Vortrag

Dienstag, 25. März 2003, 14:00–14:15, F102

Estimating the post-measurement state — •Thomas Konrad¹, Jürgen Audretsch¹, and Lajos Diósi² — ¹Fachbereich Physik Uni Konstanz — ²Research Institute for Particle and Nuclear Physics, Budapest, Hungary

We study generalized measurements (POVM measurements) on a single d-level quantum system which is in a completely unknown pure state and derive the best estimate of the post-measurement state. The mean post-measurement estimation fidelity is obtained and related to the operation fidelity of the device. This illustrates how the information gain about the post-measurement state and the corresponding state disturbance are mutually dependent. The connection between the best estimates of the pre- and post-measurement state is established and interpreted. For pure generalized measurements the two states coincide. The talk is based on e-print quant-ph/0210205