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Estimating the post-measurement state

Jürgen Audretsch·Lajos Diósi·Thomas Konrad
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Abstract

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-measuremement estimation fidelity of a generalized measurement 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.

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Jürgen Audretsch, Lajos Diósi, Thomas Konrad. 2002-10-30. Estimating the post-measurement state. https://doi.org/10.1103/physreva.68.034302

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