The Fisher information and the quantum Cramer-Rao sensitivity limit of continuous measurements

2013/10/31 by Søren Gammelmark, Klaus Mølmer · 4 citations
Physics and Astronomy · #quant-ph

paper · pdf · doi:10.1103/physrevlett.112.170401

published as Phys. Rev. Lett. 112, 170401 (2014) · 5 pages, 2 figures. Published version, significantly revised. Supplemental Information available upon request to the second author

arxiv created 2014/05/02 · arxiv updated 2015/06/17

Abstract

Precision measurements with quantum systems rely on our ability to trace the differences between experimental signals to variations in unknown physical parameters. In this Letter we derive the Fisher information and the ensuing Cramer-Rao sensitivity limit for parameter estimation by continuous measurements on an open quantum system. We illustrate our theory by application to resonance fluorescence from a laser driven two-state atom and we show that photon counting and homodyne detection records yield different sensitivity to the atomic parameters, while none of them exceed our general result.

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