State and dynamical parameter estimation for open quantum systems

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Title State and dynamical parameter estimation for open quantum systems
Author Gambetta, Jay; Wiseman, Howard Mark
Journal Name Physical Review A: Atomic, Molecular and Optical Physics
Editor Bernd Crasemann
Year Published 2001
Place of publication USA
Publisher American Physical Society
Abstract Following evolution of an open quantum system one requires full knowledge of its dynamics. In this paper we consider open quantum systems for which the Hamiltonian is “uncertain.” In particular, we treat in detail a simple system similar to that considered by Mabuchi [Quant. Semiclass. Opt. 8, 1103 (1996)]: a radiatively damped atom driven by an unknown Rabi frequency Ω (as would occur for an atom at an unknown point in a standing light wave). By measuring the environment of the system, knowledge about the system state, and about the uncertain dynamical parameter, can be acquired. We find that these two sorts of knowledge acquisition (quantified by the posterior distribution for Ω, and the conditional purity of the system, respectively) are quite distinct processes, which are not strongly correlated. Also, the quality and quantity of knowledge gain depend strongly on the type of monitoring scheme. We compare five different detection schemes (direct, adaptive, homodyne of the x quadrature, homodyne of the y quadrature, and heterodyne) using four different measures of the knowledge gain (Shannon information about Ω, variance in Ω, long-time system purity, and short-time system purity).
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Copyright Statement Copyright 2001 American Physical Society. Reproduced in accordance with the copyright policy of the publisher. This journal is available online - use hypertext links.
Volume 64
Issue Number 4
Page from 042105.1
Page to 042105.14
ISSN 1050-2947
Date Accessioned 2002-04-15
Language en_AU
Research Centre Centre for Quantum Dynamics
Faculty Faculty of Science
Subject PRE2009-Theoretical Physics
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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