Bayesian feedback versus Markovian feedback in a two-level atom

Wiseman, H. M., Mancini, S. and Wang, J. (2002) Bayesian feedback versus Markovian feedback in a two-level atom. Physical Review A, 66 1: 013807. doi:10.1103/PhysRevA.66.013807

Author Wiseman, H. M.
Mancini, S.
Wang, J.
Title Bayesian feedback versus Markovian feedback in a two-level atom
Journal name Physical Review A   Check publisher's open access policy
ISSN 1050-2947
Publication date 2002
Sub-type Article (original research)
DOI 10.1103/PhysRevA.66.013807
Volume 66
Issue 1
Start page 013807
Total pages 9
Editor B. Crasemann
Place of publication United States
Publisher American Physical Society
Collection year 2002
Language eng
Subject C1
240201 Theoretical Physics
780102 Physical sciences
Abstract We compare two different approaches to the control of the dynamics of a continuously monitored open quantum system. The first is Markovian feedback, as introduced in quantum optics by Wiseman and Milburn [Phys. Rev. Lett. 70, 548 (1993)]. The second is feedback based on an estimate of the system state, developed recently by Doherty and Jacobs [Phys. Rev. A 60, 2700 (1999)]. Here we choose to call it, for brevity, Bayesian feedback. For systems with nonlinear dynamics, we expect these two methods of feedback control to give markedly different results. The simplest possible nonlinear system is a driven and damped two-level atom, so we choose this as our model system. The monitoring is taken to be homodyne detection of the atomic fluorescence, and the control is by modulating the driving. The aim of the feedback in both cases is to stabilize the internal state of the atom as close as possible to an arbitrarily chosen pure state, in the presence of inefficient detection and other forms of decoherence. Our results (obtained without recourse to stochastic simulations) prove that Bayesian feedback is never inferior, and is usually superior, to Markovian feedback. However, it would be far more difficult to implement than Markovian feedback and it loses its superiority when obvious simplifying approximations are made. It is thus not clear which form of feedback would be better in the face of inevitable experimental imperfections.
Keyword Optics
Physics, Atomic, Molecular & Chemical
Stochastic Differential-equations
Quantum Feedback
Homodyne Detection
Optical Feedback
2-level Atom
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Mathematics and Physics
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