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Open AccessJournal ArticleDOI

Bellman equations for optimal feedback control of qubit states

Luc Bouten, +2 more
- 24 Jan 2005 - 
- Vol. 38, Iss: 3, pp 151-160
TLDR
In this article, an optimal control strategy for an open two-level system (a qubit in interaction with the electromagnetic field) controlled by a laser is derived using results from quantum filtering theory and methods from classical control theory.
Abstract
Using results from quantum filtering theory and methods from classical control theory, we derive an optimal control strategy for an open two-level system (a qubit in interaction with the electromagnetic field) controlled by a laser. The aim is to optimally choose the laser's amplitude and phase in order to drive the system into a desired state. The Bellman equations are obtained for the case of diffusive and counting measurements for vacuum field states. A full exact solution of the optimal control problem is given for a system with simpler, linear, dynamics. These linear dynamics can be obtained physically by considering a two-level atom in a strongly driven, heavily damped, optical cavity.

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Citations
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Journal ArticleDOI

An Introduction to Quantum Filtering

TL;DR: In this paper, an introduction to quantum probability theory is given, focusing on the spectral theorem and the conditional expectation as a least squares estimate, and culminating in the construction of Wiener and Poisson processes on the Fock space.
Journal ArticleDOI

A Discrete Invitation to Quantum Filtering and Feedback Control

TL;DR: This expository paper demonstrates estimation and feedback control of quantum mechanical systems in what is essentially a noncommutative version of the binomial model that is popular in mathematical finance and allows a full development of the theory while remaining completely within the setting of finite-dimensional Hilbert spaces.
Posted Content

Optimal Quantum Filtering and Quantum Feedback Control

TL;DR: In this article, a quantum Bellman equation is applied to the explicitly solvable quantum linear-quadratic-Gaussian (LQG) problem, which emphasizes many similarities with the corresponding classical control problem.
Journal ArticleDOI

Quantum games: a review of the history, current state, and interpretation

TL;DR: This work reviews both theoretical and experimental developments in the area of quantum games since the inception of the subject circa 1999 and offers a narrative on the controversy that surrounded the subject in its early days.
References
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Dynamic Programming

TL;DR: The more the authors study the information processing aspects of the mind, the more perplexed and impressed they become, and it will be a very long time before they understand these processes sufficiently to reproduce them.
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TL;DR: In this article, the memory effects in a quantum-mechanical master equation become negligible in the weak coupling limit for a finite-dimensional system weakly coupled to an infinite free heat bath.
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Journal ArticleDOI

Quantum feedback control and classical control theory

TL;DR: In this paper, the authors introduce and discuss the problem of quantum feedback control in the context of established formulations of classical control theory, examining conceptual analogies and essential differences, and apply their methods to the particular case of switching the state of a particle in a double-well potential.
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