A General Formalism for Continuous Feedback Control in Quantum Systems

Author: Björn Annby-andersson; Nanolund: Center For Nanoscience; []

Keywords: NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; TEKNIK OCH TEKNOLOGIER; NATURAL SCIENCES; ENGINEERING AND TECHNOLOGY; quantum measurements; quantum control; stochastic thermodynamics; information thermodynamics; full count- ing statistics; open quantum systems; Quantum measurements; Quantum control; Stochastic thermodynamics; Information thermodynamics; Full counting statistics; Open quantum systems;

Abstract: This thesis devolops a general formalism for continuous feedback control in quantum systems. The main result is a quantum Fokker-Planck master equation describing the joint dynamics of a quantum system and a detector with finite bandwidth. For a fast detector, this equation can be reduced to a Markovian master equation for the system dynamics. In particular, the formalism is amenable to analytical treatments of feedback protocols that depend nonlinearly on the measured signal. Previously, only numerical methods were available for this. We apply the formalism on two toy models to highlight its usefuleness. We find that the formalism provides insight into the connection between thermodynamics and information theory.

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