Phys.org August 26, 2022
Measurement and feedback control are essential features of quantum science, with applications ranging from quantum technology protocols to information-to-work conversion in quantum thermodynamics. Theoretical descriptions of feedback control are typically given in terms of stochastic equations requiring numerical solutions or are limited to linear feedback protocols. An international team of researchers (Sweden, USA – University of Maryland, Switzerland) presented a formalism for continuous quantum measurement and feedback, both linear and nonlinear. 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 fast measurements, they derived a Markovian master equation for the system alone, amenable to analytical treatment. They illustrated their formalism by investigating two basic information engines, one quantum and one classical…read more. Open Access TECHNICAL ARTICLE