The control of quantum systems on the basis of continuous weak measurement has been developed along two main lines: so-called Markovian feedback, where the measurement output is just amplified and sent back as a drive to the system; and state-based feedback, where a full density operator is estimated with a quantum filter and well-behaved or optimal corrections are computed accordingly. In terms of controller complexity, these are two extreme cases. Markovian feedback has limited performance, a full filter can be computationally heavy even for moderate systems at ultra-fast timescales. We will report on our recent efforts to design controllers of intermediate complexity. In a first development, we introduce a low-dimensional dynamics to improve the performance of Markovian feedback. In a second development, we discuss a novel nonlinear structure in the quantum stochastic differential equation, which can enable to significantly reduce the dimension of the quantum filter.
De Florian Marquardt
De Gary Steele
De Hendrik Bluhm
De Jean-Michel Raimond
De Alain Sarlette
De Sylvain Schwartz
De Sophia Economou
De Klaus Mølmer
De Howard M. Wiseman
De Michel Devoret
De Akira Furusawa
De Yanhong Xiao
De Alex Retzker
De Nicolas Didier
De Ivan Deutsch
De Mankei Tsang
De Aashish Clerk
De Valentina Parigi
De Rebing Wu
De Michael Biercuk
De Thomas Ayral
De Nana Liu
De Nana Liu
