138,160 research outputs found
Understanding ACT-R - an Outsider's Perspective
The ACT-R theory of cognition developed by John Anderson and colleagues
endeavors to explain how humans recall chunks of information and how they solve
problems. ACT-R also serves as a theoretical basis for "cognitive tutors",
i.e., automatic tutoring systems that help students learn mathematics, computer
programming, and other subjects. The official ACT-R definition is distributed
across a large body of literature spanning many articles and monographs, and
hence it is difficult for an "outsider" to learn the most important aspects of
the theory. This paper aims to provide a tutorial to the core components of the
ACT-R theory
Maximizing information on the environment by dynamically controlled qubit probes
We explore the ability of a qubit probe to characterize unknown parameters of
its environment. By resorting to quantum estimation theory, we analytically
find the ultimate bound on the precision of estimating key parameters of a
broad class of ubiquitous environmental noises ("baths") which the qubit may
probe. These include the probe-bath coupling strength, the correlation time of
generic bath spectra, the power laws governing these spectra, as well as their
dephasing times T2. Our central result is that by optimizing the dynamical
control on the probe under realistic constraints one may attain the maximal
accuracy bound on the estimation of these parameters by the least number of
measurements possible. Applications of this protocol that combines dynamical
control and estimation theory tools to quantum sensing are illustrated for a
nitrogen-vacancy center in diamond used as a probe.Comment: 8 pages + 6 pages (appendix), 3 Figure
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