735 research outputs found
Feedback control of probability amplitudes for two-level atom in optical field
We demonstrate the possibility to stabilize the probability amplitude of the
upper level for a single quantum two-level atom in a classical optical field
with feedback control scheme.Comment: 7 pages, 3 figure
Adaptive Tuning of Feedback Gain in Time-Delayed Feedback Control
We demonstrate that time-delayed feedback control can be improved by
adaptively tuning the feedback gain. This adaptive controller is applied to the
stabilization of an unstable fixed point and an unstable periodic orbit
embedded in a chaotic attractor. The adaptation algorithm is constructed using
the speed-gradient method of control theory. Our computer simulations show that
the adaptation algorithm can find an appropriate value of the feedback gain for
single and multiple delays. Furthermore, we show that our method is robust to
noise and different initial conditions.Comment: 7 pages, 6 figure
Adaptive synchronization in delay-coupled networks of Stuart-Landau oscillators
We consider networks of delay-coupled Stuart-Landau oscillators. In these
systems, the coupling phase has been found to be a crucial control parameter.
By proper choice of this parameter one can switch between different synchronous
oscillatory states of the network. Applying the speed-gradient method, we
derive an adaptive algorithm for an automatic adjustment of the coupling phase
such that a desired state can be selected from an otherwise multistable regime.
We propose goal functions based on both the difference of the oscillators and a
generalized order parameter and demonstrate that the speed-gradient method
allows one to find appropriate coupling phases with which different states of
synchronization, e.g., in-phase oscillation, splay or various cluster states,
can be selected.Comment: 8 pages, 7 figure
Chaotic Observer-based Synchronization Under Information Constraints
Limit possibilities of observer-based synchronization systems under
information constraints (limited information capacity of the coupling channel)
are evaluated. We give theoretical analysis for multi-dimensional
drive-response systems represented in the Lurie form (linear part plus
nonlinearity depending only on measurable outputs). It is shown that the upper
bound of the limit synchronization error (LSE) is proportional to the upper
bound of the transmission error. As a consequence, the upper and lower bounds
of LSE are proportional to the maximum rate of the coupling signal and
inversely proportional to the information transmission rate (channel capacity).
Optimality of the binary coding for coders with one-step memory is established.
The results are applied to synchronization of two chaotic Chua systems coupled
via a channel with limited capacity.Comment: 7 pages, 6 figures, 27 reference
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