106,187 research outputs found
Feedback Control of Quantum Transport
The current through nanostructures like quantum dots can be stabilized by a
feedback loop that continuously adjusts system parameters as a function of the
number of tunnelled particles . At large times, the feedback loop freezes
the fluctuations of which leads to highly accurate, continuous single
particle transfers. For the simplest case of feedback acting simultaneously on
all system parameters, we show how to reconstruct the original full counting
statistics from the frozen distribution.Comment: 4 pages, 2 figure
Feedback control of unsupported standing
This paper presents the results of continuing work on feedback control of unsupported standing in paraplegia. Our experimental setup considers a situation in which all joints above the ankle are braced, and stabilising torque at the ankle is generated by stimulation of the plantarflexors. A previous study showed that short periods of unsupported standing with paraplegic subjects could be achieved. In order to improve consistency and reliability of unsupported standing we are currently investigating several modifications to the control strategy. The paper reports progress towards this goal
Feedback control of spin systems
The feedback stabilization problem for ensembles of coupled spin 1/2 systems
is discussed from a control theoretic perspective. The noninvasive nature of
the bulk measurement allows for a fully unitary and deterministic closed loop.
The Lyapunov-based feedback design presented does not require spins that are
selectively addressable. With this method, it is possible to obtain control
inputs also for difficult tasks, like suppressing undesired couplings in
identical spin systems.Comment: 16 pages, 15 figure
Towards feedback control of entanglement
We provide a model to investigate feedback control of entanglement. It
consists of two distant (two-level) atoms which interact through a radiation
field and becomes entangled. We then show the possibility to stabilize such
entanglement against atomic decay by means of a feedback action.Comment: 6 pages, 4 figure
Thermodynamics of adiabatic feedback control
We study adaptive control of classical ergodic Hamiltonian systems, where the
controlling parameter varies slowly in time and is influenced by system's state
(feedback). An effective adiabatic description is obtained for slow variables
of the system. A general limit on the feedback induced negative entropy
production is uncovered. It relates the quickest negentropy production to
fluctuations of the control Hamiltonian. The method deals efficiently with the
entropy-information trade off.Comment: 6 pages, 1 figur
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