The regime of good control

2009 ◽  
Vol 9 (5&6) ◽  
pp. 395-405
Author(s):  
J. Li ◽  
K. Jacobs
Keyword(s):  
Steady State ◽  
Feedback Control ◽  
Nonlinear Systems ◽  
Equations Of Motion ◽  
Good Control ◽  
Classical Case ◽  
Quantum Systems ◽  
Single Qubit ◽  
Control Of Quantum Systems ◽  
Steady State Performance

We derive the equations of motion describing the feedback control of quantum systems in the regime of ``good control", in which the control is sufficient to keep the system close to the desired state. One can view this regime as the quantum equivalent of the ``linearized" regime for feedback control of classical nonlinear systems. Strikingly, while the dynamics of a single qubit in this regime is indeed linear, that of all larger systems remains nonlinear, in contrast to the classical case. As a first application of these equations, we determine the steady-state performance of feedback protocols for a single qubit that use unbiased measurements.

scholarly journals Experimental Feedback Control of Quantum Systems Using Weak Measurements

2010 ◽  
Vol 104 (8) ◽  
Author(s):  
G. G. Gillett ◽  
R. B. Dalton ◽  
B. P. Lanyon ◽  
M. P. Almeida ◽  
M. Barbieri ◽  
...  
Keyword(s):  
Feedback Control ◽  
Quantum Systems ◽  
Weak Measurements ◽  
Control Of Quantum Systems

scholarly journals Closed-Loop and Robust Control of Quantum Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Chunlin Chen ◽  
Lin-Cheng Wang ◽  
Yuanlong Wang
Keyword(s):  
Robust Control ◽  
Feedback Control ◽  
Quantum Control ◽  
Closed Loop ◽  
Learning Control ◽  
Quantum Systems ◽  
General Idea ◽  
Control Measurement ◽  
Control Of Quantum Systems ◽  
Control Feedback

For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control asH∞control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.

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