Closed-Loop and Robust Control of Quantum Systems

Table 1

Closed-loop and robust control approaches for quantum systems.

	Motivations	Typical methods	Applications
Closed-loop learning control	Direct the control results and procedures in an iteratively learning way	(1) Gradient-based methods; (2) Stochastic searching (GA); (3) RL methods	Controlling laboratory quantum phenomena with incomplete knowledge or unexpected uncertainties, for example, optimal laser control design.
Feedback control	Adjust control parameters according to instantaneous feedback information	(1) Lyapunov control; (2) Measurement-based control (3) Coherent-feedback control	Quantum state transition control, entanglement control, design of quantum gates, and so forth.
Robust control	Design control to achieve the best objective functional under the possible worst uncertainties	(1) 𝐻^∞ control; (2) Sliding mode control; (3) Risk-sensitive control; (4) Quantum ensemble control	Control design for quantum systems that are fragile and are subject to various kinds of uncertainties.