Locally Optimal Control of Quantum Systems with Strong Feedback
arXiv:0803.2705 · doi:10.1103/PhysRevLett.101.230403
Abstract
For quantum systems with high purity, we find all observables that, when continuously monitored, maximize the instantaneous reduction in the von Neumann entropy. This allows us to obtain all locally optimal feedback protocols with strong feedback, and explicit expressions for the best such protocols for systems of size N <= 4. We also show that for a qutrit the locally optimal protocol is the optimal protocol for a given range of control times, and derive an upper bound on all optimal protocols with strong feedback.
4 pages, Revtex4. v2: published version (some errors corrected)
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- Continuous Measurement of a Non-Markovian Open Quantum System
- Deterministic creation and stabilization of entanglement in circuit QED by homodyne-mediated feedback control
- Rapid purification of quantum systems by measuring in a feedback-controlled unbiased basis
- Monitoring the wave function by time continuous position measurement
- Extended Techniques for Feedback Control of A Single Qubit
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- Maximum information gain in weak or continuous measurements of qudits: complementarity is not enough
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- Optimality of qubit purification protocols in the presence of imperfections
- Discrete-Time Controllability for Feedback Quantum Dynamics
- Restoring metrological quantum advantage of measurement precision in noisy scenario
- Global versus local optimality in feedback-controlled qubit purification: new insights from minimizing Rényi entropies
- Optimal measurement-based feedback control for a single qubit: a candidate protocol
- Quantum feedback for measurement and control