Feedback Control of Nonlinear Quantum Systems: A Rule of Thumb
Kurt A. Jacobs, Austin P. Lund · Physical Review Letters · 2007
We show that in the regime in which feedback control is most effective - when measurements are relatively efficient, and feedback is relatively strong - then, in the absence of any sharp inhomogeneity in the noise, it is always best to measure in a basis that does not commute with the system density matrix than one that does. That is, it is optimal to make measurements that disturb the state one is attempting to stabilize.