@article {2007,
	title = {Feedback stabilization of quantum ensembles: a global convergence analysis on complex flag manifolds},
	journal = {45th IEEE Conference on Decision and Control (2007) 2471-2476},
	number = {SISSA;65/2005/M},
	year = {2007},
	abstract = {In an N-level quantum mechanical system, the problem of unitary feedback stabilization of mixed density operators to periodic orbits admits a natural Lyapunov-based time-varying feedback design. A global description of the domain of attraction of the closed-loop system can be provided based on a \\\"root-space\\\"-like structure of the space of density operators. This convex set foliates as a complex flag manifold where each leaf is identified with the coadjoint orbit of the eigenvalues of the density operator. The converging conditions are time-independent but depend from the topology of the flag manifold: it is shown that the closed loop must have a number of equilibria at least equal to the Euler characteristic of the manifold, thus imposing obstructions of topological nature to global stabilizability.},
	doi = {10.1109/CDC.2006.377774},
	url = {http://hdl.handle.net/1963/1729},
	author = {Claudio Altafini}
}
