Comment on "Are There Traps in Quantum Control Landscapes?"
  Many quantum control problems are formulated as a search for an optimal field that maximizes a physical objective. This search is performed over a landscape defined as the objective as a function of the control field. A recent Letter [A. N. Pechen and D. J. Tannor, Phys. Rev. Lett. 106, 120402 (2011)] asserts that the existence of special landscape critical points (CPs) with trapping characteristics is "contrary to recent claims in the literature" and "can have profound implications for both theoretical and experimental quantum control studies." We show here that these assertions are inaccurate and misleading. 
Herschel Rabitz, Tak-San Ho, Ruixing Long, Rebing Wu, Constantin Brif
quant-ph physics.chem-ph