We study to what extent the detrimental impact of dissipation on quantum
properties can be compensated by suitable coherent dynamics. To this end, we
develop a general method to determine the control Hamiltonian that optimally
counteracts a given dissipation mechanism, in order to sustain the desired
property, and apply it to two exemplary target properties: the coherence of a
decaying two-level system, and the entanglement of two qubits in the presence
of local dissipation.Comment: 6 pages. Corresponds to published versio
