Functorial relationships between quantum cohomology of complete and partial flag varieties

We give a natural filtration F on quantum cohomology QH(G/B) of G/B, which respects the quantum product structure. Its associated graded algebra is isomorphic to the tensor product of QH(G/P) and a corresponding graded algebra of QH(P/B) after localization. When the quantum parameter goes to zero, this specializes to the filtration on the classical cohomology H(G/B) from the Leray spectral sequence associated to the fibration P/B --> G/B --> G/P.