Yes, I understand how feedback control systems work. The question was whether they really have the fidelity to do it at hundred picometer resolution. I am dubi

Yes, I understand how feedback control systems work. The question was whether they really have the fidelity to do it at hundred picometer resolution. I am dubious because this is a pretty incredible feat. This is the length scale at which atom-atom interactions become important. That implies that the crystal lattice structure of both the read/write head and the underlying platter will affect the dynamics of the system!