Ultrafast spectroscopies constitute a fundamental tool to investigate the
dynamics of non-equilibrium many-body states in correlated materials.
Two-pulses (pump-probe) experiments have shed new light on the interplay
between high-energy electronic excitations and the emerging low-energy
properties, such as superconductivity and charge-order, in many interesting
materials. Here we will review some recent results on copper oxides and we will
propose the use of high-resolution multi-dimensional techniques to investigate
the decoherence processes of optical excitations in these systems. This novel
piece of information is expected to open a new route toward the understanding
of the fundamental interactions that lead to the exotic electronic and magnetic
properties of correlated materials.Comment: Invited by S.I.F. To appear in Nuovo Cimento C. 7 pages, 4 figure
