  The Ponderomotive force is a static second order force that a particle feels
in an oscillating field, whose static potential may be called the Ponderomotive
potential. We generalize this notion to that for generic degrees of freedom in
periodically driven quantum many-body systems, and propose it as a convenient
tool to engineer the non-equilibrium steady states beyond the single particle
level. Applied to materials driven by light, the Ponderomotive potential is
intimately related to the optical conductivity, which is enhanced close to
resonances. We show that the Ponderomotive potential from the incident light
may be used to induce exciton condensates in semiconductors, to generate
attractive interactions leading to superconductivity in certain electron-phonon
systems, and to create additional free energy minima in systems with
charge/spin/excitonic orders. These effects are shown for realistic parameters
such that they can be readily verified in ultrafast experiments.
