Hydrodynamic theory of photon drag

We derive and evaluate a hydrodynamic theory of photon-drag effects in simple metals. Considering a jellium surface obliquely illuminated by monochromatic light, we calculate both the steady surface-parallel current and the emf induced along the surface normal. The sizes of these effects are estimated with a variety of approaches, ranging from momentum-balance arguments, through sum rules, to detailed microscopic calculations using a hydrodynamic description of the electrons' dynamics. Comparisons between the sometimes different results help clarify the physical origin of the phenomena, in particular, the extent to which effects are surface sensitive. We also outline a calculational approach that should allow a tractable incorporation of quantum-mechanical dynamics.