  We theoretically analyze non-local electron transport in multi-terminal
normal-metal-superconductor-normal-metal (NSN) devices in the presence of an
external ac voltage bias. Our analysis reveals a number of interesting effects,
such as, e.g., photon-assisted violation of balance between crossed Andreev
reflection (CAR) and elastic cotunneling (EC). We demonstrate that at
sufficiently small (typically subgap) frequencies of an external ac signal and
at low temperatures the non-local conductance of the NSN device turns negative
implying that in this regime CAR contribution to the non-local current
dominates over that of EC. Our predictions can be directly tested in future
experiments.
