  The theory of the drag effects in the system of spatially separated electrons
and excitons in coupled quantum wells (QW) embedded in an optical microcavity
is developed. It is shown that at low temperature an electron current induces
the (normal component) polariton flow, therefore, a transport of photons along
the cavity. However, the electron current dragged by the polariton flow is
strongly suppressed below polariton superfluid transition temperature and
hence, the strong suppression of the induced electron current indicates the
superfluidity of polaritons. Therefore, the transport properties of polaritons
can be investigated by measuring the current or voltage in the electron
subsystem. At high temperatures we study the exciton-electron drag effects. At
high temperatures regime, from one hand, the existence of the electric current
in an electron QW induces the exciton flow in the other QW, from the other
hand, the electron current in one QW induces the exciton flow in the other QW
via the drag of excitons by the electrons. The drag coefficients for the
polariton-electron systems are calculated and analyzed. We discuss the possible
experimental observation of the drag effects in the system of electrons and
microcavity polaritons, that also allow to observe the cavity polaritons
superfluidity.
