The frictional drag force between quantum wells mediated by a fluctuating electromagnetic field

We use the theory of the fluctuating electromagnetic field to calculate the frictional drag force between nearby two- and three-dimensional electron systems. The frictional drag results from coupling via a fluctuating electromagnetic field, and can be considered as the dissipative part of the van der Waals interaction. Unlike in other similar calculations for semiconductor two-dimensional systems, here retardation effects are included. We consider the dependence of the frictional drag force on the temperature T, electron density and separation d. We find that retardation effects become the dominating factor for high electron densities n(s), corresponding to thin metallic film, for separation d > 10(epsilon /n(s))(1/2), where epsilon is the dielectric constant, and suggest a new experiment to test the theory. The relation between friction and heat transfer is also briefly commented on.