Phase relaxation time tau(phi) due to Coulomb interactions is studied
semiclassically for electrons in open chaotic billiards with two leads
of width TY, When W is much larger than the Fermi wavelength lambda(F
), the phase relaxation time at temperature T is shown to be tau(phi)(
-1) = c(lambda(F)/W)T, where c is a numerical constant of the order of
unity. The behavior tau(phi) proportional to T-1, similar to that in
two-dimensional diffusive systems, is in agreement with the experiment
al results.