  The frictional forces in sheared fermionic gas are investigated. The gas is
sheared by two sliding surfaces. Except for a small imperfection (bulge) on one
of them, the surfaces are totally smooth. We show that when the bulge is
extremely small, and the gas is also confined in the lateral dimension, the
frictional force (F) is quantized. That is, F=m*mu*v, where v is the sliding
velocity with respect to the lubricant gas, m is an integer, and mu is the
friction coefficient. It is also shown that mu is proportional to the Planck
constant h and depends only on the bulge's properties (it does not depend on
either the gas properties or the sliding velocity).
