Shearing a fermionic gas and quantized friction
  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). 
Er'el Granot