טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAlmog Danzig
SubjectObservation of quantum (phonon) friction in hcp solid
4He
DepartmentDepartment of Physics
Supervisor Professor Emeritus Polturak Emil
Full Thesis textFull thesis text - English Version


Abstract

Quantum friction is a dissipative force resulting from exchange of quantized excitations between solid bodies moving relative to each other. One such quantum mechanism of friction involving phonons was predicted by Popov.  Here, we present measurements of the friction force between crystallites of solid 4He contained inside a torsional oscillator. Our data are in excellent agreement with the temperature dependence predicted by the phonon friction model. This quantum friction force is many orders of magnitude weaker than classical friction at room temperature. To the best of our knowledge this is the first experimental observation of quantum friction.