MOMENTUM CONSERVATION IN MACROSCOPIC QUANTUM TUNNELING

This paper studies the effect of the momentum conservation on tunnelin g with dissipation. Two coupled macroscopic particles, interacting wit h a thermal bath of harmonic oscillators are considered. The interacti on between the particles is chosen such that it has minima at two diff erent separations. The exact effective action is obtained for the line ar coupling with the bath by the direct calculation of the imaginary-t ime path integral at arbitrary temperature, and by applying Leggett's prescription at T=0. The case of the Ohmic dissipation is studied in d etail. It is proved that the tunneling, at any strength of the dissipa tion, has a simple description in terms of the effective reduced mass that depends on temperature and classical friction coefficients. The c onnection with the Mossbauer effect is discussed.