Momentum conservation in macroscopic quantum tunneling

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Abstract
This paper studies the effect of the momentum conservation on tunneling with dissipation. Two coupled macroscopic particles, interacting with a thermal bath of harmonic oscillators are considered. The interaction between the particles is chosen such that it has minima at two different separations. The exact effective action is obtained for the linear coupling with the bath by the direct calculation of the imaginary-time path integral at arbitrary temperature, and by applying Leggett’s prescription at T=0. The case of the Ohmic dissipation is studied in detail. It is proved that the tunneling, at any strength of the dissipation, has a simple description in terms of the effective reduced mass that depends on temperature and classical friction coefficients. The connection with the Mössbauer effect is discussed. © 1996 The American Physical Society.