Year: 2008
Type: article
Abstract: We investigate quantum tunneling in a translation invariant chain of particles. The particles interact harmonically with their nearest neighbors except for one bond, which is anharmonic. It is described by a symmetric double-well potential. In the first step, we show how the anharmonic coordinate can be separated from the normal modes. This yields a Lagrangian which has been used to study quantum dissipation. Elimination of the normal modes leads to a nonlocal action of Caldeira-Leggett type. If the anharmonic bond defect is in the bulk, one arrives at Ohmic damping, i.e., there is a transition of a delocalized bond state to a localized one if the elastic constant exceeds a critical value ${C}_{\text{crit}}$. The latter depends on the masses of the bond defect. Super-Ohmic damping occurs if the bond defect is in the site $M$ at a finite distance from one of the chain ends. If the observation time $T$ is smaller than a characteristic time ${\ensuremath{\tau}}_{M}\ensuremath{\sim}M$, depending on the location $M$ of the defect, the behavior is similar to the bulk situation. However, for $T⪢{\ensuremath{\tau}}_{M}$ tunneling is never suppressed.
Source: Physical Review B
Authors: V. Fleurov, R. Schilling, B. Bayani
Institutions: Tel Aviv University, Johannes Gutenberg University Mainz
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funder: Israel Science Foundation
OpenAlex ID: W2054871442