Phonon-induced relaxation of a two-state system in solids

TL;DR

This paper analyzes how phonons cause relaxation in a two-state quantum system within solids, deriving measurable expressions for relaxation rates and highlighting the dominance of two-phonon processes at elevated temperatures.

Contribution

It provides a theoretical framework for calculating phonon-induced relaxation rates in two-state systems, incorporating symmetry and bias effects, and emphasizes the role of two-phonon processes.

Findings

Two-phonon processes dominate relaxation at higher temperatures.

Relaxation rates can be expressed using measurable parameters due to symmetry.

Bias controls the relaxation rate via parity effects.

Abstract

We study phonon-induced relaxation of quantum states of a particle (e.g., electron or proton) in a rigid double-well potential in a solid. Relaxation rate due to Raman two-phonon processes have been computed. We show that in a two-state limit, symmetry arguments allow one to express these rates in terms of independently measurable parameters. In general, the two-phonon processes dominate relaxation at higher temperature. Due to parity effect in a biased two-state system, their rate can be controlled by the bias.