Multiphonon anharmonic decay of a quantum mode

TL;DR

This paper introduces a nonperturbative theory for multiphonon anharmonic decay in quantum modes, revealing a critical level number where transition rates change abruptly, leading to burst-like energy loss and phonon emission in groups.

Contribution

It presents a novel nonperturbative framework for understanding multiphonon decay processes and predicts a critical level number affecting transition dynamics.

Findings

Transition rates slow down below the critical level number.

Transition rates accelerate above the critical level number.

Phonons are emitted in pairs, triplets, or larger groups depending on parameters.

Abstract

A nonperturbative theory of multiphonon anharmonic transitions between energy levels of a local mode is presented. It is shown that the rate of transitions rearranges near the critical level number $n_{cr}$: at smaller $n$ the process slows down, while at larger $n$ it accelerates in time, causing a jump-like loss of energy followed by the generation of phonon bursts. Depending on parameters, phonons are emitted in pairs, triplets etc.