The effects of decoherence on Fermi's golden rule

TL;DR

This paper investigates how decoherence influences Fermi's golden rule in quantum systems, revealing significant deviations when decoherence times are short, using non-adiabatic molecular dynamics and first-principles calculations on monolayer WS2.

Contribution

It introduces a study of decoherence effects on Fermi's golden rule using non-adiabatic molecular dynamics and applies it to monolayer WS2 with first-principles methods.

Findings

Decoherence causes significant deviations from Fermi's golden rule at short decoherence times.

The effect is analyzed in both fixed and adiabatic bases.

First-principles calculations on WS2 illustrate the impact of electron-phonon coupling.

Abstract

Fermi's golden rule which describes the transition rates between two electronic levels under external stimulations is used ubiquitously in different fields of physics. The original Fermi's golden rule was derived from perturbative time-dependent Schr\"{o}dinger's equation without the direct contribution by decoherence effect. However, as a result of recent developments of quantum computing and ultra fast carrier dynamics, the decoherence becomes a prominent topic in fundamental research.Here, by using the non-adiabatic molecular dynamics which goes beyond the time-dependent Schr\"{o}dinger's equation by introducing decoherence, we study the effect of decoherence on Fermi's golden rule for the fixed basis and the adiabatic basis, respectively. We find that when the decoherence time becomes short, there is a significant deviation from the Fermi's golden rule for both bases. By using monolayer $\mathrm{WS_2}$ as an example, we investigate the decoherence effect in the carrier transitions induced by the electron-phonon coupling with first-principle method.