Relaxation properties of the quantum kinetics of carrier-LO-phonon interaction in quantum wells and quantum dots

TL;DR

This paper investigates the relaxation dynamics of optically excited carriers in quantum wells and dots interacting with LO-phonons, comparing full two-time Green's function formalism with a one-time approximation, revealing differences in thermalization behavior.

Contribution

It provides a comparative analysis of two quantum kinetic approaches, highlighting the importance of two-time formalism for accurate thermalization description.

Findings

Two-time quantum kinetics achieves thermalization in all cases.

One-time approximation fails to produce thermalization in intermediate coupling.

Full formalism aligns with the Kubo-Martin-Schwinger thermalization criterion.

Abstract

The time evolution of optically excited carriers in semiconductor quantum wells and quantum dots is analyzed for their interaction with LO-phonons. Both the full two-time Green's function formalism and the one-time approximation provided by the generalized Kadanoff-Baym ansatz are considered, in order to compare their description of relaxation processes. It is shown that the two-time quantum kinetics leads to thermalization in all the examined cases, which is not the case for the one-time approach in the intermediate-coupling regime, even though it provides convergence to a steady state. The thermalization criterion used is the Kubo-Martin-Schwinger condition.