Dynamics and relaxation of sp biexcitons in disk-shaped quantum dots

TL;DR

This paper investigates how intraband relaxation affects the optical control of sp biexcitons in CdTe disk-shaped quantum dots, highlighting the stability of certain triplet states against decoherence.

Contribution

It provides a detailed analysis of the dynamics and relaxation processes of sp biexcitons, including the impact of correlation effects and transient state structures.

Findings

Fast hole relaxation limits high-fidelity operations.

Triplet states are more stable against decoherence.

Transient states involve two holes on the s shell and antiparallel sp triplet electrons.

Abstract

We study the effects of intraband relaxation processes on optical manipulation protocols for sp biexcitons hosted by CdTe disk-shaped quantum dots. The many-body states are calculated within the configuration interaction method starting from single-particle states given by the kp theory. The time-dependent occupations of relevant many-body states are extracted from the von Neumann-Lindblad equation for the density operator. We mainly investigate the generation of sp biexcitons with two pulses of different polarizations sigma_{+} and sigma_{-}. The fast hole relaxation processes prevent a high-fidelity controlled operation on sp biexcitons and lead to the occupation of some transient states which can be optically probed. More importantly, the many-body structure of the transient states consists of two holes on the $s$ shell and antiparallel sp triplet states for electrons. Our simulations show that these triplet states are more stable against decoherence as they can only be damaged through slow electron relaxation. The configuration mixing due to correlation effects is also discussed.