Nonequilibrium nuclear-electron spin dynamics in semiconductor quantum dots

TL;DR

This study investigates the nonequilibrium spin dynamics of electrons and nuclei in semiconductor quantum dots, revealing nearly complete nuclear polarization at high temperatures and a distinct polarization mode from bulk semiconductors.

Contribution

It provides direct time-resolved observations of nuclear polarization formation and decay in quantum dots, highlighting a nonequilibrium polarization mode not described by traditional spin temperature models.

Findings

Achieved almost complete nuclear polarization at elevated temperatures.

Resolved the formation and decay of dynamical nuclear polarization in real time.

Identified a nonequilibrium nuclear polarization mode different from bulk semiconductor models.

Abstract

We study the spin dynamics in charged quantum dots in the situation where the resident electron is coupled to only about 200 nuclear spins and where the electron spin splitting induced by the Overhauser field does not exceed markedly the spectral broadening. The formation of a dynamical nuclear polarization as well as its subsequent decay by the dipole-dipole interaction is directly resolved in time. Because not limited by intrinsic nonlinearities, almost complete nuclear polarization is achieved, even at elevated temperatures. The data suggest a nonequilibrium mode of nuclear polarization, distinctly different from the spin temperature concept exploited on bulk semiconductors