Nuclear spin polarization in a single quantum dot pumped by two laser beams

TL;DR

This paper theoretically explores how two laser beams can induce and control nuclear spin polarization in a single quantum dot, revealing conditions for weak and strong polarization and their effects on nuclear spin distribution.

Contribution

It introduces a theoretical model for nuclear spin polarization driven by dual laser pumping in quantum dots, highlighting the potential for both weak and strong polarization regimes.

Findings

Weak nuclear spin polarization narrows the Overhauser field distribution.

Strong polarization can be achieved with suitable laser parameters.

Theoretical predictions align with Monte Carlo simulation results.

Abstract

We theoretically investigate dynamic nuclear spin polarization in a self-assembled quantum dot pumped optically by two laser beams. With the assumption that a noncollinear interaction between the hole spin and nuclear spins leads to nuclear spin polarization, we find that both weak and strong nuclear spin polarizations can arise, depending on the intensities and central frequencies of the lasers. For weak nuclear spin polarization, we use a perturbation method to show that the distribution of the nuclear spin Overhauser field may become significantly narrower. Using Monte Carlo simulations to study a single quantum dot, we find that strong nuclear spin polarization can also be generated via appropriate optical pumping.