Nuclear magnetic resonance spectroscopy of nonequilibrium steady states in quantum dots

TL;DR

This paper explores how nuclear magnetic resonance phenomena manifest in quantum dots under nonequilibrium conditions, revealing sharp NMR features in spin revival amplitudes influenced by nuclear composition.

Contribution

It demonstrates a new NMR spectroscopy method based on spin mode locking in quantum dots driven far from equilibrium.

Findings

Sharp NMR minima observed in revival amplitude dependence on magnetic field

Nuclear composition influences the nonequilibrium spin dynamics

Reveals a novel approach to NMR spectroscopy in quantum dots

Abstract

The optically induced polarization of localized electron spins in an ensemble of quantum dots (QDs) dephases due to the interaction with the surrounding nuclear spins. Despite this dephasing, the spins in the QDs can be controlled to respond coherently by applying periodic laser pulses, leading to a revival of the spin polarization before each pulse. This effect, known as spin mode locking, strongly depends on an emerging selection of certain polarizations of the nuclear spin bath which is driven to a steady state far from equilibrium. We investigate the influence of the nuclear composition in In$_x$Ga$_{1-x}$As QDs on this nonequilibrium behavior and demonstrate that nuclear magnetic resonances (NMR) appear as very sharp minima in the magnetic field dependence of the revival amplitude. This suggests a novel kind of NMR spectroscopy.