Spectrally resolved Overhauser shifts in single $\mathrm{GaAs}/{\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}$ As quantum dots

In this work, the direct observation of spectrally resolved, polarization-dependent shifts in excitonic Zeeman splittings arising from dynamic polarization of lattice nuclei (the Overhauser effect) in single quantum dots is reported. Overhauser shifts corresponding to effective nuclear fields greater than 1.3 T were observed from quantum dots in a 4.2-nm-wide quantum well. These electron-nuclear interactions are an important aspect of the optical properties of quantum dots and may significantly affect recombination dynamics in quantum dots even in the absence of an external magnetic field.