Confluence of resonant laser excitation and bidirectional quantum-dot nuclear-spin polarization
By C. Latta, A. Högele, Y. Zhao, A. N. Vamivakas, Patrick Maletinsky, M. Kroner, J. Dreiser, I. Carusotto, Antonio Badolato, D. Schuh and 3 more. 2009
169 citations recorded by the source corpus.
Resonant laser scattering along with photon correlation measurements established the atom-like character of quantum dots. Here, we show that for a wide range of experimental parameters it is impossible to isolate elementary quantum-dot excitations from a strong influence of nuclear spins; the absorption lineshapes at magnetic fields exceeding 1 T indicate that the nuclear spins get polarized by an amount that ensures locking of the quantum-dot resonance to the incident laser frequency. In stark contrast to earlier experiments, this nuclear-spin polarization is bidirectional, allowing the combined electron–nuclear-spin system to track the changes in laser frequency dynamically on both sides of the resonance. This unexpected feature stems from a competition between two spin-pumping processes that attempt to polarize nuclear spins in opposite directions. We find that the confluence of laser excitation and nuclear-spin polarization suppresses the fluctuations in resonant absorption. A master-equation analysis suggests narrowing of the nuclear-spin distribution, pointing to applications in quantum information processing. In semiconductor quantum dots, interactions between the confined electrons and the surrounding reservoir of nuclear spins limit the attainable electron-spin coherence. But the nuclear-spin reservoir can also take a constructive role, as it facilitates the locking of the optical quantum-dot resonance to the changing frequency of an external driving laser, as an experiment now demonstrates.
Subfields: Atomic and Molecular Physics, and Optics
View Paper: https://www.semanticscholar.org/paper/c0586993195cd7f1e068c9e2aca552b4803d8cc9
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In Atomic and Molecular Physics, and Optics
Citations in the corpus
- Nuclear spin physics in quantum dots: an optical investigation (2012, methodology): “Figure 6(d) represents a highly unusual absorption spectrum at Bz = 4.5 T, that is strongly broadened, asymmetric and changes with laser scan direction (Latta et al., 2009).”