Confluence of resonant laser excitation and bidirectional quantum-dot nuclear-spin polarization

Latta, C. et al. (2009) Confluence of resonant laser excitation and bidirectional quantum-dot nuclear-spin polarization. Nature Physics, 5(10), pp. 758-763. (doi: 10.1038/nphys1363)

Abstract

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.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Badolato, Professor Antonio
• Authors: Latta, C., Högele, A., Zhao, Y., Vamivakas, A.N., Maletinsky, P., Kroner, M., Dreiser, J., Carusotto, I., Badolato, A., Schuh, D., Wegscheider, W., Atature, M., and Imamoglu, A.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Nature Physics
• Publisher: Nature Publishing Group
• ISSN: 1745-2473
• ISSN (Online): 1745-2481
• Published Online: 16 August 2009