Berlin 2015 – scientific programme
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MA: Fachverband Magnetismus
MA 17: Spintronics: Excitons and local spins (HL with MA/TT)
MA 17.4: Talk
Tuesday, March 17, 2015, 10:15–10:30, ER 270
Nuclear magetic resonance on a single quantum dot — •Gunter Wüst1, Mathieu Munsch1, Andreas Kuhlmann1, Martino Poggio1, Arne Ludwig2, Andreas Wieck2, Dirk Reuter3, and Richard J Warburton1 — 1University of Basel, Switzerland — 2Ruhr-Universität Bochum, Germany — 3Universität Paderborn, Germany
The spin coherence of an electron trapped to a GaAs or InGaAs quantum dot is limited by noise in the nuclear spins of the host material [1]. Understanding and controlling the nuclear spins is therefore important for quantum applications. We report here nuclear magnetic resonance (NMR) experiments on the 100,000 nuclear spins that have a contact hyperfine interaction with a quantum dot electron spin [2]. The main technique is to sweep the frequency of an in-plane magnetic field. In this way, all nuclear spins are addressed despite the presence of four main isotopes with different gyromagnetic ratios. The nuclear spins are polarized and read-out via resonant spectroscopy allowing us to reach a sensitivity to about 1,000 nuclear spins. We evidence a plateau in the NMR sweep rate dependence associated to the existence of quadrupole interactions. Detailed analysis allows the quadrupole distributions for each isotope to be determined, along with an effective nuclear spin temperature following polarization (8 mK) and an In concentration (20%). Ongoing experiments determined in addition the Hahn echo coherence times (1 ms) and their dependence on quantum dot charge.
[1] R. J. Warburton et al, Nature Materials 12, 483-493 (2013) [2] M. Munsch, Nature Nanotechnology 9, 671-675 (2014)