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Lecture Dominik Zumbuhl


12 July 2012 FWN-Building 5111.0080, Nijenborgh 4, 9747 AG, Groningen
Speaker: Prof. Dr. Dominik Zumbuhl
Affiliation: Physics Department, University of Basel, Switzerland
Title: Nuclear spin order and intrinsic charge fluctuations GaAs nanostructures
Date: Thu Jul 12, 2012
Start: 16.00
Location: FWN-Building 5111.0080
Host: C.H. van der Wal
Telephone: +31 50 363 4555


I will present low-temperature quantum transport measurements of GaAs cleaved-edge overgrowth wires. The conductance of the lowest wire mode approaches the 2 e2/h at high temperatures but is suppressed strongly

for decreasing temperatures, reaching 1 e2/h at ~ 80 mK, where it remains for T< 80 mK. We have confirmed that the electrons cool to about 10 mK, well below 80 mK. This suggests that the electron spin degeneracy is fully lifted (B= 0), presenting evidence for a strong nuclear spin polarization. Our data are qualitatively consistent with recent theory predicting a spin-selective Peierls transition in the Luttinger liquid regime, presenting experimental evidence for a helical nuclear state.


Further, I will present experimental data and theory for intrinsic charge fluctuations and metastable states in GaAs surface-gate defined double quantum dots in the few electron regime. These charge fluctuations set an intrinsic upper limit for spin-qubit coherence and can be suppressed by reducing temperature and/or tunnel-coupling of the dots to the reservoirs.

Last modified:22 October 2012 2.30 p.m.