Letter abstract
Nature Physics 5, 321 - 326 (2009)
Published online: 6 April 2009 | doi:10.1038/nphys1247
Subject Categories: Nanotechnology | Condensed-matter physics
Electron–nuclear interaction in 13C nanotube double quantum dots
H. O. H. Churchill1, A. J. Bestwick1, J. W. Harlow1, F. Kuemmeth1, D. Marcos1,2, C. H. Stwertka1, S. K. Watson1,2 & C. M. Marcus1
For coherent electron spins, hyperfine coupling to nuclei in the host material can either be a dominant source of unwanted spin decoherence1, 2, 3 or, if controlled effectively, a resource enabling storage and retrieval of quantum information4, 5, 6, 7. To investigate the effect of a controllable nuclear environment on the evolution of confined electron spins, we have fabricated and measured gate-defined double quantum dots with integrated charge sensors made from single-walled carbon nanotubes with a variable concentration of 13C (nuclear spin I=1/2) among the majority zero-nuclear-spin 12C atoms. We observe strong isotope effects in spin-blockaded transport, and from the magnetic field dependence estimate the hyperfine coupling in 13C nanotubes to be of the order of 100 
eV, two orders of magnitude larger than anticipated8, 9. 13C-enhanced nanotubes are an interesting system for spin-based quantum information processing and memory: the 13C nuclei differ from those in the substrate, are naturally confined to one dimension, lack quadrupolar coupling and have a readily controllable concentration from less than one to 105 per electron.
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Present addresses: Departamento de Teoría de la Materia Condensada, Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco 28049, Madrid, Spain (D.M.); Department of Physics, Middlebury College, Middlebury, Vermont 05753, USA (S.K.W.)
Correspondence to: C. M. Marcus1 e-mail: marcus@harvard.edu
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