Workshop book - Physikzentrum der RWTH Aachen - RWTH Aachen ...
Workshop book - Physikzentrum der RWTH Aachen - RWTH Aachen ...
Workshop book - Physikzentrum der RWTH Aachen - RWTH Aachen ...
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Talks Wednesday February 6<br />
Level structure and tunnel coupling of carbon nanotube quantum dots<br />
Kasper Grove-Rasmussen, University of Copenhagen, Denmark<br />
We present our current un<strong>der</strong>standing of the quantum states in a carbon<br />
nanotube quantum dot deduced from low temperature transport measurements<br />
in parallel and perpendicular magnetic fields. The observed energy<br />
spectrum is shown to be or<strong>der</strong>ed in shells of two doublets consistent with a<br />
single-particle four-state model including spin-orbit interaction, intra-shell<br />
valley mixing and an orbital g-factor. To fully capture the behavior in the<br />
multi-shell case, additional inter-shell valley mixing parameters are needed,<br />
describing valley mixing between states belonging to different shells [1, 2].<br />
Furthermore, for certain shells, the two doublets are observed to be differently<br />
coupled to the leads, resulting in gate-dependent level renormalization.<br />
By comparison to the one-shell model this is shown to be a consequence<br />
of intra-shell valley mixing in the nanotube. Moreover, a parallel magnetic<br />
field is shown to reduce this mixing and thus suppress the effects of tunnelrenormalization<br />
[3].<br />
[1] T. Sand Jespersen, K. Grove-Rasmussen, J. Paaske, K. Muraki, T. Fujisawa,<br />
J. Nygård, and K. Flensberg, Nat. Phys. 7, 348 (2011).<br />
[2] T. S. Jespersen, K. Grove-Rasmussen, K. Flensberg, J. Paaske, K.<br />
Muraki, T. Fujisawa, and J. Nygård, Phys. Rev. Lett. 107, 186802 (2011)<br />
[3] K. Grove-Rasmussen, S. Grap, J. Paaske, K. Flensberg, S. An<strong>der</strong>gassen,<br />
V. Meden, H. I. Jørgensen, K. Muraki, and T. Fujisawa, Phys. Rev. Lett.<br />
108, 176802 (2012).<br />
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