Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 8: Transport: Quantum dots, wires, point contacts 1 (TT, jointly with HL, O)
HL 8.13: Vortrag
Montag, 11. März 2013, 12:45–13:00, H20
Role of coherent state superpositions in the bipolar spin blockade of a triple quantum dot — Maria Busl1, Ghislain Granger2, Louis Gaudreau2, •Rafael Sánchez1, Alicia Kam2, Michel Pioro-Ladrière3, Sergei Studenikin2, Piotr Zawadzki2, Zbigniew Wasilewski2, Andrew Sachrajda2, and Gloria Platero1 — 1Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Madrid, Spain — 2National Research Council Canada, Ottawa, Canada — 3Université de Sherbrooke, Sherbrooke, Canada
In double quantum dots, Pauli spin blockade manifests as a rectified current: charge flows or is blocked depending on the sign of the applied voltage[1]. We present experimental and theoretical investigations of the equivalent process in triple quantum dots in series. We focus on a configuration where (2,0,2) (2,1,1), (1,1,2) and (2,1,2) states are degenerate. When a bias is applied in a magnetic field beyond 10mT, bipolar spin blockade is observed where current is suppressed independent of the applied bias direction. As the field is reduced to zero, leakage resonances are observed. Of special interest are two very sharp resonances which correspond to triple dot conditions when states in the left and right dot but not the center dot align. One of these resonances is found itself to involve bipolar spin blockade and is found to result from a purely quantum coherent effect: electrons occupy states that involve their transference from one extreme to the other of the triple quantum dot without ever visiting the center[2].
[1] K. Ono et al., Science 297, 1313 (2002).
M. Busl et al., unpublished.