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arXiv · 1310.5269

Bipolar spin blockade and coherent state superpositions in a triple quantum dot

M. Busl·G. Granger·L. Gaudreau·R. Sánchez·A. Kam·M. Pioro-Ladrière·S. A. Studenikin·P. Zawadzki·Z. R. Wasilewski·A. S. Sachrajda·G. Platero
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Abstract

Spin qubits based on interacting spins in double quantum dots have been successfully demonstrated. Readout of the qubit state involves a conversion of spin to charge information, universally achieved by taking advantage of a spin blockade phenomenon resulting from Pauli's exclusion principle. The archetypal spin blockade transport signature in double quantum dots takes the form of a rectified current. Currently more complex spin qubit circuits including triple quantum dots are being developed. Here we show both experimentally and theoretically (a) that in a linear triple quantum dot circuit, the spin blockade becomes bipolar with current strongly suppressed in both bias directions and (b) that a new quantum coherent mechanism becomes relevant. Within this mechanism charge is transferred non-intuitively via coherent states from one end of the linear triple dot circuit to the other without involving the centre site. Our results have implications in future complex nano-spintronic circuits.

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M. Busl, G. Granger, L. Gaudreau, R. Sánchez, A. Kam, M. Pioro-Ladrière, S. A. Studenikin, P. Zawadzki, Z. R. Wasilewski, A. S. Sachrajda, G. Platero. 2013-10-19. Bipolar spin blockade and coherent state superpositions in a triple quantum dot. https://doi.org/10.1038/nnano.2013.7

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