Attractive Coulomb interactions in a triple quantum dot

Abstract

This work demonstrates that electron pairing can be achieved purely by the Coulomb interactions in a triple quantum dot. Such a pairing mechanism is different from that of a Cooper pair. The electron pairing in two dots of the triple dot is mediated by the other (third) dot, when the third dot strongly couples with the two via Coulomb repulsion. By measuring electron conductance through each individual dot, the authors find the degeneracy for the pairing, the condition for the degeneracy, and nontrivial transport behavior by the pairing. These findings may be exploited to design quantum devices with nontrivial electron correlations and functionalities.