title: Triple quantum dots as charge rectifiers.
abstract: We theoretically analyze electronic spin transport through a triple quantum dot in series, attached to electrical contacts, where the drain contact is coupled to the central dot. We show that current rectification  is observed in the device due to current blockade. The current blocking mechanism is originated by a destructive interference of the electronic wavefunction at the drain dot. There, the electrons are coherently trapped in a singlet two-electron dark state, which is a coherent superposition of the electronic wavefunction in the source dot and in the dot isolated from the contacts. Its formation gives rise to zero current and current rectification as the voltage is swept. We analyze this behavior analytically and numerically for both zero and finite magnetic dc fields. On top of that, we include phenomenologically a finite spin relaxation rate and calculate the current numerically. Our results show that triple dots in series can be designed to behave as quantum charge rectifiers.
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, E-28049 Cantoblanco, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Busl
authors.forename: G
authors.initials: G
authors.lastname: Platero