Interference effects in the Coulomb blockade regime: current blocking and spin preparation in symmetric nanojunctions

TL;DR

This paper explores interference effects in symmetric nanojunctions within the Coulomb blockade regime, demonstrating current blocking and spin state preparation through a formalism applicable to spin-polarized leads, exemplified by a triple quantum dot SET.

Contribution

It introduces a general formalism for interference blockade in symmetric nanojunctions with spin polarization, enabling spin state control without magnetic fields.

Findings

Interference causes current blocking at specific bias and gate voltages.

The formalism applies to systems with spin-polarized leads.

Selective spin triplet state preparation is demonstrated.

Abstract

We consider nanojunctions in the single-electron tunnelling regime which, due to a high degree of spatial symmetry, have a degenerate many body spectrum. As a consequence, interference phenomena which cause a current blocking can occur at specific values of the bias and gate voltage. We present here a general formalism to give necessary and sufficient conditions for interference blockade also in the presence of spin polarized leads. As an example we analyze a triple quantum dot single electron transistor (SET). For a set-up with parallel polarized leads, we show how to selectively prepare the system in each of the three states of an excited spin triplet without application of any external magnetic field.