Non-equilibrium transport through a vertical quantum dot in the absence of spin-flip energy relaxation

TL;DR

This paper explores non-equilibrium transport phenomena in a quantum dot without spin-flip relaxation, revealing novel tunneling processes and fluctuations not explained by traditional Coulomb blockade theory.

Contribution

It uncovers new high-spin tunneling processes and charge fluctuations in quantum dots lacking spin relaxation, expanding understanding of non-equilibrium quantum transport.

Findings

Observation of high-spin tunneling processes

Detection of charge and energy fluctuations

Deviation from orthodox Coulomb blockade theory

Abstract

We investigate non-equilibrium transport in the absence of spin-flip energy relaxation in a few-electron quantum dot artificial atom. Novel non-equilibrium tunneling processes involving high-spin states which cannot be excited from the ground state because of spin-blockade, and other processes involving more than two charge states are observed. These processes cannot be explained by orthodox Coulomb blockade theory. The absence of effective spin relaxation induces considerable fluctuation of the spin, charge, and total energy of the quantum dot. Although these features are revealed clearly by pulse excitation measurements, they are also observed in conventional dc current characteristics of quantum dots.