Level-occupation switching of the Quantum Dot, and phase anomalies in mesoscopic interferometry

TL;DR

This paper investigates how occupation switching in quantum dots with levels of vastly different widths affects electron transmission and phase behavior, providing explanations for observed phase anomalies and exploring the Kondo regime.

Contribution

It introduces a unified theory explaining Coulomb blockade peak patterns and phase anomalies due to level occupation switching, emphasizing the role of interactions.

Findings

Consecutive Coulomb blockade peaks can originate from a single broad level.

Electron jumps between broad and narrow levels cause phase lapses in interferometry.

The theory accounts for experimental transmission phase behavior and approaches to the Kondo regime.

Abstract

For a variety of quantum dots, the widths of different single-particle levels may naturally differ by orders of magnitude. In particular, the width of one strongly coupled level may be larger than the spacing between other, very narrow, levels. We found that in this case many consecutive Coulomb blockade peaks are due to occupation of the same broad level. Between the peaks the electron jumps from this level to one of the narrow levels and the transmission through the dot at the next resonance essentially repeats that at the previous one. This offers a natural explanation of the salient features of the behavior of the transmission phase in an interferometer with a QD. The theory of this effect will be reviewed with special emphasis on the role of the interactions. New results on the dot-charging measurements and the fine structure of occupation switchings will be presented, accompanied by the unified description of the whole series of CB peaks caused by a single broad level. We then discuss the case where the system approaches the Kondo regime.