Electron transport through double quantum dots

TL;DR

This paper reviews electron transport experiments in double quantum dots, highlighting their potential for quantum computing, and discusses how various spectroscopic techniques reveal detailed quantum states and bonding characteristics.

Contribution

It provides a comprehensive overview of experimental techniques and findings on double quantum dots, emphasizing their relevance for solid state quantum bits.

Findings

Resonant tunneling determines intrinsic energy state lifetimes.

Magnetic field studies reveal evolution of energy levels and avoided crossings.

Microwave spectroscopy demonstrates transition from ionic to covalent bonding in double dots.

Abstract

Electron transport experiments on two lateral quantum dots coupled in series are reviewed. An introduction to the charge stability diagram is given in terms of the electrochemical potentials of both dots. Resonant tunneling experiments show that the double dot geometry allows for an accurate determination of the intrinsic lifetime of discrete energy states in quantum dots. The evolution of discrete energy levels in magnetic field is studied. The resolution allows to resolve avoided crossings in the spectrum of a quantum dot. With microwave spectroscopy it is possible to probe the transition from ionic bonding (for weak inter-dot tunnel coupling) to covalent bonding (for strong inter-dot tunnel coupling) in a double dot artificial molecule. This review on the present experimental status of double quantum dot studies is motivated by their relevance for realizing solid state quantum bits.