Electrical Properties of Quantum Dot Systems

Quantum dots, also denoted as artifical atoms or zero-dimensional electron systems, are objects where few to many electrons are confined in a small spatial enclosure of mesoscopic size (few tens to few hundreds of nanometers), allowing a single electron only certain eigenvalues for its energy (‘quantum mechanical particle in a box’).

Quantum dots weakly linked to leads (‘source’ and ‘drain’) by quantum mechanical tunneling through energy barriers can be considered as model systems to study fundamental aspects of electrical transport through single atoms or molecules. Especially the number of electrons confined on the quantum dot can be controlled electrostatically by nearby gate electrodes.

Quantum dot systems can be designed to purpose since they are usually fabricated by conventional semiconductor growth and processing technology. Drawback of their mesoscopic size is that exploring their electrical properties requires low temperature (below 0.1 Kelvin).

Coulomb blockade and single-electron charging are observed in electrical transport as a consequence of the repelling electrostatic electron-electron interaction in quantum dots. Such quantum dot systems behave as single-electron transistors.

However, the degree of freedom in occupying the quantum dot either with the electron spin orientation up or down can cause with lowering the temperature a peculiar quantum dynamics, overcoming the Coulomb blockade of the quantum dot system. The effect can be described in the framework of Kondo physics.

Astonishingly at first view, even the arrangement of two quantum dot systems – interacting purely electrostatically – can behave as a pseudo-spin Kondo system.


Publications on Quantum Dot Systems

Spectroscopy of Ground and Excited States of the Confined Electron System
in a Quantum Dot by Electrical Transport Measurements

Constant Interaction Model – An Adequate Description for the Confined Electron System in a Quantum Dot?   more

Spin Kondo Physics in Quantum Dot Systems   more

Quantum Dot System in High Magnetic Fields: Chess Board Pattern of Kondo-Correlated States   more

Two Electrostatically Coupled Quantum Dot Systems as a Pseudo-Spin Kondo System   more

Quantum Dot with Three Leads: Single-Electron Transistor with Current Gain

Quantum Dot System Exposed to AC Fields   more

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