Biomedical subjects

T Nussbaumer

Publications and source records attributed to T Nussbaumer.

3 recordsLinked to original sources

PubMed2003

Multiple Andreev reflections in a carbon nanotube quantum dot.

We report resonant multiple Andreev reflections in a multiwall carbon nanotube quantum dot coupled to superconducting leads. The position and magnitude of the subharmonic gap structure is found to depend strongly on the level positions of the single-electron states which are adjusted with a gate electrode. We discuss a theoretical model of the device and compare the calculated differential conductance with the experimental data.

Journal Article↗

PubMed2002

Quantum dot in the Kondo regime coupled to superconductors.

The Kondo effect and superconductivity are both prime examples of many-body phenomena. Here we report transport measurements on a carbon nanotube quantum dot coupled to superconducting leads that show a delicate interplay between both effects. We demonstrate that the superconductivity of the leads does not destroy the Kondo correlations on the quantum dot when the Kondo temperature, which varies for different single-electron states, exceeds the superconducting gap energy.

Journal Article↗

PubMed2002

Multiwall carbon nanotubes as quantum dots.

We have measured the differential conductance of individual multiwall carbon nanotubes. Coulomb blockade and energy level quantization are observed. The electron levels are nearly fourfold degenerate (including spin) and their evolution in magnetic field (Zeeman splitting) agrees with a g factor of 2. In zero magnetic field the sequential filling of states evolves with spin S according to S = 0-->1/2-->0.... A Kondo enhancement of the conductance is observed when the number of electrons on the tube is odd.

Journal Article↗