##
Three-Terminal Transport Spectroscopy of Quantum Dots

### Martin Leijnse

Niels Bohr Institute, University of Copenhagen

**Thursday, 16 September 2010, 11:15**

Matfys library

**Abstract**:

In recent years, devices based on quantum dots formed by gating a
two-dimensional electron gas have found many applications, e.g., in charge
sensing and quantum information. New types of quantum dot devices, based
on nanowires, carbon nanotubes, and even single molecules, have further
interesting properties, such as meta-stable states and non-trivial spin or
mechanical degrees of freedom.
A central problem is that such devices cannot be made in a completely
reproducible or controlled way. Spectroscopic investigation of devices is
therefore of paramount importance. Standard spectroscopic techniques
typically cannot be used to investigate the quantum dots in situ, and the
only remaining option is to measure the current through the device as
function of the applied voltages and use this to extract information about
the dot.
Such transport spectroscopy is the topic of my talk. I will introduce a
theory for transport through strongly interacting dots, which goes beyond
lowest order in the tunnel coupling, and show that this theory predicts a
new type of transport resonance, originating from coherent tunneling of
electron pairs. Furthermore, I will discuss some recent experiments on
different types of dots. Interpreting experimental transport spectra is
often a tricky business, but I will show that a direct comparison to model
calculations can help to uncover the underlying physics.