Dr. Daniel Urban deutschenglish  

  That's me!  

Physikalisches Institut
Hermann-Herder-Str. 3
79104 Freiburg

E-mail: daniel.urban@iwm.fraunhofer.de



  Research Topics deutschenglish  

  My research interests are within the field of electron transport in nanostructures. When the system size approaches the nano scale, quantum mechanical effects become important and start to dominate over the ''classical physics'' that we are custom with from every-day life. Besides a fundamental interest in these quantum phenomena they are foreseen to become essential to prospective nanoelectronic devices and fundamental to a possible realization of a quantum computer in the future.
During my PhD I examined metallic nanowires, 3-dimensional wires with a diameter of only a few atoms thickness. The remarkable stability of these ''ultimate'' conductors turned out to be due to a particular electronic shell filling, an archetype of a quantum size effect. With a comprehensive stability analysis we could relate the experimentally observed quantized conductance values with the energetically favourable geometric configurations of the nanowires and shed light on their interplay with symmetry breaking deformations and scaling laws.
Subsequently I started to study the noise properties of mesoscopic conductors. Current and charge fluctuations contain various informations on the system and the underlying interactions. Since the higher order moments of the distribution of transmitted charges through a conductor are small and hard to observe experimentally, effective detectors have to be designed and respective theoretical models have to be developed. Here I worked on the theory of the Josephson junction threshold detector and on the problem of heating effect through phonons on the full counting statistics of a molecular junction or atomic wire.
In parallel, I recently started the study of two dimensional lattice systems which can be described by a Dirac-like equation of a pseudo spin 1. These lattices are in some respect similar to graphene (described by a pseudo-spin 1/2 Dirac equation) but generalize this concept to the realm of integer spin and show a number of new and interesting aspects. We investigate these lattices also in the perspective of the emergence of topological states of matter.

My current line of research includes
  • Electron Transport in Nanostructures
  • Noise Properties of Mesoscopic Conductors (full counting statistics)
  • Quantum transport out of equilibrium
  • Graphene and related lattice systems of pseudo spin 1
  • Topological states of matter