Quantum physics: First images of Landau levels revealed

Physicists have directly imaged Landau Levels -- the quantum levels that determine electron behaviour in a strong magnetic field -- for the first time since they were theoretically conceived of by Nobel prize winner Lev Landau in 1930.

Using scanning tunnelling spectroscopy -- a spatially resolved probe that interacts directly with the electrons -- scientists at institutions including the University of Warwick and Tohoku University have revealed the internal ring-like structure of these Landau Levels at the surface of a semiconductor.

The experimental challenge in the work was to have sufficient spatial resolution in order to overcome the intrinsic disorder in the material which usually only allows the observation of smeared out "drift" states.

The images clearly show that Landau was right when he predicted that, in a clean system, the electrons would take on the form of concentric rings, the number of which increase according to their energy level.

This simple counting behaviour forms the basis of the so-called quantum Hall effect.