Research: Signatures of quantum anomaly found

In the latest issue of the magazine „Nature“, an international team of scientists including
Dr. Tobias Meng from the Institute of Theoretical Physics of the TU Dresden reports on the
observation of a long sought-after quantum effect. Despite having been discussed since
the 1970s, the effect of the name of „axial-gravitational quantum anomaly“ has only now
been demonstrated for the first time.

Thus far, it was believed that this effect could only be measured in extreme conditions, for
instance in neutron stars. This precluded its observation in the past. In an experiment
performed at the IBM research center in Zürich, however, the scientists have now
succeeded in establishing evidence for the axial-gravitational quantum anomaly in a metal
composed of the chemical elements niobium and phosphor. Tobias Meng, who has only
recently been selected for the prestigious Emmy Noether programme by the Deutsche
Forschungsgemeinschaft, played a vital role in interpreting the experimental data.

„With the experiment we could show that the energy of Weyl particles, named after the
physicist Hermann Weyl, does not follow the same laws as for regular particles“, Tobias
Meng asserts. The work thus closes a gap between the theoretical understanding that
physicists have of Weyl particles, and the prior experimental results. This is also of interest
beyond the fundamental science community: Weyl particles conduct current especially
well, and could thus speed up future computers. „To render such improvements in
everyday life possible, it is crucial for us to really understand the properties of Weyl
particles. I am happy that our work makes an important contribution to that effort“, Tobias
Meng states.

J. Gooth, A. C. Niemann, T. Meng, A. G. Grushin, K. Landsteiner, B. Gotsmann, F. Menges, M. Schmidt, C. Shekhar, V. Süß, R. Hühne, B. Rellinghaus, C. Felser, B. Yan, K. Nielsch,
Nature 547, 324 (2017)