The full university professor of the Universitat de València Alfredo Segura gives this Tuesday at 12:30h a Severo Ochoa colloquium at the IFIC in order to address the last Nobel Prize for Physics, awarded to the English researchers David J. Thouless, F. Duncan M. Haldane and J. Michael Kosterlitz for their discoveries in the transitions of the topological phases of the matter. These studies contribute to understand the operation of some types of magnets and superconductor fluids, as well as the quantum behaviour of certain systems.
The Nobel Prize for Physics in 2016 was awarded to the researcher David J. Thouless (Washington U., USA), together with F. Duncan M. Haldane (Princeton U., USA) and J. Michael Kosterlitz (Brown U., USA) “for their theoretical discoveries about the transitions of topological phases of the matter”. The aim of this talk is to present a brief version of the main innovations introduced by the winners, as well as to show the high influence of their ideas in the different areas of Physics of condensed matter.
After introducing some basic notions about topology, it will be discussed in the colloquium which contexts are suitable for the description of the electronic structure of solids. Apart from the quantum numbers derived from fundamental symmetries, the winners of the Nobel have shown that it is possible to introduce topological quantum numbers: while the formers are extremely sensitive to the imperfections of the materials, the latter are strong and can be with difficulty affected by these imperfections. They create phenomena such as Hall effect in which, no matter the design of the system and its imperfections, the physic response is controlled by a universal constant (Von Klitzing constant).
The phase transition concept associated with a given symmetry breaking is applied to the transitions between ‘ordinary’ states of the condensed matter. It cannot cover some physic effects that occur in systems of small dimensions (electronics, magnetics, superfluids, etc.) related to changes in topological structures due to imperfections or the excitation of the system. This influential idea, introduced by Thouless, Haldane and Kosterlitz, can describe and systematised the great variety of exotic states discovered in systems of small dimensions (such as the solid fusion 2D, superfluid or superconductor thin films, 2D networks of unions under the Josephson effect, 1D and 2D spin systems, etc.).
More information:
https://www.nobelprize.org/nobel_prizes/physics/laureates/2016/
http://indico.ific.uv.es/indico/conferenceDisplay.py?confId=2919