(December 23, 2015) A
study led by Ángel Rubio, the UPV/EHU-University of the Basque Country
professor and head of the Max Planck Institute in Hamburg, shows that it is
possible to predict the effects of photons on materials
Computer simulations that predict the light-induced change
in the physical and chemical properties of complex systems, molecules,
nanostructures and solids usually ignore the quantum nature of light.
Scientists at the Max-Planck Institute for the Structure and Dynamics of Matter
(MPSD), led by Professor Ángel Rubio of the UPV/EHU's Department of Material
Physics and Director of the Theory Department at the MPSD, have now shown how
the effects of the photons can be properly included in such calculations. This
study opens up the possibility of predicting and controlling the change of
material properties due to the interaction with photons from first principles.
The basic building blocks of atoms, molecules and solids are
positively charged nuclei and negatively charged electrons. Their mutual
interactions determine most of the physical and chemical properties of matter,
such as electrical conductivity or the absorption of light. The laws that govern
this delicate interplay between electrons and nuclei are those of quantum
electrodynamics (QED), in which particles interact via the exchange of photons,
which are the quanta of light. However, the equations of QED are so complex
that in practice scientists have to simplify them to be able to make any
prediction for real materials. A very common simplification in quantum
chemistry and solid-state physics is to neglect the quantum nature of light.
Although this assumption works well for many applications, recent experiments
have uncovered situations where the quantum nature of the photons can
dramatically change the material properties and give rise to new collective
behaviour and phenomena.