Jan Zaanen (born 17 April 1957, Leiden) is Professor of Theoretical Physics at Leiden University, The Netherlands. He is best known for his contributions to the understanding of the quantum physics of the electrons in strongly correlated material, and in particular High temperature superconductivity. He introduced the Zaanen-Sawatzky-Allen diagram, the LDA+U band structure method and he became particular well known for his discovery of the stripe instability of the doped Mott insulator. His present research is focussed on the Quantum Critical Point and unconventional phases of quantum matter. He is also well known for his many editorial contributions to Nature and Science. He is at present on the board of reviewing editors of the latter journal.
In 2004-2005 he spent a year at Stanford University sponsored by the Fulbright Program and in 2006 he received the Spinozapremie, the "Dutch Nobel prize", for his scientific accomplishments.
Over this past year, Zaanen and his colleagues Cubrovic and Schalm, applied String theory for the first time to explain a physical phenomen.
Zaanen was able to explain the quantum-critical state of electrons, the state that occurs in materials just before they become super-conductive in high temperature. "It has always been assumed that once you understand this quantum-critical state, you can also understand high temperature super-conductivity. But, although the experiments produced a lot of information, we hadn't the faintest idea of how to describe this phenomenon," Zaanen stated. "We hadn't expected it to work so well, the maths was a perfect fit; it was superb. When we saw the calculations, at first we could hardly believe it, but it was right."