Jan Zaanen (born 17 April 1957) 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. Zaanen's areas of interest are in the search for novel forms of collective quantum phenomena realized in systems build from mundane constituents like electrons, spins, and atoms. He introduced the so-called Zaanen-Sawatzky-Allen diagram, the LDA+U band structure method and he became particularly well known for his discovery of the stripe instability of the doped Mott insulator. His present research is focused on the quantum critical point and unconventional phases of quantum matter. He is a well-known proponent of the application of Holographic principle to condensed matter physics. He is also well known for his many editorial contributions to the journals Nature and Science. He is currently on the board of reviewing editors of the latter journal and also editor of the Journal of High Energy Physics. Career Jan Zaanen was born on 17 April 1957 in Leiden. He received his degree in chemistry with honours in 1982 at the University of Groningen, where he also received his doctorate four years later, again with honours. He was under supervision with Spinoza Prize winner George Sawatzky. After a postdoctoral fellowship at the Max Planck Institute for Solid State Research in Stuttgart, he worked for some years as a researcher at AT&T Bell Laboratories in the USA. In 1993 Zaanen returned to the Netherlands, where he worked at Leiden University as a Royal Netherlands Academy of Arts and Sciences (KNAW) fellow. He has been a professor at Leiden since 2000. Furthermore, in 2004 he was appointed as a visiting professor for one year at Stanford University. In 2004-2005 he spent a year at Stanford University sponsored by the Fulbright Program and in 2006 he received the Spinoza Prize, the "Dutch Nobel prize", for his scientific accomplishments. Recently Zaanen is one of the driving forces behind the scientific cooperation between the fields of string theory and high-temperature superconductivity. In an interview with Dutch newspaper, De Volkskrant, he stated: After winning the Spinoza Prize, it was no longer necessary to worry whether I was proving myself enough. You start looking at things you really like. Furthermore I wanted to prove that I was not too old to learn new things. String theory