Jury report for Prof. L.P. (Leo) Kouwenhoven

Professor of Quantum Transport at Delft University of Technology

Professor Kouwenhoven receives the NWO/Spinoza Prize 2007 for his breakthroughs in the area of quantum transport in semiconducting materials. His groundbreaking work on so-called spin qubits is of vital importance for the use of quantum information, for example, in a fundamentally new type of computer.

Leo Kouwenhoven (10 December 1963) studied technical physics at Delft University of Technology and gained his doctorate with distinction there in 1992. From 1993 to 1998 he was a Royal Netherlands Academy of Arts and Sciences fellow at this university; he spent part of this period at Berkeley. In 1999 he was offered a professorship by Harvard. He turned this down to become a professor at Delft. Since 2001 he has been a member of the physics faculty at Harvard. In 2002 he received a Vici subsidy from NWO and in 2004 he received nine million euros from the Foundation for Fundamental Research on Matter (FOM) for a 10-year research programme with Leiden University into quantum information. Since 2006 he has been a member of the Royal Netherlands Academy of Arts and Sciences (KNAW).

Leo Kouwenhoven is a world leader in the area of electronic properties of nanostructures. His exceptional scientific talent was already apparent in his student years. As a student he was involved in the discovery that electrical conduction in point contacts is quantised. This means that the degree of conductance can only be in whole multiples of fundamental units. His doctoral thesis contained no less than 6 top publications. Kouwenhovens impact on the research field of mesoscopic phenomena was already considerable before he obtained his doctorate.

The physicist from Delft is responsible for a number of major breakthroughs in his field. As a driving force in his discipline he has made his mark in the research of quantum dots. These are minuscule structures in semiconducting material that exhibit special quantum properties due to their small dimensions. Together with his Japanese colleague Tarucha, he discovered that circular quantum dots had an electronic structure similar to that of electron shells in atoms. Their 'periodic system of two-dimensional elements' gained considerable fame and partly as a result of this the structures gained the name 'artificial atoms'.

At present Kouwenhoven is using the spin of electrons in quantum dots as qubits: the calculating unit of a quantum computer. His group was the first to read the spin state of a single electron. In 2006 they managed to manipulate this property. This is a major step on the way to a quantum computer, which calculates with so-called superpositions of spin states.

Kouwenhoven is a very productive scientist. During his relatively short career to date he has published more than 180 articles, of which 17 in Science and Nature. Seven of his articles have reached the front cover of a journal. During its first three years the large-scale FOM programme with Leiden University has already led to more than 20 publications in Nature, Science and Physical Review Letters.

Kouwenhoven’s work is of major significance from a practical as well as a scientific viewpoint. He works very closely with industry. More than one-quarter of his articles have been co-authored with industrial partners. He is good at inspiring people and knows how to attract new talent. The Spinoza committee therefore has the fullest confidence that the NWO/Spinoza Prize has rightfully been given to Kouwenhoven and will form the basis for new breakthroughs within nanophysics.

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This jury report served as the basis for the speech given by Prof. Maarten Koornneef at the announcement of the NWO/Spinoza Prizes 2007 on 4 June 2007.