August 29, 2013

Light on twenty-year-old mystery

Groningen scientists have found an explanation for a mystery that has been puzzling the physics community since 1995. In the scientific journal Nature on Thursday 28 August (Advance Online Publication), they explain why electrons pass through very tiny wires (known as quantum point contacts) less smoothly than expected. The observations of the group led by Prof. C.H. (Caspar) van der Wal of the Zernike Institute for Advanced Materials of the University of Groningen will affect electronics on a nanoscale: ‘Our thinking about this has been too naïve so far.’

The mystery concerns nano wires that are about a hundred atoms wide. As early as 1988, the Dutch physicist Bart van Wees, currently a professor at the Zernike Institute, discovered a remarkable effect in this kind of wire. When he made them wider, the flow did not increase gradually but in a stepwise manner. Van der Wal: ‘This could be explained by quantum effects that occurred in the wires. There is a formula that describes precisely how these steps occur.’