Physicists discover novel quantum effect

Most laptop users notice it skin deep: when you place your mobile companion on your lap and go surfing the internet for a while, the computer gets really warm. For the average user this may not seem such a big deal. But heating really poses a problem for the semiconductor industry, because heat development severely limits the development of future generations of chips – and thus of laptops, and PC's in general.

The market demands ever improving performance from chips and computer. To satisfy this demand, more and more transistors must be crammed into the same surface area, and when an electrical current it applied to these transistors, they produce considerable heat. “To increase the speed of a computer, one must increase the amount of current flowing through its chips, thus increasing the side effect of heating” explains Prof. Hartmut Buhmann, responsible for the team conducting the research. “This may bring about so much heat that temperature becomes the limiting factor in performance.” Actually, high performance computers already today use water cooling to deal with this issue.

“The techniques that we have recently discovered here in Wuerzburg could alleviate the issue of chips overheating” says Prof. Laurens W. Molenkamp, head of the chair for experimental physics III: “Using the quantum spin Hall effect which we for the first time have demonstrated here, it is possible to transport and manipulate information without energy loss.” This means that a future computer could operate extremely fast without losing its cool!

For discoveries in this vein, Wuerzburg University appears to be the place to be. 25 years earlier, at the same chair, then headed by Gottfried Landwehr, Klaus von Klitzing made the discovery of the (charge) quantum Hall effect, which determines the Hall resistance of a semiconductor field effect transistor in a strong magnetic field, and for which he was awarded the Nobel prize for physics in 1985.

Further information:
Prof. Dr. Hartmut Buhmann, ++49 (931) 888-5778, hartmut.buhmann@physik.uni-wuerzburg.de

Prof. Dr. Laurens Molenkamp, ++49 (931) 888-4925, molenkamp@physik.uni-wuerzburg.de

Markus König1, Steffen Wiedmann1, Christoph Brüne1, Andreas Roth1, Hartmut Buhmann1, Laurens W. Molenkamp1, Xiao-Liang Qi2, and Shou-Cheng Zhang2: “Quantum Spin Hall Insulator State in HgTe Quantum Wells”, Science, published online on September 20, 2007, DOI: 10.1126/science.1148047

1Physikalisches Institut (Lehrstuhl für Experimentelle Physik III), Universität Würzburg, D-97074 Würzburg, Germany

2Department of Physics, McCullough Building, Stanford University, Stanford, CA 94305-4045, USA