Two leading University of California researchers, one a physicist, the other a mathematician, will be joining the Cornell faculty in the coming months. The hirings are regarded as a major coup for the university, since both are seminal figures in their fields. J.C. Séamus Davis, professor of physics at UC-Berkeley, is on the leading edge of the development of scanning tunneling microscopy as applied to superconductivity and quantum computing semiconductors. William Thurston, professor of mathematics at UC-Davis (Read Thurston's profile), is a world-renowned topologist, with a keen interest in the application of computing to mathematics.
Below the basement of Clark Hall, concrete is being poured into a vast, echoing cavern that in months to come will be the foundation for one of the top low-vibration laboratories in the world. Into the lab will go different types of ultra high-precision measuring equipment, including three highly specialized scanning tunneling microscopes (STMs), cooled to temperatures as low as one hundredth of a degree above absolute zero (minus 459.67 degrees Fahrenheit).
From these machines over the next few years will come precision measurements in such areas as the study of individual impurity, or dopant, atoms in important materials. The lab will conduct studies in quantum nanofluidics and the superfluid Josephson effect and perform new kinds of high-precision force measurements at the atomic scale, searching for anomalies in the fundamental force of gravity.
The outcome of this remarkably technical, highly advanced and very expensive, research? "I really don't know exactly where this research will lead ultimately," said J.C. Séamus Davis, professor of physics at the University of California-Berkeley (where he earned his Ph.D. in physics in 1989). "It is exploratory."
Davis, an affable Irishman with curly hair and a rapid-fire delivery, will arrive at Cornell after Thanksgiving to take up his new post as professor of physics associated with the Laboratory of Atomic and Solid State Physics. It is, said Albert Sievers, Cornell professor of physics, "a significant hire for us. He is definitely one of the most exciting scientists in his field."
Besides his STM's and other machines, Davis will be bringing a fistful of government contracts to Cornell. They include:
Indeed, Davis is involved in so many fields, it is difficult to pin him down on his priorities. But when pressed, he said, "I have long been interested in studying the physics of individual dopant atoms and their effect on high Tc [transition temperature] superconductors at the atomic scale. I'm now interested in individual dopant atoms in semiconductors, possibly for use as quantum computers. And in the future, I hope to extend the application of these techniques to new areas such as molecular electronics."
What he seems most excited about, though, is building the next generation of STM, the SJTM (for scanning Josephson tunneling microscope) -- the world's first. This will be a microscope maintained within a hair of absolute zero that will be able, for the first time, to image an Alice in Wonderland world of high-Tc superconductivity.
An STM, such as the three that will be installed in the Clark Hall basement, images the non-superconducting component of the electronic structure of a superconducting material -- that is, one capable of conducting electricity with virtually no resistance. But the SJTM would image the wave function of the electronic state of the superconducting electrons themselves. "High-Tc superconductivity has a lot of mysterious properties," said Davis. "By using an SJTM, you could directly image that quantum state."
Exploring superconductivity is just one of Davis' many research fields. A major part of this program has been experimenting with high Tc superconductors called copper oxide ceramics. Although a long way from the holy grail of a room temperature superconductor, these materials do not have to be quite so frigid as the close-to-absolute-zero temperatures required for metal alloy superconductors. The reason for this, Davis and his collaborators reported in the journal Nature earlier this year, is that a different mechanism accounts for superconductivity in high Tc ceramics.
They showed this by replacing the copper atoms in the ceramic with zinc impurities, or dopants. They then used an STM to verify that high Tc superconductivity is mediated by strongly interacting paired electrons. They thus confirmed the actual physics of high Tc superconductivity. Davis believes that this has opened the potential for developing exotic new superconducting materials, such as Tc cuprates.
"We know of no reason why a room-temperature superconductor is not on the horizon," said Davis. However, he cautions, "if the rate of progress of fundamental understanding of the phenomenon remains the same, "it could also be a very long time before we ever break through to a room temperature superconductor."
In the meantime, he is happy to put down his roots in his new basement lab in Clark Hall. "I admire Cornell greatly, and I like the environment very much. And the great support we are receiving for our research programs is very appealing," he said.
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