A temperature of virtually absolute zero, minus 273.15 degrees Celsius, is required to be able to investigate the quantum physical phenomena in which Professor Silke Bühler-Paschen is interested. She is investigating "quantum phase transitions" - abrupt changes of material properties that occur close to absolute zero. Her "QuantumPuzzle" ERC grant has enabled her to explore new avenues and set up a microkelvin low-temperature facility. The new equipment (a mixer-cooler with a core demagnetisation level) is soon to become one of the best of its type in the world. The research unit is being presented as part of an ERC symposium on 22 June 2011.
Unresolved problems in quantum physics
The more particles involved in quantum processes, the more complex quantum physics becomes. Quantum phenomena in solid objects, involving a large number of particles, thus hold mysteries yet to be revealed and have great surprises in store. Amongst these phenomena, which are yet to be fully understood, is superconductivity - the property of certain materials to conduct electricity below a specific temperature without losing any energy - in other words, without any electrical resistance. "Our research area is highly diverse," says Silke Bühler-Paschen. "Very different problems - from creating material samples to cooling technology and theoretical calculations - need to be solved."
One hundred millionth of a degree above absolute zero
Silke Bühler-Paschen and her team have already presented spectacular results from their research. With the cooling system used thus far, it has nevertheless been possible to achieve temperatures of ten to twenty thousandths of a degree above absolute zero - cold enough to detect exotic properties in quantum phase transitions of various materials. In the new microkelvin laboratory, it should now be possible to achieve temperatures of around one hundred millionth of a degree above absolute zero - in other words, 100 times colder than previously. In doing this, researchers hope to be able to really get to the bottom of previous observations. To achieve this required a range of technical tricks. An specialist dampening system had to be installed to counterbalance minimal vibrations of the building. The oscillation of walls and floors, which people would not detect, would transfer energy to the equipment and thus heat it up.
"Taking experiments on quantum phase transitions to such low temperatures is a world first - so we are international pioneers in that respect," says a delighted Silke Bühler-Paschen. Yet it is not actually a low-temperature world record - Bose-Einstein condensates, generated in TU Wien's Institute of Atomic and Subatomic Physics, are even colder - however, relatively few atoms are cooled there. In contrast, in Bühler-Paschen's laboratory, huge solid objects (six whole kilograms of copper) are cooled to inconceivably low temperatures in the millikelvin range. The amount of heat that needs to be extracted is thus incomparably greater.
For Silke Bühler-Paschen, the new mikrokelvin laboratory is a significant step forward. "To understand the materials of the future, we need quantum physical research," she stressed. The mikrokelvin laboratory will provide some key pieces to be able to solve the "quantum puzzle" of low temperature solid-state physics.
Prof. Silke Bühler-Paschen
Institute of Solid State Physics
Wiedner Hauptstraße 8-10, 1040 Vienna
Phone: +43 1 58801 13716
Dr. Florian Aigner
Service Unit of PR and Marketing
Operngasse 11, 1040 Vienna
Phone: +43 1 58801 41027
This research project is located between three of the five research focal areas of the TU Wien: Quantum Physics & Quantum Technologies, Materials & Matter and Energy & Environment. Using the methods of quantum physics, new materials are being researched that could also play an important role in energy and environmental issues in the future.