February 3, 2011, Nr. 5

4.8 Million Euro for pioneering research in the field of quantum computing

Two physicists at the University of Stuttgart win in the European Research Council’s third “Advanced Grant” competition.

The ERC-„Advanced Grant“ for established research leaders is one of the most prestigious research awards worldwide.  Two physicists at the University of Stuttgart received independently of each other this grant worth 2.4 Million Euro each to promote their pioneering research: Prof. Tilman Pfau, director of the 5th Physics Institute, receives the grant for his research on  the control of quantum correlations in long-range interacting quantum gases. Prof. Jörg Wrachtrup, director of the 3rd Physics Institute, gets the award for the application of defect centers in diamonds in quantum technology. Both fields of research are considered very promising with regard to the realization of quantum computers with high computing power and extremely secure data transfers as well as applications in data processing.

Science minister of Baden-Württemberg Professor Dr. Peter Frankenberg congratulated. „The decision of the European Research Council is an honor and great success for the two scientists and the University of Stuttgart alike. The award is also an indicator on how well Baden-Württemberg is positioned in fundamental research. In this 3 rd competition the ERC awarded altogether six scientists in Baden-Württemberg with an advanced grant”, according to Minister Frankenberg.  
„Over the past few years quantum physics has become a research focus in Stuttgart on an extremely high level“, stated the Rector of the University Prof. Wolfram Ressel. „We are very pleased that this expertise has been acknowledged by the European Research Council now even with two Advanced Grants. This has also a signaling effect with regard to our proposal in the Excellence Initiative by the German federal and states governments. It shows our excellent international standing in quantum physics - also in the cooperation with other research partners.”
ERC Advanced Investigator Grant LIQAD „Long-range interacting quantum systems and devices” (Prof. Tilman Pfau)
In principal the smallest unit of information is a bit which classically can take the value 1 or 0. These two values could also represent true or false, right or left, up or down.  The information era is based on the exchange and efficient processing of such information units. The ultimate capacity limit of data processing is reached by the use of the smallest unit available in nature, which is a single quantum e.g. a single photon. Such quantum information carriers follow the laws of quantum mechanics, where also states of superposition of 0 and 1 are allowed. New kinds of quantum devices are expected to send, receive, store and process these quantum information carriers. This offers new possibilities for secure data transfer and  quantum information processing by logical operations.
On their way to achieve this goal, Prof. Tilman Pfau and his team are following an approach based on atomic gases. In order to process data the single photons have to interact with each other by changing their state. This is a challenge, since light beams normally interpenetrate without interaction. In the approach of Tilman Pfau’s group interaction is achieved by exciting the photons in atomic gases by efficient absorption. Atoms in highly excited states interact with each other before the excitation and therefore the atom returns to a state with lower energy and light in form of a photon is emitted. In order to be scalable this process has to be perfectly controlled.
The scientists use both ultra cold clouds of atoms and for room temperature applications micro vapor glass cells, which they study parallel.  They work with a series of specialized laser systems. Close cooperations exist with theoretical physics and the electrical engineering departement.
The grant award is due to numerous scientific results that were published by Tilman Pfau and his team over the last years in international publications like Nature and Nature Physics and that attracted the interest of the public as well. Examples are are the first-time realization of a dipolar quantum gas and a Bose-Einstein condensate with chromium atoms, the discovery of giant molecules that consist of a highly excited Rydberg atom and an atom in the electronic ground state (http://www.uni-stuttgart.de/aktuelles/presse/2009/29.html), as well as  the latest research on giant molecules in a quantum superposition http://www.uni-stuttgart.de/aktuelles/presse/2010/126.html).

Further information:

Prof. Tilman Pfau, Universität Stuttgart, 5. Physikalisches Institut, Tel. ++49 (0)711/685-64820, e-mail: t.pfau@physik.uni-stuttgart.de


Prof. Tilman Pfau was born 1965 in Stuttgart. After his studies in Konstanz, Brighton, and Heidelberg he did his PhD at the University of Konstanz, where he habilitated in 1998. After his stay as a guest researcher at the Massachusetts Institute of Technology in the group of the later Nobel Prize winner Prof. Wolfgang Ketterle he accepted the call as a professor at the University of Stuttgart in 2000 and took over the direction of the newly founded 5th Physics Institute. Since 2005 he is the spokesman of the transregional collaborative research center SFB/TRR21, which is funded by the German Research Foundation (DFG). In cooperation with scientists at the universities in Stuttgart, Ulm, and Tübingen the focus of research within the SFB/TRR21 is on the control of quantum correlations in tailored matter. (photo: University of Stuttgart/Christa Müller)
ERC Advanced Investigator Grant SQUTEC „Spin Quantum Technologies“
(Prof. Jörg Wrachtrup)
Due to the advancing miniaturization of atomically structured solids as well as the integration of optical, mechanical and electronic components, quantum mechanical phenomena can be detected and used in a novel direction. The SQUTEC project will exploit this development in order to process and transfer information with extremely high speed and to design sensors of hitherto unequalled sensitivity. The key to success will be a material known for its special hardness and optical transparency: diamond. By precise doping with foreign substances, such as nitrogen for example, specific color centers can be produced. Physically speaking, those centers behave like embedded atoms: They are optically addressable and shielded from the environment by the diamond lattice. S atoms provide an excellent source for quantum technology. By using electron spins of a particular sort of diamond defects, quantum states can be prepared which are a prerequisite for data information transfer and processing. One particularity of this method is of great importance for practical applications: The diamond lattice protects the electron spins to such an extent that it allows the experiments to be performed at room temperature.
The ERC Grant will enable the realization of many technically demanding stages such as the positioning of nuclear impurities with nearly atomic accuracy. A purpose-built implanter will allow for the implementation of single atoms through extremely small apertures. With this technique, it will be possible to engineer large clusters of interacting impurities. Based on this principle, complex quantum states could be created and exploited for further applications.
Moreover, quantum arrays can be used for sensor applications since diamond defect centres have proven to be excellent sensors of magnetic fields. Built into nano probes, they permit detection of magnetic fields of single electron and nuclear spins with sub nanometer precision. This could be the first step to decoding structures of complex materials or molecules - such as proteins - with unprecedented accuracy. At the same time, diamonds of only few nanometers in size can be implanted into cells or tissue to serve as local probes for ph-value or the concentration of cell-damaging substances. Together with scientific work on the application of nanodiamonds as genetic or pharmaceutical ingredient carriers, the Grant allows for discovering new and attractive perspectives of usage.
The researchers at the 3 rd Institute of Physics of the University of Stuttgart are internationally renowned for their work on manipulation of single atoms in diamond and have achieved numerous publications notably in Nature, Nature Physics and Science. In 2009 they succeeded in synthesizing diamond out of methane plasma with purity 10.000 times higher than flawless diamonds (http://www.uni-stuttgart.de/aktuelles/presse/2009/26.html). A year ago, they achieved, in collaboration with the Ruhr Universität Bochum and colleagues from Austin/Texas, placement of two nitrogen atoms within only a few nanometers distance. Between the two atoms, they achieved quantum mechanical coupling through laser excitation thus setting a new milestone for quantum computing.
Professor Jörg Wrachtrup was born in 1961 in Herford and studied physics at the Freie Universität Berlin where he finished his doctorate in 1994 with his thesis on magnetic resonance in single molecules. As a postdoc, he continued his research at the Institute of Physics at the Technische Universität Chemnitz where he habilitated in 1998 working on ‘Optical Spectroscopy on Single Quantum Systems in Solid State’. He received offers for professorship from the universities in Hamburg, Göttingen, Leipzig and Stuttgart - the latter he accepted in January 2000. Since then he has directed the 3rd Physics Institute at the University of Stuttgart. (Foto: Privat)
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