General Information

Collaborative Research Center 631:
Solid-State Based Quantum Information Processing: Physical Concepts and Materials Aspects

The Sonderforschungsbereich 631 (Collaborative Research Centre 631) was installed by the Deutsche Forschungsgemeinschaft (German Science Foundation, DFG) effective in July 1, 2003.  In May 2007, the Senatsausschuss für die Angelegenheiten der Sonderforschungsbereiche of the DFG has granted the second four-year funding period. Within 18 research projects subdivided into three research areas, groups from the Bavarian Academy of Sciences, the Technical University of Munich, the Ludwig-Maximilians-University, the Max-Planck-Institute for Quantum Optics, as well as the University of Regensburg and the University of Augsburg are collaborating. In addition to the 35 principle investigators, more than 60 PhD and diploma students as well as a large number of guests are involved in the research activities.  Spokesman of SFB 631 is Rudolf Gross of Walther-Meißner-Institute, BAdW, and Chair for Technical Physics (E23), TU Munich.

The Collaborative Research Center 631 studies the physical concepts, materials aspects, and technological foundations of solid-state quantum information processing (SQIP). This interdisciplinary research field has the potential to revolutionize many areas of science and technology. It deals with the coherent dynamics of solid-state quantum systems and has the daring vision to be able to process and communicate information on the basis of quantum mechanical principles. To realize this vision, the SFB 631 aims at the clarificationof the key physical questions and technological problems related to SQIP:

  • How can we realize solid-state quantum bits (qubits – the quantum mechanical generalizations of the classical bits in classical information processing) with sufficiently long decoherence time?
  • Which degrees of freedom in solid state systems are most suitable for the implementation of solid state based quantum bits?
  • How can we effectively control, manipulate and read-out these qubits?
  • What are the optimum concepts for controlling decoherence?
  • How can we couple solid-state qubits and scale individual solid-state quantum bits to complex systems?
  • Which are the key materials aspects and technological problems to be solved for the successful implementation of SQIP?
  • How can we transfer qubit states to photons to generate an interface between solid-state quantum processors and quantum communication systems?

To clarify these questions in a fundamental and comprehensive way, the SFB 631 joins research activities
from quantum information theory, experimental and theoretical solid-state physics, quantum optics, materials science, nanotechnology and electrical engineering. The objective is to achieve a profound understanding of the physics, technology, and materials aspects of SQIP by applying state of the art experimental and theoretical methods in a coordinated interdisciplinary research effort. Particular goals are

  • to design and implement solid-state qubits with long decoherence time,
  • to learn how to efficiently control, manipulate and read-out the qubits,
  • to couple them to complex systems as well as
  • to develop theoretical tools for modeling the dynamics of driven, damped qubits in different experimental systems.

In the long term, the quantum properties of the solid-state qubits, namely the possibility to form superpositions of different quantum states and to entangle several qubits, form the basis for new, completely secure communication methods like quantum cryptography and quantum teleportation. SQIP also holds the promise of immense computing power far beyond the capabilities of classical computers. Finally, it is closely linked to a variety of emerging quantum technologies such as quantum sensors, quantum standards, or quantum measuring systems.

What is a Collaborative Research Center?

Collaborative Research Centres are long-term university research centres in which scientists and researchers work together within a cross-disciplinary research programme. They are installed by the German Science Foundation with the purpose to create core research areas at universities by establishing temporary centres of excellence, to promote interdisciplinary cooperation and to advance young researchers. As a rule the funding duration is up to 12 years with a single funding period running for four years. Funding includes staff funding (including the head of an independent Junior Research Group), funding for scientific instrumentation, consumables, travel, publication allowance, funding for colloquia and visiting researchers.