## Research Profiles

The doctorate programme is initiated by a nucleus of four research groups in Munich:

Prof.
Dr S. J. Glaser (chairman)

Quantum control, NMR

Dept. Chemistry
Technical University of Munich (TUM)

e-mail: glaser@ch.tum.de

Prof. Dr H. Weinfurter

Quantum communication

Section of Physics
Ludwig Maximilians University of Munich (LMU)

e-mail: harald.weinfurter@physik.uni-muenchen.de

Prof. Dr J. I. Cirac

Quantum information

Director of the Theory Group
Max-Planck Institute of Quantum Optics (MPQ)

e-mail: ignacio.cirac@mpq.mpg.de

Prof. Dr G. Rempe

Experimental quantum dynamics

Director of the Quantum Dynamics Group
Max-Planck Institute of Quantum Optics (MPQ)

e-mail: gerhard.rempe@mpq.mpg.de

The doctorate programme is in close exchange with the following research networks:

- by DFG: solid-state-based quantum information (DFG initiative 631)
- by EU: QGATES, QUPRODIS, RAMBOCQ, RESQ, SECOQC, TOPQUIP; SCALA, QAP

Profile of Prof.
Dr S. J. Glaser's group

glaser@ch.tum.de

- the first 5-qubit quantum computer by tailored chemical synthesis,
- the first scalable implementation of a Deusch-Jozsa algorithm on spin ensembles,
- time-optimal and decoherence-minimising controls of spin systems,
- a general gradient-flow-based algorithm for maximising quantum quality functions (e.g. for coherence transfer in ensemble spectroscopy).

- S.J. Glaser, T. Schulte-Herbrüggen, M. Sieveking, O. Schedletzky, N.C. Nielsen, O.W. Sørensen, and C. Griesinger, "Unitary Control in Quantum Ensembles: Maximising Signal Intensity in Coherent Spectroscopy" Science 280, 421 (1998).
- R. Marx, A.F. Fahmy, J.M. Myers, W. Bermel, and S.J. Glaser, "Approaching Five-Bit NMR Quantum Computing", Phys. Rev. A 62, 012310 (2000).
- N. Khaneja, R. Brockett, and S.J. Glaser, "Time-Optimal Control in Spin Systems", Phys. Rev. A 63, 032308 (2001).
- N. Khaneja, B. Luy, and S.J. Glaser, "Boundary of Quantum Evolution under Decoherence", Proc. Natl. Acad. Sci. USA 100, 13162 (2003).
- N. Khaneja, T. Reiss, C. Kehlet, T. Schulte-Herbrüggen, and S.J. Glaser, "Optimal Control of Coupled Spin Dynamics: Design of NMR Pulse Sequences by Gradient Ascent Algorithms" J. Magn. Reson. 172, 296 (2005).

Profile of Prof.
Dr H. Weinfurter's group

harald.weinfurter@physik.uni-muenchen.de

The research group uses experience of fundamental quantum experiments for novel developments in the field of quantum communication and quantum information. Major achievements have been

- the development of prototypes of quantum cryptography (designed to be close to series production),
- multi-photon entanglement,
- operations with linear optical quantum gates,
- experimental multi-party quantum communication.

See the following key papers:

- H. Weinfurter, "Experimental Bell-State Analysis" Europhys. Lett. 25, 559 (1994).
- D. Bowmeester, J.W. Pan, K. Mattle, M. Eibl, H. Weinfurter, and A. Zeilinger, "Experimental Quantum Teleportation", Nature 390, 576 (1997).
- C. Kurtsiefer, S. Mayer, P. Zarda, and H. Weinfurter, "A Stable Solid-State Source of Single Photons", Phys. Rev. Lett. 85, 290 (2000).
- C. Kurtsiefer, P. Zarda, M. Halder, H. Weinfurter, P.M. Gorman, P.R. Tapster, and J.G. Rarity, "A Step towards Global Key Distribution", Nature 419, 450 (2002).
- M. Eibl, S. Gaertner, M. Bourennane, C. Kurtsiefer, M. Zukowski, and H. Weinfurter, "Experimental Observation of Four-Photon Entanglement for Parametric Down-Conversion" Phys. Rev. Lett. 90, 200403 (2003).

Profile of Prof.
Dr J. I. Cirac's group

ignacio.cirac@mpq.mpg.de

The research group develops physical models for quantum information processing and, more general, for quantum information theory. Major achievements have been

- the first implementations of ion-trap quantum computing,
- realisation of quantum communication systems;
- significant contributions to the theory of entanglement
- and the theory of quantum repeaters.

- J.I. Cirac and P. Zoller, "Quantum computations with Cold Trapped Ions" Phys. Rev. Lett. 74, 4091 (1995).
- S. van Enk, J.I. Cirac, and P. Zoller, "Photonic channels for Quantum Communication", Science 279, 205 (1998).
- L.M. Duan, J.I. Cirac, and P. Zoller, "Geometric Manipulation of Trapped Ions for Quantum Computation", Science 292, 1695 (2001).
- J.I. Cirac and P. Zoller, "A Scalable Quantum Computer with Ions in an Array of Microtraps", Nature 404, 579 (2000).
- L.M. Duan, M. Lukin, J.I. Cirac, and P. Zoller, "Long-Distance Quantum Communication with Atomic Ensembles and Linear Optics" Nature 414, 413 (2001).

Profile of Prof. Dr
G. Rempe's group

gerhard.rempe@mpq.mpg.de

- observation of single atoms in an optical cavity in realtime,
- development of cavity cooling to trap single atoms in a cavity
- observation of the vacuum-Rabi splitting of a bound atom-cavity system,
- nano-positioning of single atoms in a micro-cavity,
- deterministic generation of single photons with a reversible process,
- observation of time-resolved interference of single photons,
- association of molecules from an atomic Bose-Einstein, condensate,
- guiding and trapping of slow dipolar molecules with electric fields.

- P.W.H. Pinkse, T. Fischer, P. Maunz, and G. Rempe, "Trapping an Atom with Single Photons" Nature 404, 365 (2000).
- M. Hennrich, T. Legero, A. Kuhn, and G. Rempe, "Vacuum-Stimulated Raman Scattering Based on Adiabatic Passage in a High-finesse Optical Cavity", Phys. Rev. Lett. 85, 4872 (2000).
- A. Kuhn, M. Hennrich, and G. Rempe, "Deterministic Single-Photon Source for Distributed Quantum Networking", Phys. Rev. Lett. 89, 067901 (2002).
- T. Legero, T. Wilk, M. Hennrich, G. Rempe, and A. Kuhn, "Quantum Beat of Two Single Photons" Phys. Rev. Lett. 93, 070503 (2004).
- P. Maunz, T. Puppe, I. Schuster, N. Syassen, P.W.H. Pinske, and G. Rempe, "Cavity Cooling of Single Atoms", Nature 428, 50 (2004).
- P. Maunz, T. Puppe, I. Schuster, N. Syassen, P.W.H. Pinkse, and G. Rempe, "Normal-mode spectroscopy of a single bound atom-cavity system",Phys. Rev. Lett. 94, 033002 (2005).