Spin squeezed states in atomic systems have already been generated and detected in various different physical systems employing different methods. We report on the generation of spin squeezed states building on the quantum dynamics close to an unstable fixed point of the underlying classical dynamics. This new method allows the generation of 6dB squeezed states on short time scale. Since the squeezed states can be described as slightly distorted gaussian states the observation of variances is sufficient to verify the presence of entanglement.
Our new way of squeezing generation also allows the exploration of transient states towards the generation of cat states. We will report on our results preparing and characterizing these transient non-gaussian states. They reveal variances which are larger than the classical shot noise limit thus suppression of fluctuations cannot be employed as an entanglement witness. We therefore developed a novel method for detecting the presence of entanglement by extracting from the experimentally detected distribution functions a bound of the Fisher information present in the system. With that we confirm that the entanglement is still present although the states are not spin squeezed. Furthermore interferometry beyond classical limits with these states is demonstrated which can be achieved by maximum likelihood estimation of the interferometric phase .
We will also present a general approach which allows the upscaling of squeezed states to large atom numbers by employing the concept - divide and conquer. We explicitly demonstrate 5dB squeezing for more than 13000 particles. We use this resource and combined this with swapping the squeezing to magnetically sensitive states for demonstration of quantum enhanced magnetometry with high spatial resolution .
I will also give a short overview of the current topics we are investigating ranging from probing quantum critical points with quenches, Poincare Birkhoff scenario for many particle systems and the implementation of SU(1,1) interferometry.
 H. Strobel, W. Muessel, D. Linnemann, T. Zibold, D.B. Hume, L. Pezzè, A. Smerzi, M.K. Oberthaler, Science 345, 424 (2014).
 W. Muessel, H. Strobel, D. Linnemann, D.B. Hume, M.K. Oberthaler, Phys. Rev. Lett. August (2014).
May 3rd 1968 born in Innsbruck; Austria:
Parents: Gerda Oberthaler, Kurt Oberthaler
1986-1990 Student of Physics at the University Innsbruck
1990-1992 Diploma thesis at the Department of Experimental Physics in Innsbruck:
‘Characterization and temporal compression of ultrashort laser pulses’
Supervisor: Doz. Ralph Höpfel; (finished with honors)
1993- 1997 Ph.D. thesis at the Department of Experimental Physics in Innsbruck:
‘Waves in periodic media’;
Supervisor: Prof. Anton Zeilinger; (finished with honors)
1997 -1999 Research fellow at the University of Oxford, Clarendon Laboratory in the group of Prof. Keith Burnett and Dr. Christopher Foot
2000 - 2003 Award of the Emmy Noether fellowship;
Leader of an independent research group at the Optik-Zentrum Konstanz.
Since 2003 Professor position at the University of Heidelberg
2008 Landesforschungspreis for fundamental research Baden-Württemberg