Hannover 2013 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 18: Quantum gases: Mixtures, spinor gases, disorder effects
Q 18.5: Talk
Monday, March 18, 2013, 17:30–17:45, E 001
Detection of Fisher information for mesoscopic quantum states — •Helmut Strobel1, Wolfgang Muessel1, Tilman Zibold1, Luca Pezze2, Eike Nicklas1, Jiri Tomkovic1, Ion Stroescu1, Maxime Joos1, Daniel Linnemann1, David B. Hume1, Augusto Smerzi2, and Markus K. Oberthaler1 — 1Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany — 2INO-CNR and LENS, Largo Fermi 6, I-50125 Firenze, Italy
A very general classification of quantum states is the quantum Fisher information. It can be calculated from the density matrix which is experimentally accessible by state tomography. For a mesoscopic number of particles full state tomography with the necessary precision cannot be implemented in our system. Instead, we use the fact that the Fisher information is the key parameter quantifying possible sensitivity beyond the standard quantum limit in a phase estimation protocol.
We will present the realization of collective states of binary Bose-Einstein condensates with about 350 atoms and the analysis of their interferometric performance which gives a lower bound on the Fisher information. Our method is able to show that the Fisher information surpasses the shot-noise limit in a regime where no spin squeezing is present and thus reveals multiparticle entanglement.