title: Quantum metrology. Fisher information and entanglement of non-Gaussian spin states.
abstract: Entanglement is the key quantum resource for improving measurement sensitivity beyond classical limits. However, the production of entanglement in mesoscopic atomic systems has been limited to squeezed states, described by Gaussian statistics. Here, we report on the creation and characterization of non-Gaussian many-body entangled states. We develop a general method to extract the Fisher information, which reveals that the quantum dynamics of a classically unstable system creates quantum states that are not spin squeezed but nevertheless entangled. The extracted Fisher information quantifies metrologically useful entanglement, which we confirm by Bayesian phase estimation with sub-shot-noise sensitivity. These methods are scalable to large particle numbers and applicable directly to other quantum systems.
authors: Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany. fisherinformation@matterwave.de.
authors: Helmut
authors: H
authors: Strobel
authors: Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
authors: Wolfgang
authors: W
authors: Muessel
authors: Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
authors: Daniel
authors: D
authors: Linnemann
authors: Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
authors: Tilman
authors: T
authors: Zibold
authors: Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
authors: David B
authors: DB
authors: Hume
authors: QSTAR (Quantum Science and Technology in Arcetri), INO-CNR (Istituto Nazionale di Ottica-Consiglio Nazionale delle Ricerche), and LENS (European Laboratory for Nonlinear Spectroscopy), Largo Enrico Fermi 2, 50125 Firenze, Italy.
authors: Luca
authors: L
authors: Pezzè
authors: QSTAR (Quantum Science and Technology in Arcetri), INO-CNR (Istituto Nazionale di Ottica-Consiglio Nazionale delle Ricerche), and LENS (European Laboratory for Nonlinear Spectroscopy), Largo Enrico Fermi 2, 50125 Firenze, Italy.
authors: Augusto
authors: A
authors: Smerzi
authors: Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
authors: Markus K
authors: MK
authors: Oberthaler