Berlin 2018 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 35: Nonequilibrium Quantum Many-Body Systems I (joint session TT/DY)
DY 35.12: Vortrag
Mittwoch, 14. März 2018, 12:45–13:00, H 3010
Reconstructing quantum states of cold atomic quantum simulators from non-equilibrium dynamics — •Marek Gluza1, Thomas Schweigler2, Bernhard Rauer2, Christian Krumnow1, Joerg Schmiedmayer2, and Jens Eisert1 — 1Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195 Berlin, Germany — 2Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria
Systems of ultra-cold atoms on atom chips provide an architecture to probe aspects of out-of-equilibrium quantum many-body physics including equilibration, thermalization and pre-thermalization. We present a novel tomographic reconstruction method for these quantum simulators allowing to access the expectation value of quadrature operators which are inaccessible from direct measurements but capture crucial characteristics of the elementary excitations of cold atomic systems. Specifically, we use interferometric data of non-equilibrium phase fluctuations to reconstruct the covariance matrix -- including density fluctuations -- of eigenmodes of the corresponding mean-field models. Experimentally, we observe quench dynamics in the non-interacting regime of particles in harmonic or box potentials. Formally, we use that one can efficiently keep track of the evolution and employ signal processing and semi-definite programming to perform a reliable reconstruction of covariance matrices. This method opens a new window into the study of dynamical quantum simulators -- an insight that we exploit and discuss at the hand of several examples, including Gaussifying quantum many-body dynamics.