Erlangen 2018 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 10: Quantum Gases (Bosons) I

Q 10.8: Vortrag

Montag, 5. März 2018, 12:15–12:30, K 2.020

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.