Browsing by Author "Halimeh, Jad C."

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    Prethermalization and persistent order in the absence of a thermal phase transition
    (American Physical Society, 2017) Halimeh, Jad C.; Zauner-Stauber, Valentin; McCulloch, Ian P.; De Vega, Ines; Schollwock, Ulrich; Kastner, Michael
    We numerically study the dynamics after a parameter quench in the one-dimensional transverse-field Ising model with long-range interactions (∝1/rα with distance r), for finite chains and also directly in the thermodynamic limit. In nonequilibrium, i.e., before the system settles into a thermal state, we find a long-lived regime that is characterized by a prethermal value of the magnetization, which in general differs from its thermal value. We find that the ferromagnetic phase is stabilized dynamically: as a function of the quench parameter, the prethermal magnetization shows a transition between a symmetry-broken and a symmetric phase, even for those values of α for which no finite-temperature transition occurs in equilibrium. The dynamical critical point is shifted with respect to the equilibrium one, and the shift is found to depend on α as well as on the quench parameters.
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    Universal equilibrium scaling functions at short times after a quench
    (American Physical Society, 2017) Karl, Markus; Cakir, Halil; Halimeh, Jad C.; Oberthaler, Markus K.; Kastner, Michael; Gasenzer, Thomas
    By analyzing spin-spin correlation functions at relatively short distances,we showthat equilibrium near-critical properties can be extracted at short times after quenches into the vicinity of a quantum critical point. The time scales after which equilibrium properties can be extracted are sufficiently short so that the proposed scheme should be viable for quantum simulators of spin models based on ultracold atoms or trapped ions. Our results, analytic as well as numeric, are for one-dimensional spin models, either integrable or nonintegrable, but we expect our conclusions to be valid in higher dimensions as well.