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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik

MP 1: Quanten-Information I

MP 1.1: Vortrag

Montag, 17. März 2014, 15:00–15:20, SPA SR125

Emergence of coherence and the dynamics of quantum phase transitions — Simon Braun^1,2, •Mathis Friesdorf³, Sean Hodgman^1,2, Michael Schreiber^1,2, Jens Philipp Ronzheimer^1,2, Arnau Riera^3,4, Marco del Rey⁵, Immanuel Bloch^1,2, Jens Eisert³, and Ulrich Schneider^1,2 — ¹Max-Planck-Institut für Quantenoptik, Garching, Germany — ²Ludwig-Maximilians-Universität München, Munich, Germany — ³Freie Universität Berlin, Berlin, Germany — ⁴Max Planck Institute for Gravitational Physics, Potsdam-Golm, Germany — ⁵Instituto de Fisica Fundamental, CSIC, Madrid, Spain

We investigate the dynamical emergence of coherence when crossing the Mott to superfluid quantum phase transition in the precisely controllable setup of ultracold atoms, experimentally addressing long-standing questions on the dynamics of quantum phase transitions. For one-dimensional systems, we find perfect agreement between experimental observations and numerical simulations of homogeneous systems, thus performing a certified quantum simulation. For intermediate quench velocities, we observe a power-law behaviour of the coherence length, reminiscent of the Kibble-Zurek mechanism. Contrary to what the latter suggests, we find a complex behaviour, yielding exponents that strongly depend on the final interaction strength in the superfluid. By using the full power of the quantum simulation, we also explore the emergence of coherence in higher dimensions as well as for negative temperatures. We connect our findings with insights into the propagation of quasiparticles and close-to-adiabatic quantum evolutions.