Stuttgart 2012 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 43: Ultra-cold atoms, ions and BEC II
Q 43.5: Talk
Thursday, March 15, 2012, 11:30–11:45, V47.02
Light-cone-like spreading of correlations in a quantum many-body system — Marc Cheneau1, Peter Barmettler2, Dario Poletti2, Manuel Endres1, •Peter Schauß1, Takeshi Fukuhara1, Christian Gross1, Immanuel Bloch1,3, Corinna Kollath2,4, and Stefan Kuhr1,5 — 1Max-Planck-Institut für Quantenoptik, 85748 Garching — 2Département de physique théorique, Université de Genève, 1211 Geneva, Switzerland — 3Ludwig-Maximilians-Universität, 80799 München — 4Centre de physique théorique, École Polytechnique, CNRS, 91128 Palaiseau, France — 5University of Strathclyde, SUPA, Glasgow G4 0NG, UK
How fast can correlations spread in a quantum many-body system? Based on the seminal work by Lieb and Robinson, it has recently been shown that several interacting many-body systems exhibit an effective light cone that bounds the propagation speed of correlations. The existence of such a "speed of light" has profound implications for condensed matter physics and quantum information, but has never been observed experimentally. In this talk I will report on the time-resolved detection of propagating correlations in an interacting quantum many-body system. By quenching a one-dimensional quantum gas in an optical lattice, we have revealed how quasiparticle pairs transport correlations with a finite velocity across the system, resulting in an effective light cone for the quantum dynamics. These results open important perspectives for understanding relaxation of closed quantum systems far from equilibrium as well as for engineering efficient quantum channels necessary for fast quantum computations.