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Light-cone-like spreading of correlations in a quantum many-body system

Cheneau, Marc and Barmettler, Peter and Poletti, Dario and Endres, Manuel and Schauß, Peter and Fukuhara, Takeshi and Gross, Christian and Bloch, Immanuel and Kollath, Corinna and Kuhr, Stefan (2012) Light-cone-like spreading of correlations in a quantum many-body system. Nature, 481 (7382). pp. 484-487. ISSN 0028-0836.

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In relativistic quantum field theory, information propagation is bounded by the speed of light. No such limit exists in the non-relativistic case, although in real physical systems, short-range interactions may be expected to restrict the propagation of information to finite velocities. The question of how fast correlations can spread in quantum many-body systems has been long studied. The existence of a maximal velocity, known as the Lieb–Robinson bound, has been shown theoretically to exist in several interacting many-body systems (for example, spins on a lattice)—such systems can be regarded as exhibiting 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 not been observed experimentally. Here we report 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 reveal how quasiparticle pairs transport correlations with a finite velocity across the system, resulting in an effective light cone for the quantum dynamics. Our results open perspectives for understanding the relaxation of closed quantum systems far from equilibrium, and for engineering the efficient quantum channels necessary for fast quantum computations.

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Endres, Manuel0000-0002-4461-224X
Additional Information:© 2012 Macmillan Publishers Limited. Received 06 October 2011. Accepted 01 December 2011. Published online 25 January 2012. We thank C. Weitenberg and J. F. Sherson for their contribution to the design and construction of the apparatus. We also thank D. Baeriswyl, T. Giamarchi, V. Gritsev and S. Huber for discussions. C.K. acknowledges previous collaboration on a related subject with A. Läuchli. We acknowledge funding by MPG, DFG, EU (NAMEQUAM, AQUTE, Marie Curie Fellowship to M.C.), JSPS (Postdoctoral Fellowship for Research Abroad to T.F.), ‘Triangle de la physique’, ANR (FAMOUS) and SNSF (under division II and MaNEP). Financial support for the computer cluster on which the calculations were performed was provided by the Fondation Ernst et Lucie Schmidheiny. Author Contributions: M.C. performed the experiment. P.B. performed the numerical simulations. P.B., D.P. and C.K. developed the analytical model. M.C. and P.B. carried out the data analysis. All authors contributed to designing the study, to interpreting the data and to writing the manuscript. The authors declare no competing financial interests.
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Deutsche Forschungsgemeinschaft (DFG)UNSPECIFIED
European Research Council (ERC)UNSPECIFIED
Marie Curie FellowshipUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)UNSPECIFIED
Agence Nationale pour la Recherche (ANR)UNSPECIFIED
Swiss National Science Foundation (SNSF)UNSPECIFIED
Fondation Ernst et Lucie SchmidheinyUNSPECIFIED
Issue or Number:7382
Record Number:CaltechAUTHORS:20160526-151342040
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Official Citation:Light-cone-like spreading of correlations in a quantum many-body system Marc Cheneau, Peter Barmettler, Dario Poletti, Manuel Endres, Peter Schauß, Takeshi Fukuhara, Christian Gross, Immanuel Bloch, Corinna Kollath & Stefan Kuhr Nature 481, 484–487 (26 January 2012) doi:10.1038/nature10748
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67409
Deposited By: Ruth Sustaita
Deposited On:27 May 2016 19:07
Last Modified:30 Oct 2019 19:32

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