Phys. Rev. Lett. 102, 017204 (2009) [4 pages]Lieb-Robinson Bounds and the Speed of Light from Topological OrderReceived 18 August 2008; revised 29 October 2008; published 5 January 2009 We apply the Lieb-Robinson bounds technique to find the maximum speed of interaction in a spin model with topological order whose low-energy effective theory describes light [see X.-G. Wen Phys. Rev. B 68 115413 (2003)]. The maximum speed of interactions in two dimensions is bounded from above by less than e times the speed of emerging light, giving a strong indication that light is indeed the maximum speed of interactions. This result does not rely on mean field theoretic methods. In higher spatial dimensions, the Lieb-Robinson speed is conjectured to increase linearly with the dimension itself. The implications for the horizon problem in cosmology are discussed. © 2009 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.102.017204
DOI:
10.1103/PhysRevLett.102.017204
PACS:
75.10.Jm, 05.50.+q, 11.15.−q, 71.10.−w
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