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Published on: May 30, 2014
Limits to Velocity of Signal Propagation in Many-Body Systems: A Quantum Information Perspective
Piotr Wysocki1, Jan Chwedeńczuk1
1University of Warsaw, Faculty of Physics, ulica Pasteura 5, 02-093 Warszawa, Poland.
Abstract:
The Lieb-Robinson bound (LRB) states that the range and strength of interactions between the constituents of a complex many-body system impose upper limits to how fast the signal can propagate. It manifests in a light conelike growth of correlation function connecting two distant subsystems. Here, we employ the techniques of quantum information to demonstrate that the LRB can be determined from local measurements performed on a single qubit that is connected to a many-body system. This formulation provides an operational recipe for estimating the LRB in complex systems, replacing the measurement of the correlation function with simple single-particle manipulations. We demonstrate the potency of this approach by deriving the upper limit to the speed of signal propagation in the XY spin chain.
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