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Supersonic propagation in long-range lattice models

Event Details

Event Dates: 

Monday, August 25, 2014 - 3:00pm

Seminar Location: 

  • JILA X317

Speaker Name(s): 

Dr. Michael Kastner

Speaker Affiliation(s): 

National Institute for Theoretical Physics, South Africa
Seminar Type/Subject

Scientific Seminar Type: 

  • JILA Public Seminar

Event Details & Abstract: 

A striking feature of the nonequilibrium dynamics of long-range interacting lattice systems is explored, namely the absence of a finite group velocity for the spreading of correlations or information. We study classical and quantum lattice models with long-ranged interactions decaying asymptotically for large distances like a power law. For exponents larger than the lattice dimensionality, a Lieb-Robinson-type bound effectively restricts the spreading of correlations to a causal region, but allows supersonic propagation. For any exponents smaller than the lattice dimension, we construct Hamiltonians giving rise to quantum channels with capacities not restricted to a causal region. Numerical and analytical results reveal the presence of an approximate sound cone for large exponents, and supersonic propagation for small ones. The results should be relevant for the understanding of equilibration and thermalisation in long-range interacting quantum systems. Finally, experimental implementations are briefly discussed.