2011/01/28 by Francisco Castilho Alcaraz, Miguel Ibanez Berganza, German Sierra · 1 citation
Physics and Astronomy · #cond-mat.stat-mech #hep-th #quant-ph
paper · pdf · doi:10.1103/physrevlett.106.201601
published as Phys.Rev.Lett.106:201601,2011 · 4 pages, 3 figures
arxiv created 2011/01/28 · arxiv updated 2011/05/23
In a quantum critical chain, the scaling regime of the energy and momentum of the ground state and low lying excitations are described by conformal field theory (CFT). The same holds true for the von Neumann and Renyi entropies of the ground state, which display a universal logarithmic behaviour depending on the central charge. In this letter we generalize this result to those excited states of the chain that correspond to primary fields in CFT. It is shown that the n-th Renyi entropy is related to a 2n-point correlator of primary fields. We verify this statement for the critical XX and XXZ chains. This result uncovers a new link between quantum information theory and CFT.