Speaker
Tamas Palmai
(SISSA, INFN TS)
Description
We study the excited state subsystem purity (equivalent to 2nd Renyi entropy) as a measure of entanglement in 1+1d conformal field theories. In order to access the highly excited states we generalize the replica approach and develop a systematic framework to treat arbitrary states (in particular descendants) by means of novel CFT techniques including transformation of descendant fields under conformal mappings and exact evaluation of descendant n-point functions. By examining a number of individual states in the critical Ising and three-state Potts models we uncover a new interesting regime of the subsystem purity as a function of the relative subsystem size: when the subsystems are comparable purity decays exponentially with an exponent depending only on the excitation energy and in a nonlinear way. For the Renyi entropy this translates as a quasi thermodynamic entropy, that is extensive but obeys a nonlinear 1st law analog. As an additional application of the present framework we show preliminary results for ground and excited state Renyi entropies in the massive Ising model using a truncated conformal space approach.
arXiv:1406.3182 [hep-th]
Primary author
Tamas Palmai
(SISSA, INFN TS)
