%0 Journal Article
%J Physical Review A
%D 2014
%T Long-range multipartite entanglement close to a first-order quantum phase transition
%A Stasińska, J.
%A Rogers, B.
%A M. Paternostro
%A De Chiara, G.
%A Sanpera, A.
%X We provide insight into the quantum correlations structure present in strongly correlated systems beyond the standard framework of bipartite entanglement. To this aim we first exploit rotationally invariant states as a test bed to detect genuine tripartite entanglement beyond the nearest neighbor in spin-1/2 models. Then we construct in a closed analytical form a family of entanglement witnesses which provides a sufficient condition to determine if a state of a many-body system formed by an arbitrary number of spin-1/2 particles possesses genuine tripartite entanglement, independently of the details of the model. We illustrate our method by analyzing in detail the anisotropic XXZ spin chain close to its phase transitions, where we demonstrate the presence of long-range multipartite entanglement near the critical point and the breaking of the symmetries associated with the quantum phase transition.
%B Physical Review A
%V 89
%8 3/2014
%N 3
%! Phys. Rev. A
%R 10.1103/PhysRevA.89.032330
%0 Journal Article
%J ArXiv e-prints
%D 2011
%T A continuous-variable formalism for the Faraday atom-light interface
%A Stasińska, J.
%A Paganelli, Simone
%A Rodó, C.
%A Sanpera, A.
%X Quantum interfaces between polarized atomic ensembles and coherent states of light, applied recently to manipulate bipartite and multipartite entanglement, are revisited by means of a continuous-variable formalism. The explicit use of the continuous-variable formalism facilitates significantly the analysis of entanglement between different modes, reducing it to the study of the properties of a final covariance matrix which can be found analytically. Furthermore, it allows to study matter-light interfaces for mixed states, adapting the formalism to the experimental situations in which the initial prepared Gaussian states are, unavoidably, affected by a certain amount of noise. A multipartite scenario, leading to the generation of macroscopic cluster states is presented and analyzed in detail within this formalism.
%B ArXiv e-prints
%G eng
%U http://arxiv.org/abs/1007.0403