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Title: Witnessing nonclassical multipartite states

Abstract

We investigate a witness for nonclassical multipartite states based on their disturbance under local measurements. The witness operator provides a sufficient condition for nonclassicality that coincides with a nonvanishing global quantum discord, but it does not demand an extremization procedure. Moreover, for the case of Z{sub 2}-symmetric systems, we rewrite the witness in terms of correlation functions so that classicality is found to necessarily require either vanishing magnetization in the invariant axis or isotropy of the two-point function in the transverse spin plane. We illustrate our results in quantum spin chains, where a characterization of factorized ground states (with spontaneously broken Z{sub 2} symmetry) is achieved. As a by-product, the witness is also shown to indicate a second-order quantum phase transitions, which is illustrated for both the XY and the Ashkin-Teller spin chains.

Authors:
; ; ;  [1]
  1. Instituto de Fisica, Universidade Federal Fluminense, Avenida General Milton Tavares de Souza s/n, Gragoata, 24210-346 Niteroi, Rio de Janeiro (Brazil)
Publication Date:
OSTI Identifier:
22080339
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 84; Journal Issue: 4; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CORRELATION FUNCTIONS; GROUND STATES; ISOTROPY; MAGNETIZATION; PHASE TRANSFORMATIONS; SPIN; SYMMETRY

Citation Formats

Saguia, A, Rulli, C C, Oliveira, Thiago R. de, and Sarandy, M S. Witnessing nonclassical multipartite states. United States: N. p., 2011. Web. doi:10.1103/PHYSREVA.84.042123.
Saguia, A, Rulli, C C, Oliveira, Thiago R. de, & Sarandy, M S. Witnessing nonclassical multipartite states. United States. https://doi.org/10.1103/PHYSREVA.84.042123
Saguia, A, Rulli, C C, Oliveira, Thiago R. de, and Sarandy, M S. Sat . "Witnessing nonclassical multipartite states". United States. https://doi.org/10.1103/PHYSREVA.84.042123.
@article{osti_22080339,
title = {Witnessing nonclassical multipartite states},
author = {Saguia, A and Rulli, C C and Oliveira, Thiago R. de and Sarandy, M S},
abstractNote = {We investigate a witness for nonclassical multipartite states based on their disturbance under local measurements. The witness operator provides a sufficient condition for nonclassicality that coincides with a nonvanishing global quantum discord, but it does not demand an extremization procedure. Moreover, for the case of Z{sub 2}-symmetric systems, we rewrite the witness in terms of correlation functions so that classicality is found to necessarily require either vanishing magnetization in the invariant axis or isotropy of the two-point function in the transverse spin plane. We illustrate our results in quantum spin chains, where a characterization of factorized ground states (with spontaneously broken Z{sub 2} symmetry) is achieved. As a by-product, the witness is also shown to indicate a second-order quantum phase transitions, which is illustrated for both the XY and the Ashkin-Teller spin chains.},
doi = {10.1103/PHYSREVA.84.042123},
url = {https://www.osti.gov/biblio/22080339}, journal = {Physical Review. A},
issn = {1050-2947},
number = 4,
volume = 84,
place = {United States},
year = {2011},
month = {10}
}