Entanglement observables and witnesses for interacting quantum spin systems

L.-A. Wu, S. Bandyopadhyay, M. S. Sarandy, and D. A. Lidar

Phys. Rev. A 72, 032309 – Published 7 September 2005

Abstract

We discuss the detection of entanglement in interacting quantum spin systems. First, thermodynamic Hamiltonian-based witnesses are computed for a general class of one-dimensional spin- $1 ∕ 2$ models. Second, we introduce optimal bipartite entanglement observables. We show that a bipartite entanglement measure can generally be associated with a set of independent two-body spin observables whose expectation values can be used to witness entanglement. The number of necessary observables is ruled by the symmetries of the model. Illustrative examples are presented.

Received 14 December 2004

DOI:https://doi.org/10.1103/PhysRevA.72.032309

Authors & Affiliations

L.-A. Wu, S. Bandyopadhyay^*, M. S. Sarandy, and D. A. Lidar^†

Chemical Physics Theory Group, Chemistry Department, and Center for Quantum Information and Quantum Control, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada

^*Present address: Institute for Quantum Information Science, University of Calgary, Calgary, AB, T2N 1N4 Canada.
^†Present address: Departments of Chemistry and Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA

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Vol. 72, Iss. 3 — September 2005

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