Quantum Inf Process DOI 10.1007/s11128-015-1216-5 Nonlocality in pure and mixed n-qubit X states J. Batle 1 · C. H. Raymond Ooi 2 · Ahmed Farouk 3 · S. Abdalla 4 Received: 13 October 2015 / Accepted: 8 December 2015 © Springer Science+Business Media New York 2015 Abstract Nonlocality for general multiqubit X states is studied in detail. Pure and mixed states are analyzed as far as their maximum amount of nonlocality is concerned, and analytic results are obtained for important families of these states. The particular form of nonzero diagonal and antidiagonal matrix elements makes the corresponding study easy enough to obtain exact results. We also provide a numerical recipe to randomly generate an important family of X states endowed with a given degree of mixture. Keywords Nonolocality · X-Qubit states · Multipartite correlations 1 Introduction Quantum correlations lie at the heart of quantum information theory. They are respon- sible for some tasks that possess no classical counterpart. Among those correlations, entanglement is perhaps one of the most fundamental and non-classical features exhib- ited by quantum systems [1–10]. Other measures have been introduced in the literature that grasp features that are not captured by entanglement, like the maximum violation B J. Batle jbv276@uib.es 1 Departament de Física, Universitat de les Illes Balears, 07122 Palma de Mallorca, Balearic Islands, Spain 2 Department of Physics, University of Malaya, 50603 Kuala Lumpur, Malaysia 3 Information Technology Department, Al-Zahra College for Women, P.O.Box 3365, Muscat, Oman 4 Department of Physics, Faculty of Science, King Abdulaziz University Jeddah, P.O. Box 80203, Jeddah 21589, Saudi Arabia 123