We analyse the minimum quantum resources needed to realise strong non-locality, as exemplified e.g. by the classical GHZ construction. It was already known that no two-qubit system, with any finite number of local measurements, can realise strong non-locality. For three-qubit systems, we show that strong non-locality can only be realised in the GHZ SLOCC class, and with equatorial measurements. However, we show that in this class there is an infinite family of states which are pairwise non LU-equivalent that realise strong non-locality with finitely many measurements. These states have decreasing entanglement between one qubit and the other two, necessitating an increasing number of local measurements on the latter.
@InProceedings{abramsky_et_al:LIPIcs.TQC.2017.9, author = {Abramsky, Samson and Barbosa, Rui Soares and Car\`{u}, Giovanni and de Silva, Nadish and Kishida, Kohei and Mansfield, Shane}, title = {{Minimum Quantum Resources for Strong Non-Locality}}, booktitle = {12th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2017)}, pages = {9:1--9:20}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-034-7}, ISSN = {1868-8969}, year = {2018}, volume = {73}, editor = {Wilde, Mark M.}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.TQC.2017.9}, URN = {urn:nbn:de:0030-drops-85822}, doi = {10.4230/LIPIcs.TQC.2017.9}, annote = {Keywords: strong non-locality, maximal non-locality, quantum resources, three-qubit states} }
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