26 August 2010 Nature’s News and Views

Prof. Andreas Winter reviews recent research on nonlocal quantum games at the group led by Prof. Antonio Acin. In words of Prof. Winter, the results on quantum games presented by Dr. Almeida and her collaborators “reveal common ground between classical and quantum physics” by “providing a surprising twist of the foundations of quantum mechanics”.

The authors define a simple information-gain game: guess your neighbor\'s input. As one would expect, classical and quantum resources perform equally well at this game, since both resources are no-signaling and do not allow gain of information. Surprisingly, Almeida and her collaborators find that there exist other resources, stronger than quantum but still no-signaling, which provide an advantage. It is the first time that such behavior is observed for correlations involving more than two systems. These results suggest that physical correlations obey a generalized, multipartite, no-signaling principle. As David Voss, from APS concludes “the results spell out for the first time where quantum non-locality leaves off and where a stronger set of correlations can be found in multipartite situations”.

The results were published at PRL by Dr. Mafalda Almeida (former ICFO PhD student); PhD student Jean-Daniel Bancal, University of Geneve; researchers Dr. Nicolas Brunner, University of Bristol, Dr. Stefano Pironio, Free University of Brussels; and ICFO/ICREA Prof. Antonio Acín and Prof. Nicolas Gisin, University of Geneve.

This work had been previously highlighted in the APS web spotlight and in PhysicsOrg.