Better Bell-inequality violation by collective measurements

Yeong Cherng Liang, Andrew C. Doherty

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


The standard Bell-inequality experiments test for violation of local realism by repeatedly making local measurements on individual copies of an entangled quantum state. Here we investigate the possibility of increasing the violation of a Bell inequality by making collective measurements. We show that the nonlocality of bipartite pure entangled states, quantified by their maximal violation of the Bell-Clauser-Horne inequality, can always be enhanced by collective measurements, even without communication between the parties. For mixed states we also show that collective measurements can increase the violation of Bell inequalities, although numerical evidence suggests that the phenomenon is not common as it is for pure states.

Original languageEnglish
Article number052116
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
Publication statusPublished - 2006

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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