Editing Tsirelson's bound (section)

{{short description|Theoretical upper limit to non-local correlations in quantum mechanics}}
A '''Tsirelson bound''' is an upper limit to quantum mechanical correlations between distant events. Given that quantum mechanics violates [[Bell inequalities]] (i.e., it cannot be described by a [[local hidden-variable theory]]), a natural question to ask is how large can the violation be. The answer is precisely the Tsirelson bound for the particular Bell inequality in question. In general, this bound is lower than the bound that would be obtained if more general theories, only constrained by "no-signalling" (i.e., that they do not permit communication faster than light), were considered, and much research has been dedicated to the question of why this is the case.

The Tsirelson bounds are named after [[Boris Tsirelson|Boris S. Tsirelson]] (or Cirel'son, in a different [[Romanization of Russian|transliteration]]), the author of the article<ref>{{cite journal | last=Cirel'son | first=B. S. | title=Quantum generalizations of Bell's inequality | journal=Letters in Mathematical Physics | volume=4 | issue=2 | year=1980 | issn=0377-9017 | doi=10.1007/bf00417500 | pages=93–100|url=http://www.tau.ac.il/~tsirel/download/qbell80.html| bibcode=1980LMaPh...4...93C | s2cid=120680226 | url-access=subscription }}</ref> in which the first one was derived.