Condition for macroscopic realism beyond the Leggett-Garg inequalities

Author(s): J. Kofler, Č. Brukner

Journal: Phys. Rev. A

Volume: 87

Page(s): 052115

Year: 2013

DOI Number: 10.1103/PhysRevA.87.052115

Link: Link to publication


In 1985, Leggett and Garg put forward the concept of macroscopic realism (macrorealism) and, in analogy to Bell's theorem, derived a necessary condition in terms of inequalities, which are now known as the Leggett-Garg inequalities. In this paper, we discuss another necessary condition called no-signaling in time. It solely bases on comparing the probability distribution for a macrovariable at some time for the cases where previously a measurement has or has not been performed. Although the concept is analogous to the no-signaling condition in the case of Bell tests, it can be violated according to quantum mechanical predictions even in situations where no violation of Leggett-Garg inequalities is possible.


Brukner Group Brukner Group