Macrorealism Emerging from Quantum Physics

Tommaso Calarco, Roberto Onofrio

Fabio Benatti, G. C. Ghirardi, Renata Grassi

Roope Uola, Giuseppe Vitagliano, Costantino Budroni

Macrorealism, the notion that macroscopic physical properties are well defined at all times and that it is possible to measure the properties without disturbing them, is tricky to test in an experiment, by admitting the ``clumsiness loophole.'' Here, a compatibility condition is found, so that a generalized version of macrorealism can hold for every initial state. This allows one to design stricter experimental tests of macrorealism for which an explanation in terms of ``clumsy'' measurements is harder to justify.

G. C. Ghirardi

Sumit Mukherjee, Anik Rudra, Debarshi Das +2 more

We investigate quantum violation of macrorealism for multilevel spin systems under the condition of coarsening of measurement times, i.e., when measurement times have experimental indeterminacy. This is studied together with the effect of coarsening of measurement outcomes for which individual outcomes cannot be unambiguously discriminated. In our treatment, along with different measurement outcomes being combined into two groups in order to model the coarsening of measurement outcomes, importantly, varying degrees of coarsening of measurement time intervals have also been considered. This then reveals that while, for a given dimension, the magnitude of quantum violation of macrorealism decreases with the increasing degree of coarsening of measurement times, interestingly, this effect of coarsening of measurement times can be annulled by increasing the dimension of the spin system so that in the limit of large spin, the quantum violation of macrorealism continues to persist. Thus, the result obtained demonstrates that classicality for large spins does not emerge from quantum mechanics in spite of the coarsening of measurement times.

A. J. Leggett