Observation, Contextuality, and Realism

Andrei Yu. Khrennikov

We discuss the problem of interpretation of the wave function. The latest version of the Växjö interpretation is presented. It differs essentially from the original Växjö interpretation (2001). The main distinguishing feature of the present Växjö interpretation is the combination of realism on the subquantum level with nonobjectivity of quantum observables (i.e., impossibility to assign their values before measurements). Hence, realism is destroyed by detectors transforming continuous subquantum reality into discrete events, clicks of detectors. The Växjö interpretation-2012 is fundamentally contextual in the sense that the value of an observable depends on measurement context. This is contextuality in Bohr's sense. It is more general than Bell's contextuality based on joint measurements of compatible observables.

George Jaroszkiewicz

Yuki Sagawa, Jonte R. Hance, Holger Friedrich Hofmann +1 more

Quantum contextuality, where measurement outcomes depend on the measurement context, implies a failure of classical realism in quantum systems. As recently shown, the transition between measurement contexts can be mapped onto the path that a quantum particle takes through an interferometer. Here, we investigate the relation between contextuality and the counterfactual gain observed in the output ports of such an interferometer when one of the paths is blocked. It is shown that experimental evidence of contextuality can only be obtained when counterfactual gain is observed for a specific combination of blocked path and output port. Using a silicon photonic integrated circuit, we experimentally observe the counterfactual gain for a selection of input states and evaluate the associated evidence for contextuality. The results confirm that contextuality can only be observed in the presence of counterfactual gain.

Ghenadie N. Mardari

Predetermined physical properties cannot manifest at the same time if they are mutually exclusive. As part of a single system, they become observable at different times, in sequence. In this case, pairwise detections in a narrow window of coincidence allow for maximal Bell violations (S=4 for the CHSH protocol), without room for doubt about the local nature of the process. This shows that a deeper description of physical reality is possible, as suggested by Einstein, Podolsky and Rosen. Though, a more inclusive definition of Realism is required, in order to account for Bohr’s Contextuality.