976 publications from this institution
In relativity there is space-time out there. In quantum mechanics there is entanglement. Entanglement manifests itself by producing correlations between classical events (e.g. the firing of some detectors) at any two space-time locations. If the locations are time-like separated, i.e. one is in the future of the other, then there is no specific difficulty to understand the correlations. But if the two locations are space-like separated, the problem is different. How can the two space-time locations out there know about what happens in each other without any sort of communication? If space-time really exists, the locations must do something like communicating. Or it was all set up at the Beginning. But the correlations depend also on the free choice of the experimentalists, one in each space-time location. This allowed John Bell to derive his inequality and the experimentalists to violate it, thus refuting the assumption that it was all set up at the beginning: the Correlations can't be explained by common causes.
We investigate the assumption that quantum entangled states Ψ do spontaneously collapse into a mixture of the product states occurring in the Schmidt decomposition of Ψ. We prove that this assumption introduces new observables in quantum mechanics. In particular mixtures that are indistinguishable according to standard quantum mechanics, would be distinguishable. Since such mixtures can be prepared at an arbitrarily large distance, the assumption activates the quantum non-locality.
