Dear All,
The next QI Seminar is on Thursday November 29 at 5:00 pm, in IFW E44. Note that we will also shift our "research day" from Tuesday to Thursday next week.
Speaker: Valerio Scarani, Centre for Quantum Technologies, National University of Singapore
Title: "Reasonable" Models and Quantum Correlations
Abstract:
The measurement of entangled quantum particles produces outcomes that are correlated, even when the particles are separated by a large distance. There is no doubt on how these correlations should be computed with the formalism of quantum theory; countless experiments have been satisfactorily described by it, and in no case hints of a possible discrepancy have been observed. This looks very much like a textbook case.
Nevertheless, these "quantum correlations" are puzzling. Einstein and others already noticed that they cannot originate from communication, since the signal should travel faster than light. In 1964, John Bell found a way of testing the other classical origin, namely pre-established agreement; and subsequent experiments demonstrated that indeed pre-established agreement cannot be invoked either. So, neither of the usual classical causes can explain the observed correlations.
In the last years, more sophisticated models have been proposed. These models are "reasonable", in the sense that, while acknowledging that something special is at stake, still try and retain some "intuitive" features. This talk tells the story of these tests, which are helping us to understand quantum physics in greater depth.
Suggested readings:
For beginners in the field: V. Scarani, Quantum Physics - A First Encounter (Oxford University Press, Oxford, 2006)
For experts: C. Branciard, A.Ling, N. Gisin, C. Kurtsiefer, A. Lamas-Linares and V. Scarani, arXiv:0708.0584, to appear in Phys. Rev. Lett.; and references therein.
Cheers,
Dejan