Experimental non-classicality of an indivisible quantum system

Author(s): R. Lapkiewicz, P. Li, N. K. Langford, S. Ramelow, M. Wieśniak, A. Zeilinger

Journal: Nature

Volume: 474

Page(s): 490–493

Year: 2011

DOI Number: 10.1038/nature10119

Link: Link to publication


Quantum theory demands that, in contrast to classical physics, not all properties can be simultaneously well defined. The Heisenberg Uncertainty Principle is a manifestation of this fact. Another important corollary arises that there can be no joint probability distribution describing the outcomes of all possible measurements, allowing a quantum system to be classically understood. We provide the first experimental evidence that even for a single three-state system, a qutrit, no such classical model can exist that correctly describes the results of a simple set of pairwise compatible measurements. Not only is a single qutrit the simplest system in which such a contradiction is possible, but, even more importantly, the contradiction cannot result from entanglement, because such a system is indivisible, and it does not even allow the concept of entanglement between subsystems.

Note: http://arxiv.org/abs/1106.4481

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