2011/06/22 by Radek Lapkiewicz, Peizhe Li, Christoph Schaeff +4 · 3 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1038/nature10119
published as Nature 474, 490 (2011) · 11 pages, 4 figures, 2 tables
arxiv created 2011/06/22 · arxiv updated 2011/06/23
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.