Experimental non-classicality of an indivisible quantum system

Autor(en)

Radek Lapkiewicz, Peizhe Li, Christoph Schäff, Nathan Langford, Sven Ramelow, Marcin Adam Wiesniak, Anton Zeilinger

Abstrakt

In contrast to classical physics, quantum theory demands that not all properties can be simultaneously well defined; the Heisenberg uncertainty principle is a manifestation of this fact(1). Alternatives have been explored-notably theories relying on joint probability distributions or non-contextual hidden-variable models, in which the properties of a system are defined independently of their own measurement and any other measurements that are made. Various deep theoretical results(2-5) imply that such theories are in conflict with quantum mechanics. Simpler cases demonstrating this conflict have been found(6-10) and tested experimentally(11,12) with pairs of quantum bits (qubits). Recently, an inequality satisfied by non-contextual hidden-variable models and violated by quantum mechanics for all states of two qubits was introduced(13) and tested experimentally(14-16). A single three-state system (a qutrit) is the simplest system in which such a contradiction is possible; moreover, the contradiction cannot result from entanglement between subsystems, because such a three-state system is indivisible. Here we report an experiment with single photonic qutrits(17,18) which provides evidence that no joint probability distribution describing the outcomes of all possible measurements-and, therefore, no non-contextual theory-can exist. Specifically, we observe a violation of the Bell-type inequality found by Klyachko, Can, Binicioglu and Shumovsky(19). Our results illustrate a deep incompatibility between quantum mechanics and classical physics that cannot in any way result from entanglement.

Organisation(en)

Quantenoptik, Quantennanophysik und Quanteninformation

Externe Organisation(en)

Universität Wien

Journal

Nature

Band

474

Seiten

490-493

Anzahl der Seiten

4

ISSN

0028-0836

DOI

https://doi.org/10.1038/nature10119

Publikationsdatum

2011

Peer-reviewed

Ja

ÖFOS 2012

103026 Quantenoptik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/31ee153c-93bd-4e1f-99c2-8fc1c1adada1