An experimental test of noncontextuality without unwarranted idealizations

Understand

To make precise the sense in which nature fails to respect classical physics, one requires a formal notion of classicality.

• Ideally, such a notion should be defined operationally, so that it can be subjected to a direct experimental test, and it should be applicable in a wide variety of experimental scenarios, so that it can cover the breadth of phenomena that are thought to defy classical understanding.
• Bell's notion of local causality fulfills the first criterion but not the second.
• The notion of noncontextuality fulfills the second criterion, but it is a long-standing question whether it can be made to fulfill the first.