Bell's 1964 theorem, which states that the predictions of quantum theory cannot be
accounted for by any local theory, represents one of the most profound developments in the …

How can one prove that a given quantum state is entangled? In this paper we review
different methods that have been proposed for entanglement detection. We first explain the …

The question of whether quantum phenomena can be explained by classical models with
hidden variables is the subject of a long-lasting debate,. In 1964, Bell showed that certain …

Nonlocality was discovered by John Bell in 1964, in the context of the debates about
quantum theory, but is a phenomenon that can be studied in its own right. Its observation …

The derivation of Bell inequalities requires an assumption of measurement independence,
related to the amount of free will experimenters have in choosing measurement settings …

We present an experimental state-independent violation of an inequality for noncontextual
theories on single particles. We show that 20 different single-photon states violate an …

According to quantum theory, measurements generate random outcomes, in stark contrast
with classical mechanics. This raises the question of whether there could exist an extension …

The combination of various physically plausible properties, such as no signaling,
determinism, and experimental free will, is known to be incompatible with quantum …

We show that, assuming that quantum mechanics holds locally, the finite speed of
information is the principle that limits all possible correlations between distant parties to be …

A basic assumption behind the inequalities used for testing noncontextual hidden variable
models is that the observables measured on the same individual system are perfectly …