Einstein said that the wave function does not describe the physical state of a single object, but the possible states of an ensemble. He also said that quantum mechanics is not complete; there must be ...

Quantum theory predicts the existence of so-called tripartite-entangled states, in which three quantum particles are related in a way that has no counterpart in classical physics. Theoretical ...

Bell's theorem, the well-known theoretical framework introduced by John Bell decades ago, delineates the limits of classical physical processes arising from relativistic causality principles. These ...

The result highlights a fundamental tension: Either the rules of quantum mechanics don’t always apply, or at least one basic assumption about reality must be wrong. The founders of quantum mechanics ...

We take for granted that an event in one part of the world cannot instantly affect what happens far away. This principle, which physicists call locality, was long regarded as a bedrock assumption ...