Surprise link between weird quantum phenomena: Heisenberg uncertainty principle sets limits on Einstein's 'spooky action at a distance'

Researchers have uncovered a fundamental link between the two defining properties of quantum physics. The result is being heralded as a dramatic breakthrough in our basic understanding of quantum mechanics and provides new clues to researchers seeking to understand the foundations of quantum theory. The result addresses the question of why quantum behaviour is as weird as it is -- but no weirder.

Stephanie Wehner of Singapore's Centre for Quantum Technologies and the National University of Singapore and Jonathan Oppenheim of the United Kingdom's University of Cambridge published their work in the latest edition of the journal Science.

The strange behaviour of quantum particles, such as atoms, electrons and the photons that make up light, has perplexed scientists for nearly a century. Albert Einstein was among those who thought the quantum world was so strange that quantum theory must be wrong, but experiments have borne out the theory's predictions.

One of the weird aspects of quantum theory is that it is impossible to know certain things, such as a particle's momentum and position, simultaneously. Knowledge of one of these properties affects the accuracy with which you can learn the other. This is known as the "Heisenberg Uncertainty Principle."

Another weird aspect is the quantum phenomenon of non-locality, which arises from the better-known phenomenon of entanglement. When two quantum particles are entangled, they can perform actions that look as if they are coordinated with each other in ways that defy classical intuition about physically separated particles.

Previously, researchers have treated non-locality and uncertainty as two separate phenomena. Now Wehner and Oppenheim have shown that they are intricately linked. What's more, they show that this link is quantitative and have found an equation which shows that the "amount" of non-locality is determined by the uncertainty principle. ...

the uncertainty principle... imposes a strict bound on how strong non-locality can be.

The finding bears on the deep question of what principles underlie quantum physics.

via Surprise link between weird quantum phenomena: Heisenberg uncertainty principle sets limits on Einstein's 'spooky action at a distance'.