Quantum entanglement is a physical phenomenon in which two particles remain connected over long distances so that the actions performed on one particle also have an effect on the second particle. If it sounds mind-boggling, it’s because it is. Albert Einstein, who first discussed the idea of quantum entanglement in a joint paper with Boris Podolsky and Nathan Rosen, dubbed the phenomenon “spooky action at a distance” because it implies faster than light communication, which his theory of relativity ruled out.
The particles in the entangled pair form an inseparable whole and one cannot be fully described without the other. However, entanglement is broken when particles interact with the environment, such as when a measurement is made. The paradox of quantum entanglement lies in the fact that a measurement of either one of the entangled particles collapses the entire system before the result of one measurement can be transmitted to the other particle. (more…)