Quantum Versus Physical Coupling of Entangled Quantum Resonators

There have been lots of debates about the concept of entanglement since Einstein’s famous statement “spooky action at a distance.” This contribution first reviews the main stages of the acceptance history of the concept of quantum entanglement. It then presents a comparison between the quantum and the physical coupling of two entangled quantum resonators, where the term physical is used in its classically intuitive sense. It is shown that both conform to Einstein’s theory of relativity and does not allow for either instantaneous or superluminal transmission of information. The physical model relies on connecting the two quantum resonators via a waveguide operating below the cutoff frequency of its dominant mode. Apparent superluminality might take place within the isolated lossless system. Coupling the system to its surroundings for conducting a measurement or observation breaks such apparent superluminality and makes the system conform to relativity constraints. A comprehensive transient analysis of the physical model might be needed to understand its role in the entanglement and how it interacts with the quantum one. It is, however, worth mentioning that although the analysis presented in this article is valid for resonant circuits, it cannot be applied to entangled moving particles, like electrons and photons, because of the lack of physical coupling in these cases.