Universality of entanglement in gluon dynamics

Abstract

Entanglement of fundamental degrees of freedom in particle physics is generated ab initio in scattering processes. In the case of a pure $SU(N)$ gauge theory, two gluons in a product state can be entangled in their polarizations as the result of three- and four-gluon vertex interactions. We find that entanglement is only produced when the initial product state have opposite polarizations, and that maximal entanglement is generated when the outgoing particles form an angle of $\fracπ{2}$ with respect to the incoming ones. A surprising result is that the amount of entanglement among gluon polarizations is independent of the gauge group at any angle and, thus, of the color degree of freedom. Universality of entanglement for any gauge group emerges. It is also found that a small deviation of the relative weight between three- and four-gluon vertices would prevent the generation of maximal entanglement. This can be seen as a small piece of a possible it from qubit principle underlying fundamental interactions, that is a principle that requires physics to be quantum in origin.