Entanglement, a quantum correlation in superposition states, is one of the most striking breaks of the quantum theory of matter and radiation from classical theory. In a light-front Fock state description of the proton, each Fock state corresponds to a superposition of quarks, anti-quarks, and gluons, of all possible combinations of colors, flavors, spins, and momenta. Entanglement of various degrees of freedom in the proton is currently being studied intensively.
After a brief introduction I will discuss the application of methods from Quantum Information Theory to scrutinize quantum correlations encoded in the double quark parton distribution function (dPDF) over light-cone momentum fractions x1 and x2. I also discuss performing one step of QCD scale evolution of the entire density matrix, not just its diagonal (dPDF), by computing collinearly divergent corrections due to the emission of a gluon, and finally present first qualitative numerical results for scale evolution of quantum entanglement correlations in double quark PDFs.