In this lecture, we discussed some simple results from quantum information.We showed how entanglement could be quantified using a simple set of two-point correlators called CHSH correlators. These correlators also allow for a beautiful formulation of the "monogamy of entanglement."
We then went on to discuss the average entanglement between subsystems of a large system. We showed that, in a typical state, for a pair of pseudospin operators in the smaller system, it is possible to find a set of operators in the larger system so that the two pairs are maximally entangled.
We also derived the Page curve for the entanglement entropy between the two subsystems.