Entanglement entropy in CFT2

Abstract

The description of the general methodology for computing entanglement entropy in Chap. 2 gives a clean, albeit abstract prescription. As with any functional integral, it helps to develop some intuition as to where the computation can be carried out explicitly. For a general QFT in d > 2 the computation appears intractable in all but the simplest of cases of free field theories [42]. However, it turns out to be possible to leverage the power of conformal symmetry in d = 2, to explicitly compute entanglement entropy in some situations [18]. In fact, the revival of interest in entanglement entropy can be traced to the work of Cardy and Calabrese [57] who re-derived the results of [58] and went on to then explore its utility as a diagnostic of interesting physical phenomena in interacting systems. We will give a brief overview of this discussion, adapting it both to the general ideas outlined above and simultaneously preparing the group for our holographic considerations in the sequel.