Holographic dual of free field theory

The simplest possible example of AdS/CFT duaiity was proposed around 1999 by Sundborg, between free quantum field theory and a theory of gravity and higher spin fields developed by Vasiliev and others. Evidence has accumulated for it, most recently in work of Giombi and Yin, but as yet there is no proof. In the recent work arXiv:1011.4926 with Luca Mazzucato and Shlomo Razamat, we prove the duality between free quantum fields and a modified version of higher spin gravity, by re-interpreting the exact renormalization group.