Sigurður Örn Stefánsson received his PhD in mathematical physics from the University of Iceland in 2010. Since September 2010 he is a Fellow at Nordita.

His previous research was on random graphs and random walk on graphs. The main focus was on studying weak limits of sequences of probability measures on trees and obtaining properties of the limiting measures. The tree models were motivated by equilibrium statistical mechanical models used in two dimensional quantum gravity and by nonequilibrium models originating from biological applications.

Currently he is interested in continuum scaling limits of graphs, especially regarding universality i.e. how different discrete structures yield the same scaling limit. He is studying the scaling limit of certain tree models and surface models with the goal of identifying new universality classes. These problems are interesting from a pure mathematics point of view and have in many cases direct relation to physics models. Recently, Sigurður also started a theoretical study of transport of particles through microchannels in collaboration with Ralf Eichhorn at Nordita.