Enter the two-dimensional electron gases (2DEGs) routinely created in compound semiconductor heterostructures. In two dimensions, it is theoretically possible to create states that are between fermion and boson; ‘anyons’, as they have been dubbed. Furthermore, it is theoretically possible for some anyons to be non-Abelian. While Abelian systems are blind to the order in which interactions take place, this is not the case with non-Abelian systems and, from this, topological properties can emerge and be manipulated.

One candidate for a non-Abelian anyon in a quantum Hall system has e/4. The first experiment suggesting a particle-like state (quasi-particle) of charge e/4 has just been published in Nature [Dolev et al, p.829, 17 April 2008]. Another experimental report is in preprint form, no doubt somewhere on the road to peer-reviewed publication [Radu et al, http://arxiv.org/abs/0803.3530, 2008]. The latter (involving researchers from MIT, Harvard University and Bell Labs) compares experimental tunneling conductance data with various models and finds that they are most consistent with a non-Abelian e/4 state. The Nature paper (Weizmann Institute of Science) uses shot-noise measurements to find that the charge state is consistent with charge e/4 but inconsistent with e or e/2.