Alberto Fernandez-Nieves1 Perry Ellis1 Daniel Pearce2 Luca Giomi2 Ya-Wen Chang1

1, Georgia Institute of Technology, Atlanta, Georgia, United States
2, Leiden University, Leiden, , Netherlands

We will discuss our recent results with active nematics on toroidal surfaces and show how, despite the intrinsic activity and out-of-equilibrium character of our system, we still observe remnants of the expected curvature-induced defect unbinding prediceted for regular nematics. In our experiments, however, the number of defects is far larger than what one would expect for regular nematics. In addition, these defects move throughout the toroidal surface and explore "phase space", bringing about interesting analogies with what we could call the high-temperature limit of regular nematic liquid crystals. By comparing the experiments with numerical simulations, we unravel the role of activity and perform defect microrheology, which enables us to extract the material properties of the active nematic liquid crystal.