(Université de Genève) Transitions between phases of matter could result from topological excitations that force the particles to act in unison. Researchers from the UNIGE, CEA, CNRS and UGA have been studying BACOVO — a one-dimensional quantum material. They have discovered in this material a novel topological phase transition, governed not by a single type of topological excitation, but by two different ones. In addition, they were able to choose which of the two sets would dominate the other.