  Topologically ordered phase has emerged as one of most exciting concepts that
not only broadens our understanding of phases of matter, but also has been
found to have potential application in fault-tolerant quantum computation. The
direct measurement of topological properties, however, is still a challenge
especially in interacting quantum system. Here we realize one-dimensional
Heisenberg spin chains using nuclear magnetic resonance simulators and observe
the interaction-induced topological transitions, where Berry curvature in the
parameter space of Hamiltonian is probed by means of dynamical response and
then the first Chern number is extracted by integrating the curvature over the
closed surface. The utilized experimental method provides a powerful means to
explore topological phenomena in quantum systems with many-body interactions.
