  Thouless pumping enables the transport of particles in a one-dimensional
periodic potential if the potential is slowly and periodically modulated in
time. The change in the position of particles after each modulation period is
quantized and depends solely on the topology of the pump cycle, making it
robust against perturbations. Here, we demonstrate that Thouless pumping also
allows for the realization of topologically protected quantized changes of the
distance between atoms if the atomic s-wave scattering length is properly
modulated in time.
