Quantized dynamical pumping via dissipation in a mechanical Thouless pump

Thouless pumps are time-periodic one-dimensional systems that capture the physics of the two-dimensional quantum Hall effect via the quantized pumping of particles under adiabatic modulation. Recent work in photonics has shown that nonlinearity can act to quantize the displacement of light in the form of soliton motion. Here we use a mechanical system, namely, coupled pendulums described by the Frenkel-Kontorova model, to propose and observe quantized nonadiabatic Thouless pumping using topological kink solitons. The pumping proceeds by a qualitatively different mechanism compared to Thouless' original proposal as the pump is nonadiabatic and dissipation is necessary. In the presence of an additional potential gradient along the pump, we predict and observe the emergence of quantized transport against the pumping direction as a function of the period and show the emergence of a rich plateau structure; this quantization is unique to dissipative systems and cannot be described by the Chern number. Finally, we experimentally demonstrate the robustness of the process by pumping the soliton through a tunable nonlinear defect.