Racetrack computing with a topological boundary ratchet

Abstract: Multistable order parameters provide a natural means of encoding non-volatile information in spatial domains, a concept that forms the foundation of magnetic memory devices. However, this stability inherently conflicts with the need to move information around the device for processing and readout. While in magnetic systems, domains can be transported using currents or external fields, mechanisms to robustly shuttle information-bearing domains across neutral systems are scarce. Here, we experimentally realize a topological boundary ratchet in an elastic metamaterial, where digital information is encoded in buckling domains and transported in a quantized manner via cyclic loading. The transport is topological in origin: neighboring domains act as different topological pumps for their Bogoliubov excitations, so their interface hosts topological boundary modes. Cyclic loading renders these modes unstable through inter-domain pressure, which in turn drives the motion of the domain wall. We demonstrate that the direction of information propagation can be controlled through adjustable mechanical constraints on the buckling beams, and numerically investigate buckling-based domain-wall logic circuits in an elastic metamaterial network. The underlying tight-binding structure with low-order nonlinearities makes this approach a general pathway toward racetrack memories in neutral systems.