Circuits and excitations to enable Brownian token-based computing with skyrmions

Abstract

Brownian computing exploits thermal motion of discrete signal carriers (tokens) for computations. In this paper, we address two major challenges that hinder competitive realizations of circuits and applications of Brownian token-based computing in actual devices, for instance, based on magnetic skyrmions. To overcome the problem that crossings generate for the fabrication of circuits, we design a crossing-free layout for a composite half-adder module. This layout greatly simplifies experimental implementations as wire crossings are effectively avoided. Additionally, our design is shorter to speed up computations compared to conventional designs. To address the key issue of slow computation based on thermal excitations, we propose to overlay artificial diffusion induced by an external excitation mechanism. For instance, if magnetic skyrmions are used as tokens, artificially induced diffusion by spin-orbit torques or other mechanisms increases the speed of computations by several orders of magnitude. Combined with conventional Brownian computing, the latter could greatly enhance the application scenarios of token-based computing, for example, for low power devices such as autonomous sensors with limited power that is harvested from the environment.