Thinking Outside the Clock: Physical Design for Field-coupled Nanocomputing with Deep Reinforcement Learning.

Recent advances in atom-scale manufacturing are paving the way toward the emergence of Field-coupled Nanocomputing (FCN) as a viable real-world post-CMOS technology. Current FCN-specific solutions for placement and routing of logic functions are at risk of falling behind manufacturing capabilities. The problem lies in the fact that existing algorithms are either optimal in their result quality but do not scale; or are scalable, but produce results of sub-par quality limited to select clocking schemes. Furthermore, most existing approaches are tailored toward a concrete FCN implementation, limiting their applicability across the domain. To address these challenges, we propose a novel approach that utilizes deep reinforcement learning to learn the placement of logic elements and incorporate established routing strategies directly into the placement step. By relying only on abstract signal flow directions, this solution is technology-agnostic and therefore applicable to any FCN implementation, layout topology, or clocking scheme. The proposed approach is experimentally evaluated on a set of established benchmark functions common in the domain. While a state-of-the-art exact approach is limited to designing layouts for functions containing a maximum of around 40 gates, the proposed approach is able to generate solutions for all functions included in the considered benchmark sets, while reducing the layout area by an average of 59% compared to the state-of-the-art heuristic. Furthermore, the proposed algorithm is made available to the scientific community as an open-source implementation.