Partitioning and Placement for Buildable QCA Circuits

Abstract

Quantum-dot Cellular Automata (QCA) is a novel computing mechanism that can represent binary information based on spatial distribution of electron charge configuration in chemical molecules. It has the potential to allow for circuits and systems with functional densities that are better than end of the roadmap for CMOS, but also imposes new constraints on system designers. In this article, we present the first partitioning and placement algorithm for automatic QCA layout. The purpose of zone partitioning is to initially partition a given circuit such that a single clock potential modulates the inter-dot barriers in all of the QCA cells within each zone. We then place these zones as well as individual QCA cells in these zones during our placement step. We identify several objectives and constraints that will enhance the buildability of QCA circuits and use them in our optimization process. The results are intended to: (1) define what is computationally interesting and could actually be built within a set of predefined constraints, (2) project what designs will be possible as additional constructs become realizable, and (3) provide a vehicle that we can use to compare QCA systems to silicon-based systems.KeywordsNanotechnologyQuantum-dot Cellular Automatapartitioningplacement