Computing with random quantum dot repulsion

Quantum dot cellular automata (QCA) show great promise for fast computation with larger integration density and lower power consumption. Unfortunately, previous research has shown that QCA are likely to be extremely sensitive to placement error. During an investigation into placement sensitivity, it was discovered that completely random quantum dot structures have the ability to compute simple binary functions. In this paper, we further explore the random structures in an idealized way, looking for higher-order functions; an example of one-bit full adder is shown in the paper. Moreover, a new structure, the semi-random structure, is introduced to alleviate some, but not all, difficulties in connecting disparate random structures; the difficulties arise from the fact that inputs and outputs to and from a purely random structure may not reside at the edges of the structure. In the semi-random structure, the inputs and outputs are localized to the edges. It is demonstrated that semi-random structures, like random structures, can almost assuredly compute simple Boolean functions.