Exhaustive search for low autocorrelation binary sequences

Abstract

Binary sequences with low autocorrelations are important in communication engineering and in statistical mechanics as groundstates of the Bernasconi-model. Computer searches are the main tool to construct such sequences. Due to the exponential size $O(2^N)$ of the configuration space, exhaustive searches are limited to short sequences. We discuss an exhaustive search algorithm with run time characteristic $O(1.85^N)$ and apply it to compile a table of exact groundstates of the Bernasconi-model up to $N=48$. The data suggests $F>9$ for the optimal merit factor in the limit $N\to\infty$.