Limitations in Parallel Ising Machine Networks: Theory and Practice

Abstract: Analog Ising machines (IMs) occupy an increasingly prominent area of computer architecture research, offering high-quality and low latency/energy solutions to intractable computing tasks. However, IMs have a fixed capacity, with little to no utility in out-of-capacity problems. Previous works have proposed parallel, multi-IM architectures to circumvent this limitation. In this work we theoretically and numerically investigate tradeoffs in parallel IM networks to guide researchers in this burgeoning field. We propose formal models of parallel IM excution models, then provide theoretical guarantees for probabilistic convergence. Numerical experiments illustrate our findings and provide empirical insight into high and low synchronization frequency regimes. We also provide practical heuristics for parameter/model selection, informed by our theoretical and numerical findings.