# Snowball: A Scalable All-to-All Ising Machine with Dual-Mode Markov Chain Monte Carlo Spin Selection and Asynchronous Spin Updates for Fast Combinatorial Optimization

arXiv: https://arxiv.org/abs/2601.21058 · HTML: https://mlsanity.com/paper/2601.21058/

## Key facts

- No citing papers in the map yet (data through 14 Oct 2026).
- Builds on 1 of its 59 references that are in the map.
- First posted on arXiv 28 Jan 2026.

## Builds on (most cited first, 1 of 1)

- [Ising formulations of many NP problems](https://mlsanity.com/paper/1302.5843/) (2013)

## Abstract (arXiv)

Ising machines have emerged as accelerators for combinatorial optimization. To enable practical deployment, this work aims to reduce time-to-solution by addressing three challenges: (1) hardware topology, (2) spin selection and update algorithms, and (3) scalable coupling-coefficient precision. Restricted topologies require minor embedding; naive parallel updates can oscillate or stall; and limited precision can preclude feasible mappings or degrade solution quality. This work presents Snowball, a digital, scalable, all-to-all coupled Ising machine that integrates dual-mode Markov chain Monte Carlo spin selection with asynchronous spin updates to promote convergence and reduce time-to-solution. The digital architecture supports wide, configurable coupling precision, unlike many analog realizations at high bit widths. A prototype on an AMD Alveo U250 accelerator card achieves an 8× reduction in time-to-solution relative to a state-of-the-art Ising machine on the same benchmark instance.