An Ising solver chip based on coupled ring oscillators with a 48-node all-to-all connected array architecture

Quantum-inspired computing systems can be used to efficiently solve combinatorial optimization problems. In developing such systems, a key challenge is the creation of large hardware topologies with all-to-all node connectivity that allow arbitrary problem graphs to be directly mapped to the hardware. Here we report a physics-based Ising solver chip fabricated in a standard 1.2 V, 65 nm complementary metal–oxide–semiconductor technology. The chip features an all-to-all architecture with 48 spins and a highly uniform coupling circuit with integer weights ranging from −14 to +14. The all-to-all architecture strongly couples a horizontal oscillator with a vertical oscillator so that each horizontal–vertical oscillator pair intersects with all the other pairs in a crossbar-style array and allows any graph with up to 48 nodes to be directly mapped to the hardware. We use the Ising solver chip to carry out statistical measurements for different problem sizes, graph densities, operating temperatures and problem instances.