A CMOS-compatible oscillation-based VO2 Ising machine solver

• Published in: Nature communications 2024-04, Vol.15 (1), p.3334-11, Article 3334
• Main Authors: Maher, Olivier, Jiménez, Manuel, Delacour, Corentin, Harnack, Nele, Núñez, Juan, Avedillo, María J., Linares-Barranco, Bernabé, Todri-Sanial, Aida, Indiveri, Giacomo, Karg, Siegfried
• Format: Article
• Language: English
• Subjects: 142/126; 147/135; 639/166/987; 639/705/1042; 639/925/927/1007; Circuit design; Combinatorial analysis; Complexity; Engineering Sciences; Equivalence; Frequency locking; Graph coloring; Humanities and Social Sciences; Ising model; Micro and nanotechnologies; Microelectronics; multidisciplinary; Neural networks; Optimization; Oscillators; Polynomials; Power consumption; Power efficiency; Power management; Science; Science (multidisciplinary); Solution space; Vanadium; Vanadium dioxide; Vanadium oxides
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-47642-5

Phase-encoded oscillating neural networks offer compelling advantages over metal-oxide-semiconductor-based technology for tackling complex optimization problems, with promising potential for ultralow power consumption and exceptionally rapid computational performance. In this work, we investigate the ability of these networks to solve optimization problems belonging to the nondeterministic polynomial time complexity class using nanoscale vanadium-dioxide-based oscillators integrated onto a Silicon platform. Specifically, we demonstrate how the dynamic behavior of coupled vanadium dioxide devices can effectively solve combinatorial optimization problems, including Graph Coloring, Max-cut, and Max-3SAT problems. The electrical mappings of these problems are derived from the equivalent Ising Hamiltonian formulation to design circuits with up to nine crossbar vanadium dioxide oscillators. Using sub-harmonic injection locking techniques, we binarize the solution space provided by the oscillators and demonstrate that graphs with high connection density (η > 0.4) converge more easily towards the optimal solution due to the small spectral radius of the problem’s equivalent adjacency matrix. Our findings indicate that these systems achieve stability within 25 oscillation cycles and exhibit power efficiency and potential for scaling that surpasses available commercial options and other technologies under study. These results pave the way for accelerated parallel computing enabled by large-scale networks of interconnected oscillators. Oscillating neural networks promise ultralow power consumption and rapid computation for tackling complex optimization problems. Here, the authors demonstrate VO 2 oscillators to solve NP-complete problems with projected power consumption of 13 µW/oscillator.