Abstract
Ising machines are annealing processors that can solve combinatorial optimization problems via the physical evolution of the corresponding Ising graphs. Such machines are, however, typically restricted to solving problems with certain kinds of graph topology because the spin location and connections are fixed. Here, we report a universal Ising machine that supports arbitrary Ising graph topology with reasonable hardware resources using a coarse-grained compressed sparse row method to compress and store sparse Ising graph adjacency matrices. The approach, which we term interaction-centric storage, is suitable for any kind of Ising graph and reduces the memory scaling cost. We experimentally implement the Ising machine using compute-in-memory hardware based on a 40 nm resistive random-access memory arrays. We use the machine to solve max-cut and graph colouring problems, with the latter showing a 442–1,450 factor improvement in speed and 4.1 × 105–6.0 × 105 factor reduction in energy consumption compared to a general-purpose graphics processing unit. We also use our Ising machine to solve a realistic electronic design automation problem—multiple patterning lithography layout decomposition—with 390–65,550 times speedup compared to the integer linear programming algorithm on a typical central processing unit.
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Data availability
Source data are available via Zenodo at https://doi.org/10.5281/zenodo.10686168 (ref. 41). Other data that support the findings of this study are available from the corresponding authors upon reasonable request.
Code availability
The core source code that implements the full-FPGA version of the UIM architecture is available via Zenodo at https://doi.org/10.5281/zenodo.10686168 (ref. 41). Other codes are available from the corresponding authors upon reasonable request.
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Acknowledgements
This work was supported by the National Key R&D Programme of China (grant no. 2023YFB4502200), National Natural Science Foundation of China (grant nos 61925401, 92064004, 61927901, 8206100486, 92164302 and 92364102), Beijing Natural Science Foundation (grant no. L234026) and the 111 Project (grant no. B18001). Fund grant nos 2023YFB4502200, 61925401, 92064004, 92164302 and L234026 were awarded to Yuchao Yang. Fund grant no. 61927901 was awarded to R.H. Fund grant no. 8206100486 was awarded to Y.T. Fund grant no. 92364102 was awarded to B.Y.
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B.Y. and Yuchao Yang directed the research. W.Y. and B.Y. conceived the idea and planned the study. W.Y., Z.J. and B.Y. designed the RRAM chip. W.Y. and B.Y. designed the UIM architecture. W.Y. implemented the closed-loop CIM-based UIM system. Y.L. extended the UIM to the EDA application. T.Z., Yuxiang Yang, Z.Y., Y.W., W.B., K.Z., J.K., R.H. and Yuchao Yang developed the RRAM integration processes. T.Z., W.Y., Yuxiang Yang, Z.Y., Y.W. and Y.T. optimized the RRAM device. W.Y. and K.W. developed the video demonstration. K.W. optimized the testing platform. All authors reviewed and edited the paper.
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Nature Electronics thanks Bin Gao, Luke Theogarajan and Masanao Yamaoka for their contribution to the peer review of this work.
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Supplementary Figs. 1–22, Notes 1–25 and Tables 1–12.
Supplementary Video 1
Computing process in the closed-loop system of the UIMe.
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Yue, W., Zhang, T., Jing, Z. et al. A scalable universal Ising machine based on interaction-centric storage and compute-in-memory. Nat Electron 7, 904–913 (2024). https://doi.org/10.1038/s41928-024-01228-7
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DOI: https://doi.org/10.1038/s41928-024-01228-7
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