All-to-all reconfigurability with sparse and higher-order Ising machines

• Published in: Nature communications Vol. 15; no. 1; pp. 8977 - 11
• Main Authors: Nikhar, Srijan, Kannan, Sidharth, Aadit, Navid Anjum, Chowdhury, Shuvro, Camsari, Kerem Y.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17-10-2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/166/987; 639/705/117; 639/766; Adaptive algorithms; Adaptive sampling; Algorithms; Computer architecture; Field programmable gate arrays; Graphics processing units; Greedy algorithms; Hardware; Humanities and Social Sciences; Ising model; multidisciplinary; Multiplexing; Optimization; Science; Science (multidisciplinary); Tempering
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-53270-w

Domain-specific hardware to solve computationally hard optimization problems has generated tremendous excitement. Here, we evaluate probabilistic bit (p-bit) based Ising Machines (IM) on the 3-Regular 3-Exclusive OR Satisfiability (3R3X), as a representative hard optimization problem. We first introduce a multiplexed architecture that emulates all-to-all network functionality while maintaining highly parallelized chromatic Gibbs sampling. We implement this architecture in a single Field-Programmable Gate Array (FPGA) and show that running the adaptive parallel tempering algorithm demonstrates competitive algorithmic and prefactor advantages over alternative IMs by D-Wave, Toshiba, and Fujitsu. We also implement higher-order interactions that lead to better prefactors without changing algorithmic scaling for the XORSAT problem. Even though FPGA implementations of p-bits are still not quite as fast as the best possible greedy algorithms accelerated on Graphics Processing Units (GPU), scaled magnetic versions of p-bit IMs could lead to orders of magnitude improvements over the state of the art for generic optimization.
Specialized hardware for hard optimization is gaining traction. Here, the authors introduce a sparse, multiplexed, and reconfigurable p-bit Ising Machine on Field-Programmable Gate Arrays, using adaptive parallel tempering and higher-order interactions to achieve competitive performance on the 3-Regular 3-XORSAT problem.