Lee Woojin, Kim Hyunjin, Jung Hyundo, Choi Yohan, Jeon Jinwoo, Kim Chulwoo
Department of Electrical Engineering, Korea University, Seoul, Korea.
Sci Rep. 2025 Mar 7;15(1):8018. doi: 10.1038/s41598-025-93218-8.
Probabilistic computing-quantum-inspired computing that uses probabilistic bits (p-bits)-has emerged as a powerful method owing to its fast search speed and robust connectivity. Previous works used linear feedback shift registers (LFSRs) or stochastic magnetic tunnel junctions (MTJs) to implement p-bits. However, in large-scale problems, periodicity and correlation issues in LFSR p-bits and inherent variations in MTJ-based p-bits with narrow stochastic regions lead to unreliable results when seeking the appropriate solution. Therefore, we propose a fully CMOS frequency-scalable p-bit implemented with a discrete-time flipped-hook tent-map chaotic oscillator. The proposed chaotic oscillator produces high-quality noise voltage that is uniformly distributed across the entire supply voltage range, enabling aligned responses of p-bits free from calibration and an input resolution of 8 bits. In contrast to LFSR-based p-bits with hardware-dependent correlation, the chaotic oscillator p-bits could factorize semiprimes with lengths up to 64 bits without changing hardware size. The chaotic oscillator exhibited an energy efficiency of 4.26 pJ/bit at 1.8 V supply voltage. The robustness and the high randomness of the proposed chaotic oscillator p-bit suggest a new direction of a p-bit scalable to large-scale probabilistic computing.
概率计算——一种利用概率比特（p比特）的量子启发式计算——因其快速的搜索速度和强大的连通性而成为一种强大的方法。先前的工作使用线性反馈移位寄存器（LFSR）或随机磁隧道结（MTJ）来实现p比特。然而，在大规模问题中，LFSR p比特的周期性和相关性问题以及基于MTJ的p比特在狭窄随机区域内的固有变化，导致在寻找合适解决方案时结果不可靠。因此，我们提出了一种采用离散时间翻转钩形帐篷图混沌振荡器实现的全CMOS频率可扩展p比特。所提出的混沌振荡器产生高质量的噪声电压，该电压在整个电源电压范围内均匀分布，使得p比特无需校准即可实现对齐响应，并且输入分辨率为8比特。与具有硬件相关相关性的基于LFSR的p比特不同，混沌振荡器p比特可以在不改变硬件尺寸的情况下对长度达64比特的半素数进行因式分解。在1.8 V电源电压下，混沌振荡器的能量效率为4.26 pJ/比特。所提出的混沌振荡器p比特的鲁棒性和高随机性为可扩展到大规模概率计算的p比特指明了一个新方向。
