Fig. 2. Inference on a probabilistic full adder.
a Fully-connected full adder network45, where p-bits are clocked by the sMTJs. b Truth table of the full adder where Dec. represents the decimal representation of the state of [A B Cin S Cout] from left to right. c Kullback-Leibler (KL) divergence between the ideal and measured distributions vs. the number of sweeps. Results are shown for LFSR-based p-bit (red line), sMTJ-clocked LFSR-based p-bit (blue line), and Xoshiro-based p-bit (green line). d Histogram for the measured and ideal distributions at the 106 sweep. The red, blue, and yellow bars show LFSR, sMTJ-clocked LFSR, and Boltzmann distribution, respectively. The histogram shows all 8 high probability states denoted in (b) and with a clear bias for the LFSR distribution (see Supplementary Note VII for full histograms for all PRNGs, including Xoshiro).