Figure 2.

Autonomous behavioral model for p-bit: (A–D) Behavioral model for the autonomous hardware with design 1 (Figure 1B) is benchmarked with SPICE simulations of the actual device involving experimentally benchmarked modules. The behavioral model (labeled as “PPSL”) shows good agreement with SPICE in terms of capturing fluctuation dynamics (A), steady-state sigmoidal response (B), and two different time responses: autocorrelation time of the fluctuating output under zero input condition labeled as τ_corr (C), which is proportional to the LBM retention time τ_N in the nanosecond range, and the step response time τ_step (D) that is proportional to transistor response time τ_T, which is few picoseconds and much smaller than τ_N. The magnet parameters used in the simulations are mentioned in section 2. (E–H) Similar benchmarking for p-bit design 2 (Figure 1C). In this case, τ_step is proportional to τ_N. For (B,F), each point for the SPICE simulation was obtained by averaging m_i over 1 μs. The step response time for (D,H) is obtained by averaging over 2,000 ensembles where I_i = −5 at t < 0 and I_i = 0 at t > 0.