PyCIM: A Python Framework for the Dynamics of Coherent Ising Machine

Coherent Ising Machine (CIM) as an optical device for solving combinatorial optimization problems has received significant attention. However, the core unit of CIM, degenerate optical parametric oscillator (DOPO), is an open dissipative system and exhibits complicated dynamics, making the analysis and design of CIM challenging. Based on existing theoretical models for describing CIM, we develop PyCIM. To the best of our knowledge, PyCIM is the first simulator that can produce the dynamic behavior of CIM. We effectively capture some characteristic phenomena of DOPO and CIM, including a spontaneous symmetry breaking, threshold behavior, gain saturation, and the process of CIM solving MAX-CUT problems. Additionally, we implement time-varying coupling strengths and pump schedules. Moreover, we analyze the impact of parameters on the performance of CIM, which can be used to guide the design and optimization of actual physical systems. Finally, we evaluate the performance of the CIM on a standard graph benchmark set.