I. Introduction
Combinatorial optimization problems (COPs) exist in a wide spectrum of applications, including artificial intelligence, route planning, and scheduling [1]. For example, the optimizations in circuit layout design and routing algorithms are typical COPs in the semiconductor industry. Many COPs are nondeterministic polynomial-hard, so computationally intensive to solve. Recently, Ising model-based computers, or Ising machines, have emerged as efficient solutions for COPs.