Understanding the influence of hardware resolution on the performance of photonic Ising machines

An Ising machine (IM) is a novel natural computing system that could solve complex optimization problems more efficiently than traditional digital computers. In IMs, a problem is encoded into a network of non-linear elements, where the optimal solution is found by minimizing the network’s energy through an iterative feedback loop. Most of modern-day photonic-IM implementations have a hybrid layout where the problem variables are implemented in the analog domain, but the feedback signal is first calculated on traditional digital hardware before converted back into an analog signal. This latter conversion is implemented by an optical modulator, which have a significantly lower resolution than electronic modulators. Using numerical simulations, we investigate the influence of the limited modulator resolution on the performance of photonic-IMs and demonstrate that a 1-bit-resolution can improve the time-to-solution by at least an order of magnitude.