Experimental Demonstration of an Intensity-Resolved Coherent Ising Machine Based on Polarization Symmetry Breaking

Coherent Ising machines (CIMs) are optical devices that can offer efficient solutions to many complex combinatorial optimization problems too challenging to solve with traditional computing methods [1]–[3]. CIMs typically utilize networks of degenerate optical parametric oscillators, where the bistable phases of optical pulses represent spin states, and coupling is achieved through electronic measurement and feedback. While offering a powerful approach, exemplified by exceptional scaling [4], complex phase stabilization techniques make continuous operation of these machines quite challenging. Here, we provide an experimental demonstration of a novel CIM platform, with spin-states defined based on the polarization of optical pulses, and resolved with straightforward intensity measurements, leading to simple and robust operation [5]. The device is made up of a Kerr nonlinear optical fiber ring resonator synchronously-driven with multiple laser pulses. As the driving frequency is swept across a cavity resonance, each circulating pulse undergoes spontaneous polarization symmetry breaking, producing independent spin states. Crucially, we operate in a period-2 regime, where the polarization state of each intracavity pulse alternates at each roundtrip, imparting topological protection against external perturbations [6]. This guarantees highly robust performance, confirmed by high-fidelity all-optical random number generation [7].