Experimental Demonstration of an Intensity-Resolved Coherent Ising Machine Based on Polarization Symmetry Breaking
Liam Quinn, Yiqing Xu, Julien Fatome, Gian‐Luca Oppo, Stuart G. Murdoch, Miro J. Erkintalo, Stéphane Coen · 2025
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].