# Coherent Ising machine based on polarization symmetry breaking in a driven Kerr resonator

## TL;DR

A new optical Ising machine uses polarization instead of phase to encode spins, eliminating the need for complex phase stabilization.

## Contribution

A novel optical Ising machine architecture that encodes spins in polarization state, enabling robust intensity-based readout and eliminating phase stabilization.

## Key findings

- Spins are encoded in polarization state, allowing intensity-based readout with telecom components.
- The system operates in a regime where nonlinearity and topology lock symmetry, enabling stable operation for over an hour.
- This approach simplifies hardware and enables high-throughput optical optimization.

## Abstract

Time-multiplexed networks of degenerate optical parametric oscillators have demonstrated remarkable success in simulating coupled Ising spins, thus providing a promising route to solving complex combinatorial optimization problems. In these systems, referred to as coherent Ising machines, spins are encoded in the oscillator phases, and measured at the system output using phase-sensitive techniques, making intricate phase stabilization necessary. Here, we introduce an optical Ising machine based on spontaneous polarization symmetry breaking in a coherently driven fiber Kerr nonlinear resonator. In our architecture, the spins are encoded in the polarization state, allowing robust, all-intensity readout with off-the-shelf telecom components. By operating in a newly-discovered regime where nonlinearity and topology lock the system’s symmetry, we eliminate drift and bias, enabling uninterrupted Ising trials at optical speeds for over an hour, without manual intervention. This all-fiber platform not only simplifies the hardware but also opens a path to more stable, high-throughput coherent optical optimization devices for applications from finance to drug design and beyond.

Coherent Ising machines suffer from stringent phase stabilization requirements. Here, authors provide a proof-of-concept demonstration of an optical coherent Ising machine, where spins are encoded in the polarization of light and can be accessed via intensity measurements, thereby lifting the limitations related to phase stabilization.