A 16-bit Coherent Ising Machine for One-Dimensional Ring and Cubic Graph Problems

TL;DR

This paper presents a 16-bit coherent Ising machine using optical oscillators that successfully solves certain 1D ring and NP-hard problems with high success rates, demonstrating improved performance through gradual pumping and multimode operation.

Contribution

It introduces a 16-bit coherent Ising machine based on femtosecond optical parametric oscillators, advancing physical hardware solutions for complex combinatorial optimization problems.

Findings

Achieved over 99.6% success rate on 1D Ising ring problems.

Demonstrated effectiveness on NP-hard instances.

Improved performance with gradual pumping and multimode pulses.

Abstract

Many tasks in our modern life, such as planning an efficient travel, image processing and optimizing integrated circuit design, are modeled as complex combinatorial optimization problems with binary variables. Such problems can be mapped to finding a ground state of the Ising Hamiltonian, thus various physical systems have been studied to emulate and solve this Ising problem. Recently, networks of mutually injected optical oscillators, called coherent Ising machines, have been developed as promising solvers for the problem, benefiting from programmability, scalability and room temperature operation. Here, we report a 16-bit coherent Ising machine based on a network of time-division-multiplexed femtosecond degenerate optical parametric oscillators. The system experimentally gives more than 99.6 % of success rates for one-dimensional Ising ring and nondeterministic polynomial-time (NP) hard instances. The experimental and numerical results indicate that gradual pumping of the network combined with multiple spectral and temporal modes of the femtosecond pulses can improve the computational performance of the Ising machine, offering a new path for tackling larger and more complex instances.