Tuneable spin-glass optical simulator based on multiple light scattering

TL;DR

This paper demonstrates a tunable optical approach to simulate spin-glass systems, enabling programmable couplings and Hamiltonian modifications, advancing optical Ising machines for solving complex NP problems.

Contribution

It introduces a method to control spin couplings in optical Ising simulators using transmission matrix knowledge, allowing full programmability of the Hamiltonian.

Findings

Controlled couplings in a fully connected Ising system achieved

Modified Hamiltonian with external magnetic field demonstrated

Potential for large-scale, programmable optical Ising machines shown

Abstract

The race to heuristically solve non-deterministic polynomial-time (NP) problems through efficient methods is ongoing. Recently, optics was demonstrated as a promising tool to find the ground state of a spin-glass Ising Hamiltonian, which represents an archetypal NP problem. However, achieving completely programmable spin couplings in these large-scale optical Ising simulators remains an open challenge. Here, by exploiting the knowledge of the transmission matrix of a random medium, we experimentally demonstrate the possibility of controlling the couplings of a fully connected Ising spin system. By further tailoring the input wavefront we showcase the possibility of modifying the Ising Hamiltonian both by accounting for an external magnetic field and by controlling the number of degenerate ground states and their properties and probabilities. Our results represent a relevant step toward the realisation of fully-programmable Ising machines on thin optical platforms, capable of solving complex spin-glass Hamiltonians on a large scale.