Realizing spin-Hamiltonians in nanoscale active photonic lattices

TL;DR

This paper demonstrates how nanoscale active photonic lattices can emulate spin Hamiltonians, allowing the study of magnetic interactions and optimization problems through experimental and theoretical analysis of coupled nanolasers.

Contribution

It introduces a novel nanophotonic platform that emulates spin models, including XY Hamiltonians, with experimental validation and analysis of geometrical frustration effects.

Findings

Nanolaser lattices can simulate XY spin Hamiltonians.

Active photonic structures exhibit phases similar to ferromagnetic and antiferromagnetic states.

Geometrical frustration can be achieved depending on lattice shape and modes.

Abstract

Spin models arise in the microscopic description of magnetic materials, where the macroscopic characteristics are governed by exchange interactions among the constituent magnetic moments. Recently, there has been a growing interest in complex systems with spin Hamiltonians, largely due to the rich behaviors exhibited by such interactions at the macroscale. Along these lines, it has been shown that certain classes of optimization problems involving large degrees of freedom can be effectively mapped into classical spin models. In this vein, the respective extremum can be found by identifying the ground state of the associated spin Hamiltonian. Here, we show both theoretically and experimentally, that the cooperative interplay among vectorial electromagnetic modes in coupled metallic nanolasers can be utilized as a means to emulate certain types of spin-like systems. The ensuing spin exchange interactions are in general anisotropic, in a way similar to that encountered in magnetic materials involving spin-orbit coupling. For some topologies, we find that these active nanophotonic structures are governed by a classical XY Hamiltonian that exhibits two phases akin to those associated with ferromagnetic (FM) and antiferromagnetic (AF) materials. In addition, we show that in certain configurations, the electromagnetic field distribution can undergo geometrical frustration, depending on the lattice shape and the transverse resonant modes supported by the individual cavity elements. Our results could pave the way towards a new scalable nanophotonic platform to study spin exchange interactions, that can in turn be potentially exploited to investigate more large-scale networks, emulate some magnetic materials, or to address a variety of optimization problems.