Frustrated Ising Model on D-wave Quantum Annealing Machine

The frustrated Ising model on a two-dimensional L ?? L square lattice with ferromagnetic (FM) nearest-neighbor and antiferromagnetic diagonal-neighbor interactions was studied by simulated annealing and quantum annealing on a Dwave advantage quantum annealing machine with 5000+ qubits composed on the Pegasus graph structure. A phase transition from FM to stripe order was found at the critical interaction, which was consistent with previous Monte Carlo and mean field results, through observations of the magnetization, energy, magnetic fluctuation, and structure factor. The results computed by the simulated and quantum annealing are in very good agreement. In addition, the probability of observing any magnetization at a given interaction in many quantum annealing shots was analyzed to estimate the complexity of an energy function. Finally, the limitations of the quantum annealing simulations resulting from the brokenness of qubits in chains, which we defined as the same variable on a D-wave advantage quantum annealing machine, were discussed.