Improving nonstoquastic quantum annealing with spin-reversal transformations
E. M. Lykiardopoulou, Alex Zucca, Sam A. Scivier, M. H. S. Amin · Physical Review A · 2021
Nonstoquastic Hamiltonians are hard to simulate due to the sign problem in quantum Monte Carlo simulation. It is, however, unclear whether nonstoquasticity can lead to advantage in quantum annealing. Here we show that $YY$ interactions between the qubits make the adiabatic path during quantum annealing, and therefore the performance, dependent on spin-reversal transformations. With the right choice of spin-reversal transformation, a nonstoquastic Hamiltonian with $YY$ interaction can outperform stoquastic Hamiltonians with similar parameters. We introduce an optimization protocol to determine the optimal transformation and discuss the effect of suboptimality.