Beyond Standard Quantum Annealing

Quantum annealing is typically studied (and experimentally realized) in terms of an interpolation between a driver and a problem Hamiltonian, often taken to be a uniform transverse field and an Ising Hamiltonian respectively. Nothing restricts the time-dependent Hamiltonian to take such a simple form, and greater control of experimental systems has revived the study of more exotic interpolations. We review recent work exploring new quantum annealing protocols, including adiabatic reverse annealing and the introduction of catalyst Hamiltonians. While providing an exponential improvement in performance for solving certain highly symmetric toy models, no recipe is known for how to use these new proposals to give performance enhancements more generally. This highlights the need for dramatically new insights and methods but also more experimental capabilities to further explore the performance of non-standard quantum annealing.