Theoretical survey of unconventional quantum annealing methods applied to a difficult trial problem*

Adiabatic quantum annealing is a promising method to solve optimization problems. In our work, we define an artificial trial problem inspired by "transverse field chaos" in larger systems where classical and quantum methods are steered toward a local false minimum and the minimum gap to the true ground state is exponentially small. (all N spins must be flipped from the local minimum to the global minimum, which makes the problem exponentially difficult to solve.) We numerically study this problem by using a variety of new methods from the literature: ramping the transverse field down one by one; adding transverse couplers between qubits; adding local oscillating transverse field. We show that the standard adiabatic quantum annealing method can be improved with these methods, and comparison of these methods could help identify the most promising routes to a quantum speedup in future quantum hardware.