Annealing in the Noisy Intermediate-Scale Quantum Era: Key concepts and approaches

In the noisy intermediate-scale quantum (NISQ) era, annealing-based computing is emerging as a new type of high-performance computing (HPC) technology for solving computationally intractable combinatorial optimization problems (COPs). Inspired by thermal annealing in metallurgy, the cost function of a COP is encoded in an energy function (Hamiltonian), with its lowest energy state being searched using an annealer and finally transformed to the global or global approximate optimal solution to a target problem. We address the key technology underlying annealing-based methods along with an experimental study with a commercial digital annealer (DA). We hope to shed light on how industries could benefit from this emerging computing technology to explore the challenges and opportunities in the quantum computing age.