What is Quantum Annealing and quantum annealing computing and what are its advantages and disadvantages with respect to quantum circuit quantum computing/computers?
Quantum Annealing is a metaheuristic for finding the global minimum of a given objective function over a given set of candidate solutions (candidate states), by a process using quantum fluctuations.
It is more related to Adiabatic Quantum computing, which is regarded as subclass of quantum annealing.Compared to universal gate quantum computing which is much broader, Quantum annealing's use is limited.It is mainly used to solve optimization problem where the search space is discrete with many local minima; such as finding the ground state of a spin glass.
Quantum annealing harnesses the natural evolution of quantum states:the system is initialized in a delocalized state, we gradually turn on the description of the problem we wish to solve, and quantum physics allows the system to follow these changes. The configuration at the end corresponds to the answer we are trying to find.Currently D-wave is using this approach to solve such problems.