1. A method of minimizing an objective including a set of weights and a dictionary, the method comprising: casting the set of weights in the objective as Boolean variables using a digital processor; setting a first set of values for the dictionary using the digital processor; optimizing the objective for a first set of values for the Boolean weights based on the first set of values for the dictionary, wherein optimizing the objective for a first set of values for the Boolean weights includes mapping the objective to a first quadratic unconstrained binary optimization (“QUBO”) problem and using a quantum processor to at least approximately minimize the first QUBO problem; optimizing the objective for a second set of values for the dictionary based on the first set of values for the Boolean weights, wherein optimizing the objective for a second set of values for the dictionary includes using a non-quantum processor to update at least some of the values for the dictionary; optimizing the objective for a second set of values for the Boolean weights based on the second set of values for the dictionary, wherein optimizing the objective for a second set of values for the Boolean weights includes mapping the objective to a second QUBO problem and using the quantum processor to at least approximately minimize the second QUBO problem; and optimizing the objective for a third set of values for the dictionary based on the second set of values for the Boolean weights, wherein optimizing the objective for a third set of values for the dictionary includes using the non-quantum processor to update at least some of the values for the dictionary.