Both reduction in computational load and setting parameters with ease are necessary in calculation of global optimization. For this we propose a new quantum mechanical method of the problem. Global optimization is achieved by a quantum particle with energy dissipation due to frictional force. Canonical quantization is applied to a system that consists of one mass point under friction proportional to its velocity. Realistic motion of a particle is abstracted from a resultant quantum system according to a causal interpretation. By simulation of the quantum particle motion under potential functions V(x) with local minima and one global minimum, it is clarified that the particle with its initial position at the local minimum at rest necessarily arrives at the global minimum. Only one particle is needed in the new algorithm. When we clarify mathematical structure of our algorithm, difficulties found in quantum annealing or conventional method for global optimization will thereby be solved in the new method.
The non-local boundary condition introduced by Bogolyubov et al. is useful for eliminating the difficulty of negative probability concerning the indefinite metric in Hilbert space. Their theory is developed in the S-matrix formalism and does not give a causal description of the physical state. A causal description is given here in the form of an ordinary Schrödinger equation. The Hamiltonian is not hermitian in general, though it gives the unitary S-matrix. Such a characteristic situation is discussed by using a simple model.