Topological considerations in quantum theory

Summary

We consider the most general case of the restricted rigid rotor, controlled by passive mechanical devices located at θ=0 and θ=π. The purpose of these devices is to restrict the particle motion to a domain of a covering space (0,Mπ), whereM is an odd integer. This system, which is not a Hamiltonian one on the physical space (0, 2π), is compared with a Hamiltonian system having delta function barriers at θ=0 and θ=π. The case ofM an even integer is also discussed by using only one mechanical device at θ=0. This non-Hamiltonian system is compared with a Hamiltonian system having a delta function barrier at θ=0. It is shown that many of the wave functions of the non-Hamiltonian systems are the same as those of the Hamiltonian ones, with an average reflection coefficient of 1/(M+1) for oddM and 2/M for evenM, which are the classical values. We show how, in the case of very largeM, the superposition principle leads to de Broglie resonances.