Byers-Yang_theorem
Byers–Yang theorem
Theorem in quantum mechanics
In quantum mechanics, the Byers–Yang theorem states that all physical properties of a doubly connected system (an annulus) enclosing a magnetic flux through the opening are periodic in the flux with period (the magnetic flux quantum). The theorem was first stated and proven by Nina Byers and Chen-Ning Yang (1961),[1] and further developed by Felix Bloch (1970).[2]