Dynamic and Ergodic Properties of the XY-Model

摘要: In quantum mechanics, a physical observable is described by (linear) operator Q on Hilbert space H and (pure) state unit vector Ψ in H. The expectation value (the average of measured values for large number repeated measurements) the State given (1.1.1) More general states called mixtures are positive ρ trace 1, density matrix, which (1.1.2) and at most countable sum form (1.1.1). ((1.1.1) special case where one-dimensional projection operator.)