Quantum communications and measurement

Аннотация

An introduction is given to the stationary theory of quantum stochastic processes of second order, which includes KMS processes like the equilibrium finite temperature quantum noise given by the Planck spectral formula. It is shown that for each stationary noise there exists a natural output process which is identical to the noise in the infinite temperature limit, and flipping with the noise if the time is reversed at finite temperature. A canonical Hilbert space representation of the quantum noise and the fundamental output process is established and a decomposition of their spectra is found.