Radiation-induced reduction of a wave packet in a magnetic field

An original Heisenberg-picture approach to a Brownian motion of wave packets in a dissipative environment is developed. We study an influence of an external magnetic field on quantum interference of two Gaussian wave packets as well as on the dynamics of decoherence due to coupling of the charge particle to a blackbody radiation (BBR) heat bath. It is shown that the Gaussian wave packet may be individually considered as a squeezed state with super-Poissonian statistics of excitations. We find that in the presence of the constant uniform magnetic field the interaction with the classical BBR heat bath serves as a very efficient mechanism for the destruction of interference terms and the transition from quantum to classical behavior. Special features of wave packet spreading and reduction stemming from the non-white nature of the noise from the classical BBR heat bath are discussed.