High Quality Content by WIKIPEDIA articles! In the most general form, the dynamics of a quantum-mechanical system are determined by a master equation - an equation of motion for the density operator (usually written ) of the system. Although it is possible to directly integrate this equation for very small systems (i.e., systems with few particles or degrees of freedom), this quickly becomes impossible for larger systems. For this reason, it is frequently useful to represent the density operator as a distribution over some (over-)complete operator basis. The evolution of the system is then completely determined by the evolution of a quasi-probability distribution function. This general technique has a long history, especially in the context of quantum optics. The most common examples of quasi-probability representations are the Wigner, P- and Q-functions. More recently, the positive P function and a wider class of generalized P functions have been used to solve complex problems in both quantum optics and the newer field of quantum atom optics.

Данное издание не является оригинальным. Книга печатается по технологии принт-он-деманд после получения заказа.