Teleportation of general quantum states, squeezing and the decoherence problem in quantum computers

In sections (1), (2) a channel theoretical formulation of the teleportation problem for quantum states, is given and a general solution, valid in arbitrary finite dimensions is proposed. The problem of uniqueness of the hidden key is discussed and a classification is obtained. The results in these sectionssurvey recent joint, work with Masanori Ohya. It is shown that the stochastic limit of quantum theory suggests the existence of two types of squeezingstates of the quantum EM field and correspondingly of two types of squeezing white noises. These states are stationary but usually non equilibrium states of the field and the stochastic limit evidentiates some qualitatively new phenomenon that arises in connection with these states. As a particular case we shall illustrate how one could take advantage of these new physical phenomena to prevent decoherence in quantum computers. The results in the second part of the paper survey recent joint work with S. Kozyrev, Y.G. Lu and I. Volovich.