A new approach to quantum statistical thermodynamics

A new approach to quantum statistical thermodynamics is presented; this is based on Einstein's distinction between the stationary state functions of single systems and the superposed state function relevant to a statistical assembly of systems, and on the relative frequency interpretation of the theory of probability. This approach is free from Gibbs' concept of ensemble, the ergodic hypothesis, the assumptions of equal a priori probabilities and random a priori phases, and von Neumann's concept of density matrix.