31. One can view " ? " ? as a density matrix , and therefore the state dual to ?. 32. The compression can be described as a sort operation on the diagonal entries of the density matrix which describes the system. 33. However, the general form of the compression operation is a sort operation on the diagonal entries of the density matrix . 34. However, in contrast to Lindblad equations, Redfield equations do not guarantee a positive time evolution of the density matrix . 35. Let ? be a density matrix acting on a Hilbert space H _ A of finite dimension " n ". 36. In 1981, Bohm and Hiley introduced the " characteristic matrix ", a non-Hermitian extension of the density matrix . 37. HEOMs are developed to describe the time evolution of the density matrix \ rho ( t ) for an open quantum system. 38. The Renyi entropy in quantum physics is not considered to be an observable, due to its nonlinear dependence on the density matrix . 39. Bayesian methods as well as Maximum likelihood estimation of the density matrix can be used to restrict the operators to valid physical results. 40. In quantum statistical mechanics, the ensemble is a probability distribution over pure states, and can be compactly summarized as a density matrix .
