Hams and Raedt gave a quantum computational algorithm to calculate the density of states of a spin system. Starting with an initial random state, they obtain the time evolution of the state. Later they take the inner product of the evolved state with the initial state. How does the inner...
In many books and also in wikipedia, the Trace of a matrix is defined as sum of its diagonal elements. For a general matrix, it does not make much sense, as any element is as important any other element. An alternative definition (in wikipedia for example) is that the Trace of the matrix...