How accurately can the microcanonical ensemble describe small isolated quantum systems?
Tatsuhiko N. Ikeda, Masahito Ueda
We numerically investigate quantum quenches of a nonintegrable hard-core Bose-Hubbard model to test the accuracy of the microcanonical ensemble in small isolated quantum systems. We show that, in a certain range of system size, the accuracy increases with the dimension of the Hilbert space D as 1/D. We ascribe this rapid improvement to the absence of correlations between many-body energy eigenstates. Outside of that range, the accuracy is found to scale either as 1/√D or algebraically with the system size.
arXiv:1503.07974•Physical Review E•Aug 5, 2015•25 citations