A de Finetti representation for finite symmetric quantum states
arXiv:quant-ph/0410229 · doi:10.1063/1.2146188
Abstract
Consider a symmetric quantum state on an n-fold product space, that is, the state is invariant under permutations of the n subsystems. We show that, conditioned on the outcomes of an informationally complete measurement applied to a number of subsystems, the state in the remaining subsystems is close to having product form. This immediately generalizes the so-called de Finetti representation to the case of finite symmetric quantum states.
22 pages, LaTeX