Stuttgart 2012 – wissenschaftliches Programm
Q 25.1: Vortrag
Dienstag, 13. März 2012, 10:30–10:45, V7.01
Exponential families of quantum states — •Sönke Niekamp1, Tobias Galla2, and Otfried Gühne1 — 1Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Walter-Flex-Str. 3, D-57068 Siegen — 2Complex Systems and Statistical Physics Group, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
Exponential families provide a classification of multipartite quantum states according to their correlations. In this classification scheme, a state is considered as k-correlated if it can be written as thermal state of a Hamiltonian containing interactions between at most k parties. The distance of a state to an exponential family in terms of the relative entropy has been suggested as a correlation measure. The corresponding classical quantities have found application in the study of complex dynamical systems.
We present an efficient algorithm for the computation of the nearest k-correlated state (the information projection) of a given quantum state. In analogy to the task of entanglement detection, we consider witness operators which can be used to prove that an experimental state contains higher-order correlations. This is related to the question if certain relevant quantum states (such as cluster states) can be approximated by ground states of two-body Hamiltonians.