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A: Fachverband Atomphysik

A 4: Collisions, scattering and correlation phenomena I

A 4.2: Talk

Monday, February 29, 2016, 11:15–11:30, f107

Correlated reduced density operators of quantum lattice models — •Konstantin Krutitsky, Andreas Osterloh, and Ralf Schützhold — Fakultät für Physik der Universität Duisburg-Essen, Campus Duisburg, 47048 Duisburg

We present a systematic study of nonlocal correlations in quantum lattice models. With this purpose in mind we introduce correlated reduced density operators for arbitrary number of lattice sites q located at arbitrary distances from each other. Quantitative estimates of the nonlocal correlations are obtained calculating the Schatten p-norms of the correlated reduced density operators. For the Bose-Hubbard model in the case of unit filling, the Schatten norms with p=1 (trace norm) decrease with the number of sites q in the Mott-insulator phase and increase in the superfluid phase, while the norms with p=2 (Frobenius norm) decrease in both phases. For the transverse Ising model, the p=1 and p=2 norms decrease with the number of sites q in the disordered phase below the critical point. However, near and above the critical point the norms display a nonmonotonic behavior with respect to q. These results can be useful for the development of controlled approximations for the solution of quantum lattice models.