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TT: Fachverband Tiefe Temperaturen

TT 4: Low-Dimensional Systems: 1D - Theory

TT 4.10: Vortrag

Montag, 31. März 2014, 12:00–12:15, HSZ 201

Entanglement entropies for interacting many-fermion systems — •Peter Bröcker and Simon Trebst — Institute for Theoretical Physics, University of Cologne, Germany

The precise determination of the entanglement of an interacting quantum many-body systems is now appreciated as an indispensable tool to identify the fundamental character of the ground state of such systems. This is particularly true for unconventional ground states harboring non-local topological order or so-called quantum spin liquids that evade a standard description in terms of correlation functions.

With the entanglement entropy emerging as one of the central measures of entanglement, recent progress has focused on a precise characterization of its scaling behavior, in particular in the determination of (subleading) corrections to the prevalent boundary-law. While much progress has been made for spin and bosonic quantum many-body systems, fermion systems have proved to be more difficult.

For a large class of interacting fermionic systems, the numerical method of choice for unbiased, large-scale simulations is Determinantal Quantum Monte Carlo (DQMC) for which a generalization of the replica techniques developed to calculate entanglement entropies for spin and bosonic systems has remained an open question. Here we show one possibility how to construct the corresponding algorithm in DQMC and demonstrate its strength by studying the thermal crossover of the entanglement entropy in one-dimensional Hubbard systems. We also compare our results to another recent approach based on free fermion Green’s functions.