Hannover 2010 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 55: Poster II

Q 55.64: Poster

Donnerstag, 11. März 2010, 16:00–19:00, Lichthof

Short-time vs. long-time dynamics of entanglement in quantum lattice models — •Razmik Unanyan, Dominik Muth, and Michael Fleischhauer — Fachbereich Physik und Forschungszentrum OPTIMAS, Technische Universität Kaiserslautern

We study the short-time evolution of the bipartite entanglement in quantum lattice systems with local interactions in terms of the purity of the reduced density matrix. A lower bound for the purity is derived in terms of the eigenvalue spread of the interaction Hamiltonian between the partitions. Starting from an initially separable state the purity decreases as 1 − (t/τ)², i.e. quadratically in time, with a characteristic time scale τ that is inversly proportional to the boundary size of the subsystem, i.e., as an area–law. For larger times an exponential lower bound is derived corresponding to the well-known linear-in-time bound of the entanglement entropy. The validity of the derived lower bound is illustrated by comparison to the exact dynamics of a 1D spin lattice system as well as a pair of coupled spin ladders obtained from numerical simulations.