Düsseldorf 2007 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 34: Poster Quanteninformation

Q 34.12: Poster

Dienstag, 20. März 2007, 16:30–18:30, Poster C

Entanglement of Collectively Interacting Harmonic Strings — •Razmik Unanyan¹, Michael Fleischhauer², and Dagmar Bruß¹ — ¹Theoretische Physik III, Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf — ²Fachbereich Physik, Technische Universität Kaiserslautern, 67663, Kaiserslautern

We study the ground-state entanglement of one-dimensional harmonic strings that are coupled to each other by a collective interaction as realized e.g. in an anisotropic ion crystal. Due to the collective type of coupling, where each string interacts with every other one in the same way, the total hamiltonian has a vanishing energy gap and thus shows critical behavior even though the isolated harmonic strings are gapped and thus non-critical. We derive lower and upper bounds for the entanglement, quantified by the von Neumann entropy, between a compact block of oscillators and its environment. For sufficiently large size of subsystems the bounds coincide and show that the area law for entanglement is violated by a logarithmic correction.