Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 24: Correlated Electrons: Low-dimensional Systems - Models
TT 24.16: Vortrag
Mittwoch, 27. Februar 2008, 18:15–18:30, H 2053
Entanglement percolation at quantum phase transitions in random quantum magnets — •Yu-Cheng Lin1, Ferenc Igloi2,3, and Heiko Rieger1 — 1Theoretische Physik, Universität des Saarlandes, 66041 Saarbrücken, Germany — 2Research Institute for Solid State Physics and Optics, H-1525 Budapest, Hungary — 3Institute of Theoretical Physics, Szeged University, H-6720 Szeged, Hungary
We study the scaling of the entropy quantifying the degree of quantum entanglement between two regions in a bipartite random quantum Ising model in two dimensions, using an asymptotically exact renormalization group treatment [1]. This system undergoes a quantum phase transition at a certain transverse field strength, at which point the von Neumann entanglement entropy of a subsystem violates the "area law", providing evidence for non-trivial and long-range quantum entanglement in the ground state. The entanglement entropy per surface area of a subsystem diverges in a double logarithmic form, arising from a type of percolation of the critical ground state that is fundamentally different from classical percolation. The latter can be found in an analogous quantum system with random bond dilution; here the area law is valid at the quantum critical point, which implies that entanglement cannot be regarded as an indicator of quantum criticality for higher dimensional systems in the way as for one-dimensional cases.
[1] Y.-C. Lin, F. Iglói and H. Rieger, Phys. Rev. Lett. 99, 147202 (2007).