Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 88: Quantum-Critical Phenomena III

TT 88.4: Talk

Thursday, March 15, 2018, 12:15–12:30, H 3010

Avalanche of entanglement and correlations at quantum phase transitions — •Andreas Osterloh, Konstantin V. Krutitsky, and Ralf Schützhold — Universität Duisburg-Essen, Duisburg, Deutschland

We study the two, three, and four-point correlations in the ground-state of the quantum Ising model in a transverse field with nearest neighbor ferromagnetic coupling J and find a partial inversion of their hierarchy. Namely, the four-point correlation exceeds the three- and two-point correlations, well before the critical point is reached. Qualitatively similar behavior is also found for the Bose-Hubbard model, suggesting this change in hierarchy to be a general feature of a quantum phase transition. It should be taken into account in approximations starting from a mean-field limit.

In addition, we find a sequential increase of entanglement depth d with growing J, hence an avalanche that starts with two-point entanglement, as measured by the concurrence, and continues via the three-tangle and four-tangle, until finally, deep in the ferromagnetic phase for J=∞, the exact model would arrive at a pure L-partite (GHZ type) entanglement of all L spins.