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Entanglement Scaling and Spin Dynamics of the Heisenberg Bilayer

Stefan Wessel, RWTH Aachen

15.01.2016 at 09:00 

The spin-1/2 Heisenberg model on the square lattice bilayer provides a basic example to explore quantum critical behavior in quantum many-body systems. Its static equilibrium properties have been intensively investigated in the past, in contrast to, e.g., the modifications in the excitation spectrum across the quantum phase transition between the antiferromagnetically ordered phase and the quantum disordered regime. In this talk, results from quantum Monte Carlo simulations, combined with a stochastic analytic continuation approach are presented, which allow to track in detail the evolution the low-energy excitations related to Goldstone modes, as well as the longitudinal amplitude ("Higgs") mode in the ordered phase upon crossing the quantum critical point, and the corresponding restoration of the SU(2) symmetry in the disordered regime.
Employing the replica-trick, the evolution of the bipartite entanglement in terms of the second Renyi entropy has also been quantified. The dependence of the dominant area law contribution to the entanglement scaling on the interlayer coupling is analyzed, in particular its quantum critical enhancement. Sub-leading logarithmic terms due to Goldstone excitations and corner contributions will be discussed in view of their universal character.

A 450 - Theresienstr. 37