Vanderstraeten Laurens, Mariën Michaël, Haegeman Jutho, Schuch Norbert, Vidal Julien, Verstraete Frank
Department of Physics and Astronomy, Ghent University, Krijgslaan 281, S9, 9000 Gent, Belgium.
Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany.
Phys Rev Lett. 2017 Aug 18;119(7):070401. doi: 10.1103/PhysRevLett.119.070401. Epub 2017 Aug 15.
We demonstrate that perturbative expansions for quantum many-body systems can be rephrased in terms of tensor networks, thereby providing a natural framework for interpolating perturbative expansions across a quantum phase transition. This approach leads to classes of tensor-network states parametrized by few parameters with a clear physical meaning, while still providing excellent variational energies. We also demonstrate how to construct perturbative expansions of the entanglement Hamiltonian, whose eigenvalues form the entanglement spectrum, and how the tensor-network approach gives rise to order parameters for topological phase transitions.
