# Entanglement Spectroscopy of SU(2)-Broken Phases in Two Dimensions

**When:**Tuesday, March 18, 2014 at 2:30 pm

**Where:**DA 114

**Speaker**: Vincenzo Alba

**Organization**: Ludwig-Maximilians-Universitat Munchen

**Sponsor**: Condensed Matter Seminar

In magnetically ordered systems the breaking of SU(2) symmetry in the thermodynamic limit is associated with the appearance of a special type of low-lying excitations in finite size energy spectra, the so-called tower of states (TOS). In this talk I will provide numerical evidence that there is a correspondence between the SU(2) tower of states and the lower part of the ground state entanglement spectrum (ES). In particular, I will present state-of-the-art DMRG calculations for the 2D antiferromagnetic J1-J2 Heisenberg model on both the triangular and kagome lattice. At large ferromagnetic J2 the model exhibits a magnetically ordered ground state. Correspondingly, its ES contains a family of low-lying levels that are reminiscent of the energy tower of states. Their behavior (level counting, finite size scaling in the thermodynamic limit) sharply reflects tower of states features, and is characterized in terms of an effective entanglement Hamiltonian. At large system sizes TOS levels are divided from the rest by an entanglement gap.

Host: Assistant Professor Adrian Feiguin