Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 90: Low-Dimensional Systems: Topological Order 1 (jointly with DS, HL, MA, O)
TT 90.2: Vortrag
Donnerstag, 19. März 2015, 11:45–12:00, H 3010
Robustness of Symmetry Protected Topological Order in spin-2 quantum chains — •Augustine Kshetrimayum1, Hong-Hao Tu2, and Román Orús1 — 1Johannes Gutenberg University Mainz — 2MPQ Munich
Topological order is a new kind of order that cannot be described using the Landau theory. It is associated to a non-local pattern of entanglement. When such non-local properties are protected by specific symmetries, it is known as Symmetry Protected Topological Order.
The existence of such a symmetry protected topologically ordered Intermediate Haldane phase for a spin-2 Heisenberg chain was suggested by Oshikawa in 1992. However, the evidence for its existence has remained quite elusive. More recently, it has been proven that such a phase exists in a family of generalized spin-2 quantum Heisenberg chains.
In this work, we study the robustness of this phase for generalized spin-2 quantum Heisenberg chains with uni-axial anisotropy, and in the thermodynamic limit. We find very robust symmetry-protected topologically ordered SO(5)-Haldane and Intermediate-Haldane phases, which we assess by a variety of methods including the entanglement spectrum of the system and the behavior of string-order parameters. Moreover, we study time-evolution properties of these phases. Our numerical results are based on using Matrix Product States (MPS) to represent the wave function, in combination with the infinite Time-Evolving Block Decimation (iTEBD) method.