Symmetry-protected topological order in SU(N) Heisenberg magnets --quantum entanglement and non-local order parameters

Understand

In this paper, we investigate topological properties of the ground state of the SU(N) Heisenberg chain, which is argued to be relevant to the Mott-insulating phase of alkaline-earth cold fermions in a one-dimensional optical lattice.

• By calculating the entanglement spectrum, we show that the ground state is in one of the topological phases protected by SU(N) symmetry.
• We then discuss an alternative characterization of it with non-local string order parameters.
• We also consider how the reduction of the protecting symmetry affects the topological phase paying particular attention to the entanglement spectrum.