Topological disentangler for the valence-bond-solid chain

Understand

We discuss topological disentangler for S=1 quantum spin chains in the Haldane phase.

• We first point out that Kennedy-Tasaki's(KT) nonlocal unitary transformation is the perfect disentangler for Affleck-Kennedy-Lieb-Tasaki model.
• We then demonstrate that the KT transformation can be reconstructed as an assembly of pair disentanglers.
• Finally, we show that the KT transformation can be regarded as a topological disentangler, which selectively disentangles the double-fold degeneracy in the entanglement spectrum of the S=1 Heisenberg chain.