  We study the angular-time evolution that is a parameter-time evolution
defined by the entanglement Hamiltonian for the bipartitioned ground state of
the Affleck-Kennedy-Lieb-Tasaki (AKLT) chain with the open boundary. In
particular, we analytically calculate angular-time spin correlation functions
$\langle S_n^\alpha(\tau)S_n^\alpha(0)\rangle$ with $\alpha = x,y,z$, using the
matrix-product-state (MPS) representation of the valence-bond-solid state with
edges. We also investigate how the angular-time evolution operator can be
represented in the physical spin space with the use of gauge transformation for
the MPS. We then discuss the physical interpretation of the angular-time
evolution in the AKLT chain.
