  For the XXZ chain, we discuss the relation between a lattice version of Unruh
effect and the ground-state entanglement on the basis of the corner
Hamiltonian. We find that the lattice Unruh temperature is interpreted as
$\beta_\lambda = 2\pi/a$ with an effective acceleration $a=\pi/\lambda$, where
$\lambda$ denotes the anisotropy parameter of the XXZ chain. Using quantum
Monte Carlo simulation for the corner Hamiltonian at $\beta_\lambda$, we
demonstrate that world lines of spins surrounding the entangle point provides
an intuitive understanding the quantum entanglement. We also propose an
XXZ-chain analogue of the detector for the thermalized entanglement spectrum
with use of the angular time evolution defined by the corner Hamiltonian.
