  An interesting analogy between quantum entangled states and topological links
was suggested by Aravind. In particular, he emphasized a connection between the
Greenberger-Horne-Zeilinger (GHZ) state and the Borromean rings. However, he
made the connection in a way that depends on the choice of measurement basis.
We reconsider it in a basis-independent way by using the reduced density
matrix.
