Our criteria for continuous variable quantum teleportation [T.C.Ralph and
P.K.Lam, Phys.Rev.Lett. {\bf 81}, 5668 (1998)] take the form of sums, rather
than products, of conjugate quadrature measurements of the signal transfer
coefficients and the covariances between the input and output states. We
discuss why they have this form. We also discuss the physical significance of
the covariance inequality.Comment: 6 pages, to appear in Lecture Notes in Physics; Dan Walls Memorial
Volume (Springer 2000
