  We show that the recently proposed scheme of teleportation of continuous
variables [S.L. Braunstein and H.J. Kimble, Phys. Rev. Lett. 80, 869 (1998)]
can be improved by a conditional measurement in the preparation of the
entangled state shared by the sender and the recipient. The conditional
measurement subtracts photons from the original entangled two-mode squeezed
vacuum, by transmitting each mode through a low-reflectivity beam splitter and
performing a joint photon-number measurement on the reflected beams. In this
way the degree of entanglement of the shared state is increased and so is the
fidelity of the teleported state.
