  A parametric amplifier is in essence a linear four-port device, which couples
and linearly mixes two inputs before amplifying and sending them to two output
ports. Here, we show that for quadrature-phase amplitudes, a parametric
amplifier can replace beam splitters to play the role of mixer. We apply this
idea to a continuous-variable quantum state teleportation scheme in which a
parametric amplifier replaces a beam splitter in Bell measurement. We show that
this scheme is loss-tolerant in the Bell measurement process and thus
demonstrate the advantage of PA over BS in the applications in quantum
measurement.
