  We propose and theoretically analyze a teleportation-based scheme for
high-fidelity noiseless quantum amplification of coherent states of light. In
our approach, the probabilistic noiseless quantum amplification operation is
encoded into a suitable auxiliary two-mode entangled state and then applied to
the input coherent state via continuous-variable quantum teleportation. The
scheme requires conditioning on the outcomes of homodyne measurements in the
teleportation protocol. In contrast to high-fidelity noiseless quantum
amplifiers based on combination of conditional single-photon addition and
subtraction, the present scheme requires only photon subtraction in combination
with auxiliary Gaussian squeezed vacuum states. We first provide a pure-state
description of the protocol which allows us to to clearly explain its
principles and functioning. Next we develop a more comprehensive model based on
phase-space representation of quantum states, that accounts for various
experimental imperfections such as excess noise in the auxiliary squeezed
states or limited efficiency of the single-photon detectors that can only
distinguish the presence or absence of photons. We present and analyze
predictions of this phase-space model of the noiseless tele-amplifier.
