Teleportation-based noiseless quantum amplification of coherent states of light

Abstract

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 teleamplifier.

Ideal Quantum Tele-amplification up to a Selected Energy Cut-off using Linear Optics

“…Finally, we showed that a distributed n-QS quantum relay is loss-tolerant with fast rates, hence is useful as building blocks for quantum repeater networks. Note added.-The authors recently became aware of a new related work which investigated noiseless quantum tele-amplifiers from a different angle [52], based on the continuous-variable teleportation protocol [35].…”