Teleportation-based noiseless quantum amplification of coherent states of light

TL;DR

This paper introduces a teleportation-based scheme for noiseless quantum amplification of coherent light states, achieving high fidelity by using entangled states and homodyne measurements, with analysis of experimental imperfections.

Contribution

It presents a novel teleportation-based protocol for noiseless amplification that simplifies previous methods by using photon subtraction and Gaussian states, with detailed theoretical modeling.

Findings

The scheme enables high-fidelity noiseless amplification of coherent states.

Theoretical analysis includes effects of experimental imperfections.

The protocol is feasible with current quantum optics technology.

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 tele-amplifier.