Noiseless Linear Amplification and Loss-Tolerant Quantum Relay using Coherent State Superpositions

TL;DR

This paper introduces a scalable, loss-tolerant quantum relay capable of noiseless linear amplification on coherent states, enhancing quantum communication protocols and entanglement distillation with practical resource constraints.

Contribution

It presents a novel, scalable NLA scheme using coherent state superpositions, generalizing previous quantum scissors approaches and demonstrating loss-tolerance and utility in entanglement distillation.

Findings

Achieves perfect fidelity NLA on coherent states with finite resources.

Proves the NLA functions as a loss-tolerant relay for phase-shift keyed states.

Enhances continuous-variable entanglement distillation under realistic conditions.

Abstract

Noiseless linear amplification (NLA) is useful for a wide variety of quantum protocols. Here we propose a fully scalable amplifier which, for asymptotically large sizes, can perform perfect fidelity NLA on any quantum state. Given finite resources however, it is designed to perform perfect fidelity NLA on coherent states and their arbitrary superpositions. Our scheme is a generalisation of the multi-photon quantum scissor teleamplifier, which we implement using a coherent state superposition resource state. Furthermore, we prove our NLA is also a loss-tolerant relay for multi-ary phase-shift keyed coherent states. Finally, we demonstrate that our NLA is also useful for continuous-variable entanglement distillation, even with realistic experimental imperfections.