Quantum tele-amplification with a continuous variable superposition state

TL;DR

This paper demonstrates quantum tele-amplification using optical cat states, enabling coherent state teleportation with amplitude gain and loss-tolerant quantum relays, advancing quantum communication capabilities.

Contribution

It introduces a protocol for quantum tele-amplification with continuous variable superposition states, extending the use of optical cat states in quantum communication.

Findings

Successfully teleport coherent states with amplitude gain

Implemented a loss-tolerant quantum relay for phase-shift keyed states

Demonstrated feasibility of quantum protocols using optical cat states

Abstract

Optical coherent states are classical light fields with high purity, and are essential carriers of information in optical networks. If these states could be controlled in the quantum regime, allowing for their quantum superposition (referred to as a Schr\"odinger cat state), then novel quantum-enhanced functions such as coherent-state quantum computing (CSQC), quantum metrology, and a quantum repeater could be realized in the networks. Optical cat states are now routinely generated in the laboratories. An important next challenge is to use them for implementing the aforementioned functions. Here we demonstrate a basic CSQC protocol, where a cat state is used as an entanglement resource for teleporting a coherent state with an amplitude gain. We also show how this can be extended to a loss-tolerant quantum relay of multi-ary phase-shift keyed coherent states. These protocols could be useful both in optical and quantum communications.