Quantum repeater via entangled phase modulated multimode coherent states

TL;DR

This paper proposes a quantum repeater scheme using entangled multimode coherent states generated by electro-optic modulation, enabling extended quantum communication range through heralded entanglement and teleportation.

Contribution

It introduces a novel method of creating entangled multimode coherent states via phase modulation of Schrödinger cat states for quantum repeaters.

Findings

Decoherence impacts photocount statistics and fidelity.

Heralded entanglement can be used to extend quantum key distribution.

The scheme facilitates quantum teleportation with generated entanglement.

Abstract

We present a scheme of quantum repeater that uses entangled multimode coherent states which are obtained by electro-optic modulation of symmetric and antisymmetric Schr\"odinger cat states. In this method subcarrier modes of the phase modulated states generated by the remote parties are sent to a symmetric beam splitter at the central node. The entangled coherent states are heraldedly prepared by photon counting measurements at the output channels of the beam splitter. We study how the effects of decoherence in the quantum channel affect statistics of photocounts and corresponding fidelity. We show how the proposed scheme can be useful for extending range of quantum key distribution with sub carrier wave encoding by exploiting quantum teleportation with the generated entanglement.