Pathways for entanglement based quantum communication in the face of high noise

TL;DR

This paper demonstrates that high-dimensional entanglement in spatial paths enhances noise resistance in quantum key distribution, enabling secure communication over noisier channels than qubit-based schemes.

Contribution

It shows practical QKD using eight entangled paths that maintains secure key rates despite high environmental noise, surpassing qubit-based limitations.

Findings

Key rates exceed 1 bit per photon pair after error correction.

Secure keys are certified at noise levels prohibitive for qubit schemes.

High-dimensional entanglement improves noise robustness in quantum communication.

Abstract

Entanglement based quantum communication offers an increased level of security in practical secret shared key distribution. One of the fundamental principles enabling this security -- the fact that interfering with one photon will destroy entanglement and thus be detectable -- is also the greatest obstacle. Random encounters of traveling photons, losses and technical imperfections make noise an inevitable part of any quantum communication scheme, severely limiting distance, key rate and environmental conditions in which QKD can be employed. Using photons entangled in their spatial degree of freedom, we show that the increased noise resistance of high-dimensional entanglement, can indeed be harnessed for practical key distribution schemes. We perform quantum key distribution in eight entangled paths at various levels of environmental noise and show key rates that, even after error correction and privacy amplification, still exceed $1$ bit per photon pair and furthermore certify a secure key at noise levels that would prohibit comparable qubit based schemes from working.