China Team Extends Atom Entanglement to 420 km, Beating Prior Record More Than Fourfold
Updated
Updated · South China Morning Post · Aug 14
China Team Extends Atom Entanglement to 420 km, Beating Prior Record More Than Fourfold
3 articles · Updated · South China Morning Post · Aug 14
Summary
A China-based research team entangled two quantum memory units 420 km apart through an optical-fibre link, setting a new atom entanglement distance record.
The result, reported August 11 in Physical Review Letters, was more than four times farther than previous demonstrations and crossed the range where direct transmission faces fundamental physical limits.
The experiment used two quantum memories made from laser-cooled clouds of rubidium atoms, adding complexity beyond earlier long-distance entanglement work focused mainly on photons.
That advance is expected to underpin scalable quantum communications, quantum computing and networked sensing by showing quantum memory can work across much longer fibre distances.
If the quantum memories never left the lab, what does a 420-kilometer entanglement record really mean for the future quantum internet?
Could converting fragile quantum signals to telecom wavelengths be the secret to finally building a hack-proof global communications network?
Building the Quantum Internet: Technical Milestones, Global Competition, and Security Challenges to 2030
Overview
This report explores the technical and security challenges of building quantum networks and the global race for quantum supremacy. It highlights how fragile quantum states in memories can be disrupted by tiny environmental changes, such as temperature shifts or minute changes in photon paths, which can destroy entanglement. To address these issues, researchers use quantum frequency conversion and wavelength engineering to allow quantum and classical signals to coexist in fiber networks, mitigating noise from inelastic scattering. However, the lack of practical quantum repeaters remains a major bottleneck for long-distance quantum internet. On the security front, the looming threat of quantum computers breaking current cryptography drives urgent migration to quantum-safe systems, with regulatory deadlines pushing industries to prove their preparedness. The report also notes that while Quantum Key Distribution offers strong security, it is resource-intensive and not suitable for widespread deployment, and that high costs and budget constraints slow the transition to quantum-safe infrastructure.