appConfigEntityId

bodyType

customContents

entityId

entityUuid

isVideo

articlePageQuery

article

articleSchemaContent

content

hooksArticlePageAdvertisementConfigArticle

hooksArticlePageFloatingButtonConfigArticle

appConfig

filter

json

liveArticle

Dannie Peng

Chinese scientists have achieved the quantum entanglement of cold atoms across a record-breaking 420km (260 miles), a breakthrough they say lays the groundwork for intercity quantum networks.
According to a paper published by the peer-reviewed journal Physical Review Letters on August 11, the distance was more than four times previous demonstrations and exceeded the threshold at which direct transmission encounters fundamental physical limits.
“Our experiment provides a test bed for studying quantum-network applications beyond the metropolitan scale,” said the team of physicists, who included Pan Jianwei from the University of Science and Technology of China in Hefei, Anhui province.
The researchers used two quantum memory units, each consisting of laser-cooled clouds of rubidium atoms, 420km apart and connected by an optical fibre link.
The aim was to achieve entanglement – the phenomenon in which two or more particles – often photons – become inextricably linked, sharing a joint quantum state regardless of the physical distance between them.


While scientists have previously succeeded in entangling light particles across vast stretches of empty space and through optical fibre, introducing quantum memory into the equation makes the process more complex.
Long-distance entanglement will be crucial if widely separated quantum systems are to share information and coordinate operations, providing the foundation for scalable quantum communications, computing and networked sensing.
However, sending fragile quantum signals over long stretches of optical fibre inevitably leads to severe signal loss. To construct wide-area networks, scientists must rely on memory devices to store the signals, allowing them to be distributed in segments.
Even the slightest changes in temperature or mechanical vibration can disrupt the delicate quantum interference required to produce entanglement. The team used several sophisticated techniques to overcome these challenges.
To minimise external interference, the researchers developed a system that continuously corrected for fluctuations, keeping the quantum states synchronised across the entire link, the paper said.
The team also adjusted the operating wavelength of the quantum memory units, enabling the signals to travel through the fibre-optic cable with significantly reduced transmission losses.
The study exceeded an established principle in physics that, without repeaters or memory devices, there is a cap on the amount of quantum data that can survive the constraints of a lossy communication channel with its distortions and degraded signals.
The team showed that its system could achieve entanglement beyond 320km – exceeding the theoretical maximum for sending a direct signal over a stretch of fibre.
This latest milestone builds upon several years of research by Pan and his team, who in 2020 successfully showed entanglement between two quantum memory units across 50km of optical fibre.
Quantum frontier advances
Building on that foundation, the researchers established the world’s first three-node network in 2024.
In February this year, another team led by Pan advanced the frontiers of quantum encryption by sending secure information over more than 100km of fibre-optic cable without needing to trust the security of the devices being used.
The experiment was detailed in a paper published by Science. The researchers used two individual rubidium atoms trapped in laser beams at separate network nodes as the basis of their system.
Passionate about science? Dive deeper with the Dark Matters newsletter, a weekly in-depth analysis on China’s rise in science, technology and military that goes beneath the surface. Sign up for free now.


Chinese scientists build world’s smallest CT scanner, weighing just 6kg

China mulls building nuclear-powered tank with 450km-range railgun in 2 decades

Top Singaporean chemist Lu Yixin to join Chinese university EIT next year

Chinese plant extracts critical rare metals from lithium waste in world first

Science

Miles ahead: China team boosts atom entanglement distance record fourfold

Chinese physicist Pan Jianwei and his team say their experiment provides a test bed for studying quantum network applications beyond the metropolitan scale. Photo: Shutterstock

China’s political and scientific elite head to Beidaihe for summer retreat season

Cai Qi greets researchers and academics at Beidaihe. Photo: CCTV

China is sending scientists to Iran for rare earth ‘exploration and processing’

A display of rare earth elements at the National Museum in Beijing. China holds the largest reserves of the metals in the world. Photo: Reuters

Chinese ‘yeast factory’ boosts cancer drug production by 1,000 times

Researchers have engineered brewer’s yeast to produce catharanthine – the direct precursor to the cancer treatment vinblastine. Photo: Getty Images/iStockphoto

The anticancer drug vinblastine has long been sourced exclusively from the Madagascar periwinkle (Catharanthus roseus) plant. Photo: Shutterstock

China’s STEM students turn to Singapore as Western study options shrink

Illustration: Quoc Huy Truong


The National University of Singapore is among the city state’s universities vying to attract the brightest Chinese STEM students. Photo: Handout

US President Donald Trump looks on as he signs executive orders and proclamations in the Oval Office at the White House, in May 2025. Photo: Reuters

Singapore is emerging as a regional hub for science and technology, boosted by scholarship schemes that draw Chinese students into its universities. Photo: AFP

News

China

The breakthrough is expected to provide a foundation for scalable quantum communications, computing and networked sensing


The breakthrough is expected to provide a foundation for scalable quantum communications, computing and networked sensing.


Pan Jianwei

University of Science and Technology of China

Miles ahead: China team boosts atom entanglement distance record fourfold

.css-1c6uqr6{color:inherit;font-weight:inherit;font-size:inherit;font-family:inherit;line-height:inherit;overflow-wrap:break-word;}The breakthrough is expected to provide a foundation for scalable quantum communications, computing and networked sensing

The breakthrough is expected to provide a foundation for scalable quantum communications, computing and networked sensing