USTC's Groundbreaking Quantum Repeater Demonstration
The University of Science and Technology of China (USTC) has marked a pivotal moment in quantum physics with its latest achievement in scalable quantum networks. Researchers from USTC, led by renowned physicist Jian-Wei Pan, have demonstrated the world's first scalable building block for quantum repeaters. This innovation addresses a long-standing challenge in quantum communication: extending entanglement over distances where optical fiber losses typically destroy quantum states.
Published in Nature on February 11, 2026, the paper titled "Long-lived remote ion–ion entanglement for scalable quantum repeaters" details how the team achieved memory-memory entanglement between two nodes connected by 10 kilometers of spooled fiber. The entanglement survived longer than the average time required to establish it, a critical threshold for practical quantum repeaters.
Understanding Quantum Communication Challenges
Quantum communication relies on entanglement, a phenomenon where particles remain correlated regardless of distance, enabling ultra-secure key distribution via quantum key distribution (QKD). However, photons traveling through optical fibers suffer exponential loss, limiting entanglement distribution to short distances—typically under 100 kilometers without repeaters.
Traditional solutions like trusted nodes introduce security vulnerabilities, while quantum repeaters—using quantum memories to store and swap entanglement—have been theoretical due to decoherence outpacing establishment times. USTC's advance uses trapped-ion quantum memories, which store quantum information in the electronic states of ions trapped by electromagnetic fields, offering coherence times orders of magnitude longer than previous systems.
USTC's Legacy in Quantum Research
USTC, located in Hefei, Anhui Province, is a powerhouse in quantum science, consistently ranking among China's top institutions for physics and information technology. Under Pan Jianwei, who serves as executive vice president and a Chinese Academy of Sciences (CAS) member, USTC pioneered the Micius satellite in 2016—the world's first quantum science satellite—achieving intercontinental QKD over 1,200 kilometers.
The university's Hefei National Laboratory and Shanghai Research Center for Quantum Science have attracted global talent, with Pan's team producing over 300 high-impact papers. This ecosystem has trained thousands of students, many now leading quantum efforts worldwide, underscoring USTC's role in China's national quantum strategy.
The Trapped-Ion Quantum Memory Innovation
At the heart of the breakthrough is a long-lived trapped-ion quantum memory. Ions, such as ytterbium or calcium, are confined in Paul traps using radiofrequency fields. Quantum states are encoded in hyperfine levels, achieving coherence times exceeding 1 second—far surpassing the millisecond-scale needed for repeater operations.
The team developed an efficient ion-photon interface, converting ion states to telecom-wavelength photons (1550 nm) with >90% efficiency, minimizing loss during distribution. A high-visibility single-photon entanglement protocol ensures fidelity >95%, enabling swapping without significant degradation.
Experimental Setup and Protocol
The experiment involved two remote nodes, each with trapped-ion memories connected by 10 km fiber. Photons from one node are sent to the other, heralding entanglement upon coincident detection. The entanglement lifetime exceeded the ~100 ms generation cycle, allowing purification and swapping simulations.
Complementing this, a Science paper from the same team demonstrated device-independent QKD (DI-QKD) over 100 km using single atoms, generating 1.2 million Bell pairs over 624 hours at 11 km, yielding 0.112 bits per event secure key rate. This proves security without trusting devices, a gold standard for quantum crypto.
Key Results and Performance Metrics
Results show entanglement fidelity >90% post-loss compensation, with decoherence time > establishment time by factor of 10. DI-QKD achieved positive key rates up to 101 km asymptotically, 3,000 times beyond prior fiber records.
- Memory coherence time: >1 second
- Ion-photon efficiency: >90%
- Entanglement visibility: >95%
- DI-QKD distance: 100 km feasible
- Key rate at 11 km: 0.112 bps/event
These metrics surpass the repeaterless bound (PLOB), confirming repeater viability.
Implications for Secure Quantum Communication
This USTC quantum communication breakthrough enables global-scale QKD networks without trusted relays, critical for banking, government, and military. In China, it bolsters the Beijing-Shanghai quantum backbone (2,000 km operational since 2017), potentially extending to satellite links for intercontinental security.Read the full Nature paper
DI-QKD ensures security even against device-side attacks, vital amid rising cyber threats.
Towards the Quantum Internet
Quantum repeaters are foundational for the quantum internet, interconnecting quantum computers for distributed computing and sensing. USTC's module scales to multi-node networks, with purification extending range to thousands of km. Future iterations could integrate with photonic chips for hybrid systems.
Pan Jianwei and USTC's Research Ecosystem
Jian-Wei Pan, USTC's quantum pioneer, leads a team blending PhDs, postdocs, and undergrads. His groups have secured billions in funding from NSFC and MOST, fostering interdisciplinary training in physics, engineering, and informatics. USTC's quantum PhD program graduates ~100 annually, many securing faculty positions globally.
Boosting Higher Education and Talent in China
USTC exemplifies China's quantum talent pipeline, with government initiatives like the Quantum Information Major Project investing >$15B (2021-2025). Universities like Tsinghua and PKU collaborate, but USTC leads with 40% of high-impact quantum papers. This attracts international students, enhancing China's higher ed global standing.
Programs emphasize hands-on labs, producing innovators for QuantumCTek and Origin Quantum startups.
Career Opportunities in Quantum at Chinese Universities
Quantum research booms in China, with USTC hiring postdocs (¥400k+/year) and faculty (tenure-track). Roles span trapped-ion engineering, photonics, and theory. China's 14th Five-Year Plan prioritizes quantum, offering scholarships for PhDs. Explore positions via China research jobs.
Future Outlook and Global Collaboration
USTC plans 100-km repeater demos by 2027, integrating with satellites for quantum internet prototype. Collaborations with EU Quantum Flagship could standardize protocols. For Chinese higher ed, this cements leadership, inspiring STEM enrollment surges (quantum majors up 300% since 2020).
Stakeholders, from policymakers to students, see actionable paths: invest in ion-trap fabs, expand curricula, foster startups. USTC's advance not only secures data but elevates China's universities as quantum hubs.
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