Description
Speaker:
Dr Yong Wan
University of Science and Technology of China
Abstract:
Trapped-ion systems have achieved exceptional performance in local quantum control, with long coherence times and high-fidelity operations routinely demonstrated in single-node processors. Extending these capabilities to longdistance networking, however, introduces a fundamental challenge: exponential photon loss in optical fibre suppresses entanglement generation rates, often causing remote entanglement to decay before subsequent links can be established.
Restoring balance between entanglement generation and memory coherence in the telecom-loss regime is a central requirement for scalable quantum repeaters.
Here, we demonstrate memory–memory entanglement between two trapped-ion
nodes connected by telecom fibre, with the entangled-state coherence time exceeding the average entanglement generation time under realistic link delay [1]. This operational regime is achieved through the co-optimization of long-lived ion memories, phase-stabilized single-photon interference, and low-noise quantum frequency conversion to the telecom band. Entering this rate–coherence-balanced regime enables reusable entanglement, in which sequential entanglement generation and storage become viable within a single link.
As a proof-of-principle application, we implement device-independent quantum key distribution over spooled fibre links. More broadly, crossing this threshold shifts the focus from demonstrating a single high-performance connection to systematically upgrading node capabilities and expanding network topology. In trapped-ion platforms, mixed-species memories and cavity-enhanced photon interfaces provide scalable routes toward higher link eiciency, while multi-ion nodes enable entanglement swapping and purification across extended chains. Together, these elements outline a practical pathway from two-node demonstrations to modular trapped-ion quantum networks.
[1] Liu et al., Nature 626, 263 (2026).