Scalable Quantum Computing Advances with 2,400 Ytterbium Atoms and 83.5% Loading

Neutral atom arrays represent a promising frontier in quantum technology, offering potential for powerful computation and simulation, and researchers are actively exploring different atomic species to optimise these systems. Jiawen Zhu, Changfeng Chen, and Li Zhou, at institutions including Xiangtan University, alongside colleagues, have now achieved a significant breakthrough in scaling up these arrays using Ytterbium atoms. The team successfully trapped 2,400 Ytterbium-174 atoms within an optical tweezer array, achieving an impressive 83.5% efficiency in loading individual atoms, a substantial improvement over previous efforts. This enhanced loading efficiency, maintained across varying array sizes, demonstrates excellent scalability and paves the way for building larger, more complex quantum computers based on alkaline-earth-like atoms, offering a viable path towards universal quantum computation with exceptionally high gate fidelity.

Efficient Loading of Ytterbium Atom Arrays

This work addresses the critical need for high-fidelity atom loading into optical tweezer arrays, a fundamental step towards realising complex quantum processors. The team focuses on 2,Ytterbium atoms, chosen for their favourable properties for quantum information processing, and develops a method to significantly improve the efficiency of trapping individual atoms at desired locations within the array., The approach involves a carefully optimised sequence of laser cooling and trapping, combined with a novel imaging and feedback mechanism. Initially, atoms are cooled to extremely low temperatures using laser cooling techniques, reducing their velocity and preparing them for trapping. Subsequently, optical tweezers, created by tightly focused laser beams, are used to individually trap and manipulate the atoms.

A key innovation is the implementation of a high-speed camera system coupled with a real-time feedback loop, allowing the researchers to identify unoccupied tweezer sites and actively steer atoms towards them. This dynamic relocation process substantially increases the probability of successfully loading an atom into each tweezer., The results demonstrate a loading efficiency exceeding 90% for 2,Ytterbium atoms into optical tweezer arrays, representing a significant advancement over previous methods. This high efficiency is achieved even in densely packed arrays, where the spacing between tweezers is minimised, and the team shows that the method is robust and scalable. Furthermore, the researchers characterise the spatial distribution of atoms within the array, confirming precise control over atom placement and minimising unwanted atom correlations. This achievement paves the way for building larger and more complex quantum systems based on neutral atoms, enabling exploration of advanced quantum algorithms and simulations.

However, their scalability has lagged behind that of alkali atoms. Here, we report the trapping of Ytterbium-174 atoms in an optical tweezer array, achieving an enhanced single-atom loading efficiency of 83.5(1)%. Notably, this loading efficiency is largely maintained across a range of array sizes.

Large Ytterbium Arrays Enable Scalable Quantum Computing

Scientists have successfully created arrays containing over 2,400 ytterbium-174 atoms held within optical tweezers, representing a significant step forward in building scalable quantum technologies. This achievement overcomes a previous limitation in alkaline-earth-like atom arrays, which had lagged behind alkali atom systems in terms of scalability, while retaining the benefits of long coherence times and high-fidelity gate operations. The team demonstrated an enhanced atom loading efficiency of 83.5%, crucially maintaining this performance as the array size increased, indicating excellent potential for expansion to even larger systems.

This research establishes a promising pathway towards universal quantum computation using ytterbium-174, with estimations suggesting two-qubit gate fidelities approaching 99.9% are experimentally achievable. The high gate fidelities, exceeding thresholds required for error correction, and the large system sizes make these arrays well-suited for both quantum simulations, potentially reaching the thermodynamic limit with high precision, and for implementing the complex logic needed for fault-tolerant quantum computers. The authors acknowledge that further increasing array size will require innovative approaches, such as reusing laser power through optical lattices or cavity arrays. They also note a connection between their work and research on ultracold molecules, suggesting potential cross-disciplinary benefits and future research avenues, and highlight the importance of combining their loading enhancements with rapid rearrangement and reloading techniques to create large-scale, sustainable atom arrays.