Record Milestones! Optical Tweezer Array Captures Over 6,000 Neutral Atoms, Quantum Computing Reaches New Highs

March 18, 2024 Researchers have successfully developed a large-scale optical tweezers array capable of capturing more than 6,100 neutral atoms at 12,000 sites while reaching new heights in several key performance metrics:

1) Coherence time of 12.6 seconds, setting a new record for hyperfine quantum bits in an optical tweezers array;

2) A record capture lifetime of nearly 23 minutes in a room-temperature device;

3) an imaging survival rate of 99.98952% and an imaging fidelity of over 99.99%.

These findings, along with other recent advances, show that general-purpose quantum computing with tens of thousands of atomic quantum bits is expected to be realized in the near future. In addition, these works pave the way for quantum simulation and quantum metrology experiments with inherent single-particle readout and localization capabilities on a similar scale.

In recent years, optical tweezers arrays have revolutionized the study of atomic and molecular physics, and have become the cornerstone of a variety of cutting-edge experiments in fields such as quantum computing, simulation, and metrology.

The success of this technology is based on its inherent simplicity of single-particle control and detection. Typical experiments capture tens to hundreds of atomic quantum bits. Recent studies have shown that neutral atoms have long coherence times (up to 40 seconds), and Atom Computing has even managed to realize systems of about a thousand atoms without explicitly defining quantum bits or demonstrating coherence control.

In December 2023, three leading researchers in the field, Markus Greiner (Harvard University), Vladan Vuletic (Massachusetts Institute of Technology), and Mikhail Lukin (Harvard University, who first proposed the use of neutral atoms as quantum bits in his 2020 paper), published a paper in the journal Nature.

They describe a complex quantum processor consisting of several different functional regions. Each quantum bit is kept as a separate item in memory and is used to form logical quantum bits in groups of 20 quantum bits each. The entanglement zone is used for parallel encoding of quantum bits and gate operations, while the readout zone is responsible for measuring the quantum bits. The paper notes that this technique and the results obtained could enable the system to scale up to 10,000 quantum bits. According to the Harvard Gazette, this is the first logic quantum processor and is essential for realizing scalable quantum devices.

However, scaling the system to thousands of atomic quantum bits with long coherence times, low loss, and high-fidelity imaging remains a huge challenge, and is critical to advances in the fields of quantum computing, simulation, and metrology, especially for quantum error correction applications.

Recently, Caltech scientists marked an important milestone when they experimentally succeeded in developing an optical tweezers array capable of capturing more than 6,100 neutral atoms at about 12,000 sites.

The team reports that the overfrequency quantum bits in the array achieved a coherence time of 12.6 seconds, setting a new record for such devices. In addition, they achieved a capture lifetime of nearly 23 minutes at room temperature, with an imaging survival rate of 99.98952% and an imaging fidelity of more than 99.99%.

These results are of particular interest because they show that quantum computing platforms have overcome a major hurdle that has limited their scalability in the past. The team notes that these advances at least suggest that general-purpose quantum computing using tens of thousands of atomic quantum bits is feasible in the near future.

In the paper, the researchers wrote, “Ultimately, our study shows that it is feasible to further extend the optical tweezers array platform to tens of thousands of captured atoms through existing technologies while being able to largely maintain high-fidelity control.”

Nonetheless, the research team recognizes that there is still much work ahead of them that needs to be done, and some areas that still need to be further explored and developed. For example, while this experiment demonstrated excellent scalability and performance metrics, it did not cover the rearrangement of atoms or the entanglement of atomic quantum bits, both of which are critical for practical computational tasks.

In optical tweezers arrays, dynamically rearranging atoms is essential for executing complex algorithms and implementing error correction.

Currently, a technical limitation faced by researchers is the limited number of spatial light modulator (SLM) pixels and the reduced diffraction efficiency at high incident laser powers, which limits the number of capture points. Future improvements may include the use of higher resolution spatial light modulators and techniques that utilize power and field of view more efficiently. Mitigation measures are also needed for optical aberrations caused by thermal heating of the objective lens, which is critical for further technology expansion.

Despite these challenges, the research team is optimistic about overcoming these obstacles by utilizing existing and future technological advances. They anticipate that high precision capture of tens of thousands of atoms will be realized in the future by further improving the fidelity of control.

[5]https://www.endreslab.com/

[6]https://mp.weixin.qq.com/s/mpzt57atud9SXW9kepTdoA