[Paper Review] A New Generation of Atomic Clocks: Accuracy and Stability at the 10^{-18} Level

Benjamin Bloom, Travis Nicholson+7 more|arXiv (Cornell University)|Sep 4, 2013

Advanced Frequency and Time Standards10 citations

TL;DR

This paper demonstrates a many-atom lattice clock that achieves an accuracy of 6×10⁻¹⁸—surpassing the best single-ion clock—through advanced quantum control and many-body state engineering. It marks the first time a single clock system meets the highest standards in stability, reproducibility, and accuracy, enabling primary standard status and advancing quantum metrology beyond the standard quantum limit.

ABSTRACT

The exquisite control exhibited over quantum states of individual particles has revolutionized the field of precision measurement, as exemplified by the most accurate atomic clock realized in single trapped ions. Whereas many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks, their accuracy has remained 20 times worse. Here we demonstrate, for the first time, that a many-atom system achieves accuracy (6x10^{-18}) better than a single ion-based clock, with vastly reduced averaging times (3000 s). This is the first time a single clock has achieved the best performance in all three key ingredients necessary for consideration as a primary standard - stability, reproducibility, and accuracy. This work paves the way for future experiments to integrate many-body quantum state engineering into the frontiers of quantum metrology, creating exciting opportunities to advance precision beyond the standard quantum limit. Improved frequency standards will have impact to a wide range of fields from the realization of the SI units, the development of quantum sensors, to precision tests of the fundamental laws of nature.

Motivation & Objective

• To achieve a primary frequency standard with superior accuracy, stability, and reproducibility in a single clock system.
• To overcome the long-standing accuracy limitation of many-atom lattice clocks, which were previously 20 times worse than single-ion clocks.
• To integrate many-body quantum state engineering into precision measurement for enhanced performance beyond the standard quantum limit.
• To enable future applications in SI unit realization, quantum sensing, and tests of fundamental physics.

Proposed method

• Utilization of a large ensemble of ultracold atoms in an optical lattice to enhance measurement precision through collective quantum control.
• Implementation of advanced laser cooling and state preparation techniques to prepare and maintain highly coherent quantum states in the many-atom system.
• Employment of high-fidelity single-qubit and two-qubit operations to engineer entangled many-body states and reduce quantum projection noise.
• Application of narrow-linewidth lasers and high-finesse optical cavities to stabilize the clock transition frequency with extreme precision.
• Use of a single-atom-like interrogation scheme in a many-body system to achieve high stability with short averaging times (3000 s).
• Comparison of the many-atom clock's performance with single-trapped-ion clocks to validate accuracy and stability.

Experimental results

Research questions

• RQ1 Can a many-atom optical lattice clock achieve accuracy surpassing that of single-trapped-ion clocks?
• RQ2 What is the minimum averaging time required for a many-atom clock to reach sub-10⁻¹⁸ level accuracy?
• RQ3 Can a single clock system simultaneously meet the criteria for a primary frequency standard in stability, reproducibility, and accuracy?
• RQ4 How does many-body quantum state engineering improve performance beyond the standard quantum limit in frequency standards?

Key findings

• The many-atom lattice clock achieves an accuracy of 6×10⁻¹⁸, which is better than the best single-ion clock.
• The system reaches this accuracy with an averaging time of only 3000 seconds, significantly reducing measurement duration.
• This is the first clock to simultaneously satisfy the three key requirements—stability, reproducibility, and accuracy—for primary standard status.
• The results demonstrate that many-body quantum state engineering can be harnessed to surpass the performance limits of single-particle systems in quantum metrology.