A transportable optical lattice clock with $7\times10^{-17}$ uncertainty (1609.06183v1)

Abstract: We present a transportable optical clock (TOC) with $^{87}$Sr. Its complete characterization against a stationary lattice clock resulted in a systematic uncertainty of ${7.4 \times 10^{-17}}$ which is currently limited by the statistics of the determination of the residual lattice light shift. The measurements confirm that the systematic uncertainty is reduceable to below the design goal of $1 \times 10^{-17}$. The instability of our TOC is $1.3 \times 10^{-15}/\sqrt{(\tau/s)}$. Both, the systematic uncertainty and the instability are to our best knowledge currently the best achieved with any type of transportable clock. For autonomous operation the TOC is installed in an air-conditioned car-trailer. It is suitable for chronometric leveling with sub-meter resolution as well as intercontinental cross-linking of optical clocks, which is essential for a redefiniton of the SI second. In addition, the TOC will be used for high precision experiments for fundamental science that are commonly tied to precise frequency measurements and it is a first step to space borne optical clocks

Overview of the Transportable Optical Lattice Clock with $7\times10^{-17}$ Uncertainty

The paper presents a detailed technical exposition of a transportable optical clock (TOC) utilizing $^{87}$Sr atoms, designed and characterized with an impressive systematic uncertainty of $7.4 \times 10^{-17}$. This uncertainty is chiefly limited by the residual lattice light shift statistics. The TOC achieves an instability measured at $1.3 \times 10^{-15}$, establishing these figures as benchmarks for transportable clocks presently. These metrics notably surpass previous transportable atomic clock standards, improving operational efficacy for diverse applications, including precise geodetic measurements and potential intercontinental network linking of optical clocks.

Features and Comparison

The paper elucidates the construction and performance of this TOC when juxtaposed with a stationary optical lattice clock. Its instability and systematic uncertainty are characterized, demonstrating its superior performance attributes which currently stand unmatched by existing transportable clocks. The TOC operates within an air-conditioned car-trailer, emphasizing its mobility and adaptability beyond laboratory settings, which is critical for geodesic applications such as chronometric leveling and timekeeping advancements that could redefine the SI second.

Implications and Further Applications

The implications of this research are multifaceted, predominantly affecting chronometric leveling by exploiting gravitational redshifts for measuring height differences with sub-meter precision. The clock's portability potentiates international clock comparisons and tests of fundamental physics, expanding the applicability of transportable optical clocks in satellite and space endeavors. The level of precision attained is instrumental for advancing measurement techniques and redefining time standards at a global scale.

Insights on Uncertainty and Instability

The clock's systematic uncertainty was primarily governed by lattice light shift statistics, with potential reductions anticipated following thorough characterization of the lattice laser system. Further noted is the blackbody radiation shift as a fundamental source of uncertainty, managed by strategic thermal regulation within the TOC's components. The architecture allows achieving instabilities across short measurement spans, contributing to enhanced operational calibration and reliability in field applications.

Future Prospects and Developments

Continuous innovations could improve TOC efficiency and reduce statistical uncertainty even further. Adaptations foreseen include upgrading the interrogation laser for enhanced frequency stability and optimized blackbody-related uncertainty management, which could be crucial for achieving sub-$10^{-17}$ uncertainty levels. The TOC is positioned for pivotal advancements in global timing networks and precision science explorations, setting a foundation for redefined atomic timekeeping standards and methodologies.

Overall, the research delineates a significant advancement in transportable optical clock technology, with substantial implications for geodesic applications, fundamental physics explorations, and international timekeeping collaborations. Its compact, robust configuration provides a blueprint for future developments in precision measurement instruments essential for a fluctuating scientific landscape.