Strontium optical lattice clock

Abstract

The strontium optical lattice clock has experienced a rapid development since the beginning of the 21st century. Its relative frequency uncertainty, on the order of 10-18, has surpassed that of the cesium fountain clock, the current primary standard for time and frequency. This supreme level of precision reflects one of the most advanced measurement capabilities of mankind. This article reviews the current progress of the strontium optical lattice clock, and describes its key components and techniques, including high-resolution spectroscopy, close-loop operation, evaluation of systematic shifts, and absolute frequency measurement. The applications and future outlook of the strontium clock are also summarized.