An optical lattice clock

• Published in: Nature Vol. 435; no. 7040; pp. 321 - 324
• Main Authors: Katori, Hidetoshi, Takamoto, Masao, Hong, Feng-Lei, Higashi, Ryoichi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 19.05.2005; Nature Publishing Group
• Subjects: Atomic and molecular physics; Atomic properties and interactions with photons; Atoms & subatomic particles; Exact sciences and technology; Global positioning systems; GPS; Measurements common to several branches of physics and astronomy; Metrology, measurements and laboratory procedures; Optical cooling of atoms; trapping; Photon interactions with atoms; Physics; Time; Time and frequency; Optical lattices; Ultracold atom; Strontium Atoms; Frequency measurement; Experimental study; Optical frequency; Atom trapping; Atomic clocks; Strontium 87
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature03541

The precision measurement of time and frequency is a prerequisite not only for fundamental science but also for technologies that support broadband communication networks and navigation with global positioning systems (GPS). The SI second is currently realized by the microwave transition of Cs atoms with a fractional uncertainty of 10-15 (ref. 1). Thanks to the optical frequency comb technique, which established a coherent link between optical and radio frequencies, optical clocks have attracted increasing interest as regards future atomic clocks with superior precision. To date, single trapped ions and ultracold neutral atoms in free fall have shown record high performance that is approaching that of the best Cs fountain clocks. Here we report a different approach, in which atoms trapped in an optical lattice serve as quantum references. The 'optical lattice clock' demonstrates a linewidth one order of magnitude narrower than that observed for neutral-atom optical clocks, and its stability is better than that of single-ion clocks. The transition frequency for the Sr lattice clock is 429,228,004,229,952(15) Hz, as determined by an optical frequency comb referenced to the SI second.