2009/01/19 by S. Weyers, B. Lipphardt, H. Schnatz · 84 citations
Computer Science · Physics and Astronomy · #Advanced Frequency and Time Standards #Fountain #Geography #Laser #Limit (mathematics) #Maser #Mechanical and Optical Resonators #Microwave #Optics #Optoelectronics #Phase (matter) #Physics #Quantum #Quantum Information and Cryptography #Quantum mechanics #physics.atom-ph
paper · pdf · doi:10.1103/physreva.79.031803
published in Physical Review A 79(3) (American Physical Society) · 4 pages, 4 figures
arxiv created 2009/01/19 · openalex publication_date 2009/03/11 · openalex created_date 2016/06/24 · arxiv updated 2018/10/22 · openalex updated_date 2026/08/05
A cesium fountain clock is operated utilizing a microwave oscillator that derives its frequency stability from a stable laser by means of a fiber-laser femtosecond frequency comb. This oscillator is based on the technology developed for optical clocks and replaces the quartz-based microwave oscillator commonly used in fountain clocks. As a result, a significant decrease in the frequency instability of the fountain clock is obtained, reaching 7.4\ifmmode×\else\texttimes\fi10^\ensuremath-14[\ensuremathτ (s)]^\ensuremath-1/2. We could demonstrate that for a significant range of detected atom numbers the instability is limited by quantum projection noise only, and that for the current status of this fountain clock the microwave source poses no limit on the achievable frequency instability.