Max-Planck-Institut für Quantenoptik, Garching, Germany.
Science. 2012 Apr 27;336(6080):441-4. doi: 10.1126/science.1218442.
Optical clocks show unprecedented accuracy, surpassing that of previously available clock systems by more than one order of magnitude. Precise intercomparisons will enable a variety of experiments, including tests of fundamental quantum physics and cosmology and applications in geodesy and navigation. Well-established, satellite-based techniques for microwave dissemination are not adequate to compare optical clocks. Here, we present phase-stabilized distribution of an optical frequency over 920 kilometers of telecommunication fiber. We used two antiparallel fiber links to determine their fractional frequency instability (modified Allan deviation) to 5 × 10(-15) in a 1-second integration time, reaching 10(-18) in less than 1000 seconds. For long integration times τ, the deviation from the expected frequency value has been constrained to within 4 × 10(-19). The link may serve as part of a Europe-wide optical frequency dissemination network.
光学时钟显示出前所未有的精度，比以前可用的时钟系统高出一个数量级以上。精确的相互比较将能够进行各种实验，包括对基本量子物理学和宇宙学的测试以及在大地测量学和导航中的应用。基于卫星的微波传播的成熟技术不足以比较光学时钟。在这里，我们展示了通过 920 公里长的电信光纤对光频率的相位稳定分布。我们使用两个反平行光纤链路来确定它们的分数频率不稳定度（改进的 Allan 偏差），在 1 秒的积分时间内达到 5×10(-15)，在不到 1000 秒内达到 10(-18)。对于较长的积分时间 τ，从预期频率值的偏差已被限制在 4×10(-19)以内。该链路可用作全欧光频率传播网络的一部分。
