通过70 dB自由空间信道的时频传递：面向星地时间传播
Time-Frequency Transfer through a 70 dB Free Space Channel: Towards Satellite-Ground Time Dissemination
摘要：
时间和频率传输是计量领域的核心。与目前的微波传播如GPS相比，光域传播可以提供一个数量级以上的精度，这使得许多应用成为可能，如秒的重新定义，广义相对论和基础量子物理的测试，精密导航和量子通信。虽然光频率传输已经在数千公里的光纤线路上得到了验证，但洲际时间比对和同步仍然需要卫星自由空间光时间和频率传输。在几十公里的地面上进行了多项开创性的自由空间光时频实验。然而，目前还没有详细的分析或地面测试来证明基于卫星的光时频传递的可行性。在此，我们分析了该系统的可能性，然后提供了第一步的地面测试与高通道损耗。在16 km的自由空间信道上，利用8,000 s的时间实现了$10^{-18}$量级的光频率传输，传输损耗高达70 dB，与中地球轨道（MEO）和地球静止轨道（GEO）的星地链路损耗相当.
英文摘要：
Time and frequency transfer lies at the heart of the field of metrology. Compared to current microwave dissemination such as GPS, optical domain dissemination can provide more than one order of magnitude in terms of higher accuracy, which allows for many applications such as the redefinition of the second, tests of general relativity and fundamental quantum physics, precision navigation and quantum communication. Although optical frequency transfer has been demonstrated over thousand kilometers fiber lines, intercontinental time comparison and synchronization still requires satellite free space optical time and frequency transfer. Quite a few pioneering free space optical time and frequency experiments have been implemented at the distance of tens kilometers at ground level. However, there exists no detailed analysis or ground test to prove the feasibility of satellite-based optical time-frequency transfer. Here, we analyze the possibility of this system and then provide the first-step ground test with high channel loss. We demonstrate the optical frequency transfer with an instability of $10^{-18}$ level in 8,000 seconds across a 16-km free space channel with a loss of up to 70~dB, which is comparable with the loss of a satellite-ground link at medium earth orbit (MEO) and geostationary earth orbit (GEO).
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
