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Coherent Optical Clock Down-Conversion for Microwave Frequencies with 10-18 Instability



Takuma Nakamura, Josue Davila-Rodriguez, Holly Leopardi, Jeffrey Sherman, Tara Fortier, Xiaojun Xie, Joe C. Campbell, Will McGrew, Xiaogang Zhang, Youssef Hassan, Daniele Nicolodi, Kyle Beloy, Andrew Ludlow, Scott Diddams, Franklyn Quinlan


Optical atomic clocks are poised to redefine the SI second, thanks to stability and accuracy more than one hundred times better than the current microwave atomic clock standard. However, the best optical clocks have not seen their performance transferred to the electronic domain, where radar, navigation, communications, and fundamental research rely on less stable microwave sources. By comparing two independent optical-to-electronic signal generators, we demonstrate a 10 GHz microwave signal with phase that exactly tracks that of the optical clock phase from which it is derived, yielding an absolute fractional frequency stability of 1×10-18 in the electronic domain. Such faithful reproduction of the optical clock phase expands the opportunities for optical clocks in both technologically and scientifically for time- dissemination, navigation, and long-baseline interferometric imaging.
Science Magazine


low noise microwave generation, optical atomic clock, optical frequency comb, optical frequency division


Nakamura, T. , Davila-Rodriguez, J. , Leopardi, H. , Sherman, J. , Fortier, T. , Xie, X. , Campbell, J. , McGrew, W. , Zhang, X. , Hassan, Y. , Nicolodi, D. , Beloy, K. , Ludlow, A. , Diddams, S. and Quinlan, F. (2020), Coherent Optical Clock Down-Conversion for Microwave Frequencies with 10-18 Instability, Science Magazine, [online], (Accessed April 19, 2024)
Created May 22, 2020, Updated March 25, 2024