The realization of ultra-stable lasers with 10^(-17)-level frequency stability has enabled a wide range of researches on precision metrology and fundamental science,where cryogenic single-crystalline cavities constitu...The realization of ultra-stable lasers with 10^(-17)-level frequency stability has enabled a wide range of researches on precision metrology and fundamental science,where cryogenic single-crystalline cavities constitute the heart of such ultra-stable lasers.For further improvements in stability,increasing the cavity length at few-kelvin temperatures provides a promising alternative to utilizing relatively short cavities with novel coating,but has yet to be demonstrated with state-of-the-art stability.Here we report on the realization of a relatively long ultra-stable silicon cavity with a length of 10 cm and sub-5-K operating temperatures.We devise a dynamical protocol of cool-quiet quench measurement that reveals the inherent 10^(-17)-level frequency instability of the silicon cavity despite the substantially larger frequency noise induced by the cryostat vibration.We further develop a method for suppressing the cryostat-vibration-induced frequency noise under continuous cooling,and observe an average frequency instability of 4.3(2)×10^(-17) for averaging times of 4 to 12 s.Using the measured noise power spectral density,we compute a median linewidth of 9.6(3)mHz for the silicon cavity laser at 1397 nm,which is supported by an empirically determined linewidth of 5.7(3)mHz based on direct optical beat measurements.These results establish a new record for optical cavities within a closed-cycle cryocooler at sub-5-K temperatures and provide a prototypical system for using long cryogenic cavities to enhance frequency stabilities to the low-10^(-17)orbetter level.展开更多
基金supported by the Chinese Academy of Sciences Strategic Priority Research Program(XDB35020100)the Hefei National Laboratory,and the Innovation Program for Quantum Science and Technology(2021zD0301903).
文摘The realization of ultra-stable lasers with 10^(-17)-level frequency stability has enabled a wide range of researches on precision metrology and fundamental science,where cryogenic single-crystalline cavities constitute the heart of such ultra-stable lasers.For further improvements in stability,increasing the cavity length at few-kelvin temperatures provides a promising alternative to utilizing relatively short cavities with novel coating,but has yet to be demonstrated with state-of-the-art stability.Here we report on the realization of a relatively long ultra-stable silicon cavity with a length of 10 cm and sub-5-K operating temperatures.We devise a dynamical protocol of cool-quiet quench measurement that reveals the inherent 10^(-17)-level frequency instability of the silicon cavity despite the substantially larger frequency noise induced by the cryostat vibration.We further develop a method for suppressing the cryostat-vibration-induced frequency noise under continuous cooling,and observe an average frequency instability of 4.3(2)×10^(-17) for averaging times of 4 to 12 s.Using the measured noise power spectral density,we compute a median linewidth of 9.6(3)mHz for the silicon cavity laser at 1397 nm,which is supported by an empirically determined linewidth of 5.7(3)mHz based on direct optical beat measurements.These results establish a new record for optical cavities within a closed-cycle cryocooler at sub-5-K temperatures and provide a prototypical system for using long cryogenic cavities to enhance frequency stabilities to the low-10^(-17)orbetter level.
