The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 ...The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.展开更多
An ultra-highly precise and long-term stable frequency transmission system over 120 km commercial fiber link has been proposed and experimentally demonstrated. This system is based on digital output compensation techn...An ultra-highly precise and long-term stable frequency transmission system over 120 km commercial fiber link has been proposed and experimentally demonstrated. This system is based on digital output compensation technique to suppress phase fluctuations during the frequency transmission process. A mode-locked erbium-doped fiber laser driven by a hydrogen maser serves as an optical transmitter. Moreover, a dense wavelength division multiplexing system is able to separate forward and backward signals with reflection effect excluded. The ultimate fractional frequency instabilities for the long-distance frequency distributed system are up to 3.14×10^(-15) at 1 s and 2.96×10^(-19) at 10 000 s, respectively.展开更多
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
The dissipative Kerr soliton(DKS)frequency comb exhibits broad and narrow-linewidth frequency modes,which make it suitable for quantum communication.However,a scalable quantum network based on multiple independent com...The dissipative Kerr soliton(DKS)frequency comb exhibits broad and narrow-linewidth frequency modes,which make it suitable for quantum communication.However,a scalable quantum network based on multiple independent combs is still a challenge due to fabrication-induced frequency mismatches.This limitation becomes critical in measurement-deviceindependent quantum key distribution,which requires high visibility of Hong–Ou–Mandel interference between multiple frequency channels.Here,we experimentally demonstrate two independent DKS combs with 10 spectrally aligned lines without any frequency locking system.The visibility for individual comb-line pairs reaches up to 46.72%±0.63%via precision frequency translation,establishing a foundation for deploying DKS combs in multi-user quantum networks.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61405002,91336103,10934010,61535001 and 61078026
文摘The absolute frequency of 87Rb 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition at 778nm is measured in an accuracy of 44kHz. A home-made erbium-doped fiber laser frequency comb with frequency stability of 5.0 × 10-13@1 s is employed for the light source. By using a periodically poled lithium niobate, the femtosecond pulse operating in 1556 nm is frequency-doubled to 778 nm to obtain the direct two-photon transition spectroscopy of thermal rubidium vapor. Through sweeping the carrier envelope offset frequency （fceo）, the 5S1/2 （F=2）→5D5/2 （F＂ = 4） two-photon transition line is clearly resolved and its absolute frequency is determined via the peak-finding of the fitting curve. After the frequency correction, the measured result agrees well with the previous experiment on this transition. The entire potential candidate of optical frequency standard for system configuration is compact and robust, providing a telecommunication applications.
基金supported by the National Natural Science Foundation of China(Nos.61571244 and 61501262)the Science and Technology Project of Tianjin(No.16YFZCSF00540)the Natural Science Foundation of Tianjin(No.15JCYBJC51600)
文摘An ultra-highly precise and long-term stable frequency transmission system over 120 km commercial fiber link has been proposed and experimentally demonstrated. This system is based on digital output compensation technique to suppress phase fluctuations during the frequency transmission process. A mode-locked erbium-doped fiber laser driven by a hydrogen maser serves as an optical transmitter. Moreover, a dense wavelength division multiplexing system is able to separate forward and backward signals with reflection effect excluded. The ultimate fractional frequency instabilities for the long-distance frequency distributed system are up to 3.14×10^(-15) at 1 s and 2.96×10^(-19) at 10 000 s, respectively.
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.
基金supported by the National Key Research and Development Program of China(No.2022YFE0137000)the Natural Science Foundation of Jiangsu Province(Nos.BK20240006 and BK20233001)+2 种基金the Leading-Edge Technology Program of Jiangsu Natural Science Foundation(No.BK20192001)the Fundamental Research Funds for the Central Universities,and the Innovation Program for Quantum Science and Technology(Nos.2021ZD0300700 and 2021ZD0301500)the Fundamental Research Funds for the Central Universities(No.2024300324)。
文摘The dissipative Kerr soliton(DKS)frequency comb exhibits broad and narrow-linewidth frequency modes,which make it suitable for quantum communication.However,a scalable quantum network based on multiple independent combs is still a challenge due to fabrication-induced frequency mismatches.This limitation becomes critical in measurement-deviceindependent quantum key distribution,which requires high visibility of Hong–Ou–Mandel interference between multiple frequency channels.Here,we experimentally demonstrate two independent DKS combs with 10 spectrally aligned lines without any frequency locking system.The visibility for individual comb-line pairs reaches up to 46.72%±0.63%via precision frequency translation,establishing a foundation for deploying DKS combs in multi-user quantum networks.
