The thorium-229 nucleus possesses a uniquely low-energy nuclear transition(-8.4 eV,corresponding to a wavelength of-148 nm),which is the first confirmed nuclear excitation that can be coherently manipulated by narrow-...The thorium-229 nucleus possesses a uniquely low-energy nuclear transition(-8.4 eV,corresponding to a wavelength of-148 nm),which is the first confirmed nuclear excitation that can be coherently manipulated by narrow-linewidth lasers.Consequently,this transition has garnered widespread interest over the past decades.Owing to the small nuclear size and strong resistance to environmental perturbations,a thorium-based nuclear clock is theoretically capable of achieving an unprecedented fractional frequency uncertainty at the 10^(−20) level,offering great promise as a next-generation frequency standard.Among the key ingredients of such a thorium-based nuclear clock,a high-performance 148 nm excitation source is of critical importance.Since the feasibility of directly exciting the transition,as well as the overall clock performance,depends heavily on the availability and quality of such a source,the development of high-quality 148 nm laser sources represents a frontier for scientists worldwide.In this article,we provide a systematic overview of the current development of 148 nm laser sources.First,we briefly introduce the scientific motivation for high-precision spectroscopy of the thorium nuclear transition and the corresponding technical requirements for 148 nm laser sources.Then,we summarize four main types of existing 148 nm source generation schemes and their working principles,along with recent progress in nuclear transition measurements using such sources.Finally,we discuss potential future directions.展开更多
We report experimental and theoretical investigations of wavelength dependence of Rydberg state excitation(RSE)process of Ar subject to intense laser fields.By simultaneously measuring ionization and RSE yields of Ar ...We report experimental and theoretical investigations of wavelength dependence of Rydberg state excitation(RSE)process of Ar subject to intense laser fields.By simultaneously measuring ionization and RSE yields of Ar atoms subject to strong laser fields at a series of wavelengths,we obtain the wavelength scaling law of the ratio of Ar^(*)over Ar^(+)with respect to the laser intensity,and this result can be well reproduced by a nonadiabatic model,but not by the classical-trajectory Monte Carlo model.Our results indicate that the nonadiabatic corrections of the photoelectron tunneling exit and tunneling probability play a significant role at shorter wavelengths.Analysis shows that the wavelength dependence phenomenon is due to the interplay of the nonadiabatic effect,wave-packet diffusion and Coulomb focusing effect of the liberated electron.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0920000)the National Natural Science Foundation of China(Grant Nos.12121004 and U21A20435)+1 种基金the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-055)the Science and Technology Department of Hubei Province(Grant No.2025AFA004)。
文摘The thorium-229 nucleus possesses a uniquely low-energy nuclear transition(-8.4 eV,corresponding to a wavelength of-148 nm),which is the first confirmed nuclear excitation that can be coherently manipulated by narrow-linewidth lasers.Consequently,this transition has garnered widespread interest over the past decades.Owing to the small nuclear size and strong resistance to environmental perturbations,a thorium-based nuclear clock is theoretically capable of achieving an unprecedented fractional frequency uncertainty at the 10^(−20) level,offering great promise as a next-generation frequency standard.Among the key ingredients of such a thorium-based nuclear clock,a high-performance 148 nm excitation source is of critical importance.Since the feasibility of directly exciting the transition,as well as the overall clock performance,depends heavily on the availability and quality of such a source,the development of high-quality 148 nm laser sources represents a frontier for scientists worldwide.In this article,we provide a systematic overview of the current development of 148 nm laser sources.First,we briefly introduce the scientific motivation for high-precision spectroscopy of the thorium nuclear transition and the corresponding technical requirements for 148 nm laser sources.Then,we summarize four main types of existing 148 nm source generation schemes and their working principles,along with recent progress in nuclear transition measurements using such sources.Finally,we discuss potential future directions.
基金Supported by the National Key Research and Development Program of China(Grant No.2019YFA0307700)the National Natural Science Foundation of China(Grant Nos.12004391,12104465,12274420,and U21A20435)+5 种基金China Postdoctoral Science Foundation(Grant Nos.2019M662752,2020T1306822022M713219)CAS Project for Young Scientists in Basic Research(Grant No.YSBR-055)the Science and Technology Department of Hubei Province(Grant No.2020CFA029)Knowledge Innovation Program of Wuhan-Shuguang Project(Grant No.2022020801020140)K.C.Wong Education Foundation。
文摘We report experimental and theoretical investigations of wavelength dependence of Rydberg state excitation(RSE)process of Ar subject to intense laser fields.By simultaneously measuring ionization and RSE yields of Ar atoms subject to strong laser fields at a series of wavelengths,we obtain the wavelength scaling law of the ratio of Ar^(*)over Ar^(+)with respect to the laser intensity,and this result can be well reproduced by a nonadiabatic model,but not by the classical-trajectory Monte Carlo model.Our results indicate that the nonadiabatic corrections of the photoelectron tunneling exit and tunneling probability play a significant role at shorter wavelengths.Analysis shows that the wavelength dependence phenomenon is due to the interplay of the nonadiabatic effect,wave-packet diffusion and Coulomb focusing effect of the liberated electron.
