The photo-dissociation dynamics of LiF is investigated with newly constructed accurate ab initio potential energy curves （PECs） using the time-dependent quantum wave packet method. The oscillations and decay of the ...The photo-dissociation dynamics of LiF is investigated with newly constructed accurate ab initio potential energy curves （PECs） using the time-dependent quantum wave packet method. The oscillations and decay of the wave packet on the adiabats as a function of time are given, which can be compared with the femtosecond transition-state （FTS） spectroscopy. The photo-absorption spectra and the kinetic-energy distribution of the dissociation fragments, which can exhibit the vibration-level structure and the dispersion of the wave packet, respectively, are also obtained. The investigation shows a blue shift of the band center for the photo-absorption spectrum and multiple peaks in the kinetic-energy spectrum with increasing laser intensity, which can be attributed to external field effects. By analyzing the oscillations of the wave packet evolving on the upper adiabat, an approximate inversion scheme is devised to roughly deduce its shape.展开更多
We study theoretically the effect of weak external magnetic fields on persistent spin helix states in semiconductor two-dimensional electron gases with both Rashba and linear-in-momentum Dresselhaus spin-orbit couplin...We study theoretically the effect of weak external magnetic fields on persistent spin helix states in semiconductor two-dimensional electron gases with both Rashba and linear-in-momentum Dresselhaus spin-orbit coupling.We show that in the presence of weak external magnetic fields, some basic properties of a persistent spin helix state,including the dispersion relation between the decay time and the magnitude of the wavevector, the maximum decay time and the value of the characteristic magnitude of the wavevector at which the maximum decay time occurs, will all depend sensitively on the directions of applied external magnetic fields.展开更多
Recent advances in atomic optical clocks based on electronic transitions have achieved frequency uncertainties at the10^(-19)level,enabling wide applications in testing variations of physical constants,exploring dark ...Recent advances in atomic optical clocks based on electronic transitions have achieved frequency uncertainties at the10^(-19)level,enabling wide applications in testing variations of physical constants,exploring dark matter signatures,and enhancing precision metrology for position,navigation,and timing systems.To pursue higher-precision optical clocks,the development of nuclear optical clocks has emerged,with the^(229)Th system distinguished by its unique low-lying isomeric state at~8.4 eV and a natural linewidth of approximately 100μHz,promising uncertainties below 10^(-19).The intrinsic insensitivity of nuclear transitions to external perturbations and their subatomic-scale spatial confinement provide significant advantages over electronic transitions in mitigating environmental shifts.Recent experimental breakthroughs include the excitation of the nuclear clock transition in solid-state^(229)Th-doped crystals with spectral resolution at the k Hz level.However,critical challenges persist,particularly in implementing effective laser excitation schemes(e.g.,via the electronic bridge mechanism)and closed-loop quantum control in trapped ion systems.Addressing these requires comprehensive understanding of complex many-body interactions in^(229)Th,encompassing electronic structure,nuclear deformation,hyperfine and field shift,and solid-state environmental coupling.This review synthesizes recent advancements in(i)the characterization of nuclear and atomic structures of the^(229)Th nuclear clock,and(ii)precise evaluation and mitigation of external perturbations affecting the clock transitions.The analysis provides a solid theoretical and experimental foundation for optimizing^(229)Th-based nuclear clock performance.展开更多
基金the International Cooperation Program for Excellent Lectures of 2008 by Shandong Provincial Education Department,Chinathe National Natural Science Foundation of China(Grant No.11074151)Fundao para a Ciência e a Tecnologia,Portugal
文摘The photo-dissociation dynamics of LiF is investigated with newly constructed accurate ab initio potential energy curves （PECs） using the time-dependent quantum wave packet method. The oscillations and decay of the wave packet on the adiabats as a function of time are given, which can be compared with the femtosecond transition-state （FTS） spectroscopy. The photo-absorption spectra and the kinetic-energy distribution of the dissociation fragments, which can exhibit the vibration-level structure and the dispersion of the wave packet, respectively, are also obtained. The investigation shows a blue shift of the band center for the photo-absorption spectrum and multiple peaks in the kinetic-energy spectrum with increasing laser intensity, which can be attributed to external field effects. By analyzing the oscillations of the wave packet evolving on the upper adiabat, an approximate inversion scheme is devised to roughly deduce its shape.
基金Supported by the National Natural Science Foundation of China under Grant No.10874049
文摘We study theoretically the effect of weak external magnetic fields on persistent spin helix states in semiconductor two-dimensional electron gases with both Rashba and linear-in-momentum Dresselhaus spin-orbit coupling.We show that in the presence of weak external magnetic fields, some basic properties of a persistent spin helix state,including the dispersion relation between the decay time and the magnitude of the wavevector, the maximum decay time and the value of the characteristic magnitude of the wavevector at which the maximum decay time occurs, will all depend sensitively on the directions of applied external magnetic fields.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB0920100 and XDB0920101)the National Natural Science Foundation of China(Grant Nos.12174402,12393821,12274417)the Chinese Academy of Sciences Project for Young Scientists in Basic Research(Grant No.YSBR-055)。
文摘Recent advances in atomic optical clocks based on electronic transitions have achieved frequency uncertainties at the10^(-19)level,enabling wide applications in testing variations of physical constants,exploring dark matter signatures,and enhancing precision metrology for position,navigation,and timing systems.To pursue higher-precision optical clocks,the development of nuclear optical clocks has emerged,with the^(229)Th system distinguished by its unique low-lying isomeric state at~8.4 eV and a natural linewidth of approximately 100μHz,promising uncertainties below 10^(-19).The intrinsic insensitivity of nuclear transitions to external perturbations and their subatomic-scale spatial confinement provide significant advantages over electronic transitions in mitigating environmental shifts.Recent experimental breakthroughs include the excitation of the nuclear clock transition in solid-state^(229)Th-doped crystals with spectral resolution at the k Hz level.However,critical challenges persist,particularly in implementing effective laser excitation schemes(e.g.,via the electronic bridge mechanism)and closed-loop quantum control in trapped ion systems.Addressing these requires comprehensive understanding of complex many-body interactions in^(229)Th,encompassing electronic structure,nuclear deformation,hyperfine and field shift,and solid-state environmental coupling.This review synthesizes recent advancements in(i)the characterization of nuclear and atomic structures of the^(229)Th nuclear clock,and(ii)precise evaluation and mitigation of external perturbations affecting the clock transitions.The analysis provides a solid theoretical and experimental foundation for optimizing^(229)Th-based nuclear clock performance.
