A dressed-state perturbation theory beyond the rotating wave approximation （RWA） is presented to investigate the interaction between a two-level electronic transition of polar molecules and a quantized cavity field....A dressed-state perturbation theory beyond the rotating wave approximation （RWA） is presented to investigate the interaction between a two-level electronic transition of polar molecules and a quantized cavity field. Analytical expressions can be explicitly derived for both the ground- and excited-state-energy spectrums and wave functions of the system, where the contribution of permanent dipole moments （PDM） and the counter-rotating wave term （CRT） can be shown separately. The validity of these explicit results is discussed by comparison with the direct numerical simulation. Compared to the CRT coupling, PDM results in the coupling of more dressed states and the energy shift is proportional to the square of the normalized permanent dipole difference, and a greater Bloch-Siegert shift can be produced in the giant dipole molecule cavity QED. In addition, our method can also be extended to the solution of the two-level atom Rabi model Hamiltonian beyond the RWA.展开更多
We develop a permanent-magnet Zeeman slower with adjustable magnets along the longitudinal and radial directions.Produced by four arrays of cylindrical magnets, the longitudinal magnetic field in the slower is tunable...We develop a permanent-magnet Zeeman slower with adjustable magnets along the longitudinal and radial directions.Produced by four arrays of cylindrical magnets, the longitudinal magnetic field in the slower is tunable if relevant parameters vary, for example, laser detuning or intensity. The proposed Zeeman slower can be reconfigured for Sr atoms. Additionally,we demonstrate that the residual magnetic field produced by the permanent magnets in the magneto-optical trap region can be as small as 0.5 Gs.展开更多
Permanent dipole moments induced high-order harmonic generation(HHG)signals offer a potential approach to producing elliptically or even circularly polarized X-ray attosecond sources.Previous studies on this topic hav...Permanent dipole moments induced high-order harmonic generation(HHG)signals offer a potential approach to producing elliptically or even circularly polarized X-ray attosecond sources.Previous studies on this topic have mainly focused on diatomic molecules such as CO and HeH.Based on this scheme,significant HHG signals in the direction perpendicular to the molecular axis can be observed in both the high-energy and low-energy regions.However,we found that the high-order harmonics induced by the permanent dipole moments of polyatomic complex molecules involve more intricate physical processes.Using time-dependent density functional theory,we simulated the dynamics of HHG from NH2COOH and NH2COSH interacting with linearly polarized lasers.We found that the harmonic signals in the direction perpendicular to the N-C bond were significantly enhanced in the high-energy photon region.Our analysis indicates that this is due to the complex molecular configuration of NH_(2)COOH and NH_(2)COSH:while the NH_(2) group has C_(2v) symmetry,both COOH and COSH groups lack this symmetry.This structural characteristic results in permanent dipole moments being felt only when electrons return to either COSH or COOH groups,but not to NH_(2) group.Additionally,our results reveal a multi-plateau structure in HHG signal along laser polarization direction,a phenomenon arising from multi-electron and multiorbital effects during interaction between complex molecule and strong laser field.展开更多
The potential energy curves of the molecule CdS have been calculated for 245 internuclear distances in the range 2.15 A 〈 r ≤6.471 A for 17 states in the representation 2S＋lA（±）via CASSCF method. Multirefere...The potential energy curves of the molecule CdS have been calculated for 245 internuclear distances in the range 2.15 A 〈 r ≤6.471 A for 17 states in the representation 2S＋lA（±）via CASSCF method. Multireference CI calculations （single and double excitations with Davidson corrections） were performed by using Gaussian basis sets for the two considered atoms. The potential energy curves, the harmonic frequency ωe, the internuclear distance re, the rotational constant Be, the electronic energy with respect to the ground state Te and the static dipole moment have been calculated. The comparison of these values to the available data in the literature shows a good agreement. To the best of our knowledge, eleven electronic states have been investigated here for the first time.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB01010200)the Hundred Talents Program of the Chinese Academy of Sciences(Grant No.Y321311401)+2 种基金the National Natural Science Foundation of China(Grant Nos.61475139,11347147,and11247014)the National Basics Research Program of China(Grant No.2013CB329501)the Zhejiang Provincial Natural Science Foundation(Grant No.LQ13A040006)
文摘A dressed-state perturbation theory beyond the rotating wave approximation （RWA） is presented to investigate the interaction between a two-level electronic transition of polar molecules and a quantized cavity field. Analytical expressions can be explicitly derived for both the ground- and excited-state-energy spectrums and wave functions of the system, where the contribution of permanent dipole moments （PDM） and the counter-rotating wave term （CRT） can be shown separately. The validity of these explicit results is discussed by comparison with the direct numerical simulation. Compared to the CRT coupling, PDM results in the coupling of more dressed states and the energy shift is proportional to the square of the normalized permanent dipole difference, and a greater Bloch-Siegert shift can be produced in the giant dipole molecule cavity QED. In addition, our method can also be extended to the solution of the two-level atom Rabi model Hamiltonian beyond the RWA.
基金Project supported by the National Key Basic Research and Development Program of China(Grant Nos.2012CB821302 and 2016YFA0302103)the National Natural Science Foundation of China(Grant No.11134003)+1 种基金the National High Technology Research and Development Program of China(Grant No.2014AA123401)the Shanghai Excellent Academic Leaders Program of China(Grant No.12XD1402400)
文摘We develop a permanent-magnet Zeeman slower with adjustable magnets along the longitudinal and radial directions.Produced by four arrays of cylindrical magnets, the longitudinal magnetic field in the slower is tunable if relevant parameters vary, for example, laser detuning or intensity. The proposed Zeeman slower can be reconfigured for Sr atoms. Additionally,we demonstrate that the residual magnetic field produced by the permanent magnets in the magneto-optical trap region can be as small as 0.5 Gs.
基金supported by the Fundamental Research Funds for the Central Universities(Grant Nos.GK202207012 and QCYRCXM-2022-241).
文摘Permanent dipole moments induced high-order harmonic generation(HHG)signals offer a potential approach to producing elliptically or even circularly polarized X-ray attosecond sources.Previous studies on this topic have mainly focused on diatomic molecules such as CO and HeH.Based on this scheme,significant HHG signals in the direction perpendicular to the molecular axis can be observed in both the high-energy and low-energy regions.However,we found that the high-order harmonics induced by the permanent dipole moments of polyatomic complex molecules involve more intricate physical processes.Using time-dependent density functional theory,we simulated the dynamics of HHG from NH2COOH and NH2COSH interacting with linearly polarized lasers.We found that the harmonic signals in the direction perpendicular to the N-C bond were significantly enhanced in the high-energy photon region.Our analysis indicates that this is due to the complex molecular configuration of NH_(2)COOH and NH_(2)COSH:while the NH_(2) group has C_(2v) symmetry,both COOH and COSH groups lack this symmetry.This structural characteristic results in permanent dipole moments being felt only when electrons return to either COSH or COOH groups,but not to NH_(2) group.Additionally,our results reveal a multi-plateau structure in HHG signal along laser polarization direction,a phenomenon arising from multi-electron and multiorbital effects during interaction between complex molecule and strong laser field.
文摘The potential energy curves of the molecule CdS have been calculated for 245 internuclear distances in the range 2.15 A 〈 r ≤6.471 A for 17 states in the representation 2S＋lA（±）via CASSCF method. Multireference CI calculations （single and double excitations with Davidson corrections） were performed by using Gaussian basis sets for the two considered atoms. The potential energy curves, the harmonic frequency ωe, the internuclear distance re, the rotational constant Be, the electronic energy with respect to the ground state Te and the static dipole moment have been calculated. The comparison of these values to the available data in the literature shows a good agreement. To the best of our knowledge, eleven electronic states have been investigated here for the first time.
