We present a scheme to control the generated ultrafast magnetic field in H_(3)^(2+)molecules using multi-frequency tricircular pulses composed of co-and counter-rotating bicircular pulses.Simulations show that the fie...We present a scheme to control the generated ultrafast magnetic field in H_(3)^(2+)molecules using multi-frequency tricircular pulses composed of co-and counter-rotating bicircular pulses.Simulations show that the field amplitude and the wavelength are two significant factors for magnetic field generation by tricircular pulses.Specifically,the strength of the magnetic field is linearly related to the field amplitude atλ_(0)=50 nm,while atλ_(0)=70 nm,the strength first increases and then decreases with the amplitude,this can be attributed to the resonance between the ground and excited states.Moreover,the phase and helicity of bicircular pulses are shown to have important effects on the magnetic field.The dependence of the magnetic field on the phase arises from the interference effect between multiple ionization pathways.These findings illustrate a guiding principle for controlling the magnetic field in molecular systems for future research in ultrafast magneto-optics.展开更多
We theoretically investigate the high-order harmonic generation(HHG) of helium atom driven by bichromatic counterrotating circularly polarized laser fields. By changing the intensity ratio of the two driving laser fie...We theoretically investigate the high-order harmonic generation(HHG) of helium atom driven by bichromatic counterrotating circularly polarized laser fields. By changing the intensity ratio of the two driving laser fields, the spectral chirality of the HHG can be controlled. As the intensity ratio increases, the spectral chirality will change from positive-to negativevalue around a large intensity ratio of the two driving fields when the total laser intensity keeps unchanged. However, the sign of the spectral chirality can be changed from positive to negative around a small intensity ratio of the two driving fields when the total laser intensity changes. At this time, we can effectively control the helicity of the harmonic spectrum and the polarization of the resulting attosecond pulses by adjusting the intensity ratio of the two driving laser fields. As the intensity ratio and the total intensity of the driving laser fields increase, the relative intensity of either the left-circularly or right-circularly polarized harmonic can be enhanced. The attosecond pulses can evolve from being elliptical to near linear correspondingly.展开更多
By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with di...By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with different orientation angles driven by elliptically polarized laser pulse with varying ellipticities. Our numerical results show that the MPMD is sensitive to the orientation angle and the laser ellipticity, which can be explained by the attosecond perturbation ionization theory and the exactly solvable photoionization model. When the ellipticity ε = 0, the final MPMD of x-oriented H^+_2 shows a distinct six-lobe pattern that is different from that with ε = 0.5 and ε = 1. The evolutions of electron wave packet(EWP)and MPMD with x-oriented H^+_2 are presented to interpret this distinct pattern.展开更多
Coherent electronic dynamics are of great significance in photo-induced processes and molecular magnetism.We theoretically investigate electronic dynamics of triatomic molecule H_(3)^(2+) by circularly polarized pulse...Coherent electronic dynamics are of great significance in photo-induced processes and molecular magnetism.We theoretically investigate electronic dynamics of triatomic molecule H_(3)^(2+) by circularly polarized pulses,including electron density distributions,induced electronic currents,and ultrafast magnetic field generation.By comparing the results of the coherent resonant excitation and direct ionization,we found that for the coherent resonant excitation,the electron is localized and the coherent electron wave packet moves periodically between three protons,which can be attributed to the coherent superposition of the ground A′state and excited E+state.Whereas,for the direct single-photon ionization,the induced electronic currents mainly come from the free electron in the continuum state.It is found that there are differences in the intensity,phase,and frequency of the induced current and the generated magnetic field.The scheme allows one to control the induced electronic current and the ultrafast magnetic field generation.展开更多
We present the photoelectron momentum distributions(PMDs) and the photoelectron angular distributions(PADs) of He+ ions, aligned H2+ molecules and N2 molecules by intense orthogonally polarized laser pulses. Simulatio...We present the photoelectron momentum distributions(PMDs) and the photoelectron angular distributions(PADs) of He+ ions, aligned H2+ molecules and N2 molecules by intense orthogonally polarized laser pulses. Simulations are performed by numerically solving the corresponding two-dimensional time-dependent Schr?dinger equations(TDSEs) within the single-electron approximation frame. Photoelectron momentum distributions and photoelectron angular distributions present different patterns with the time delays Td, illustrating the dependences of the PMDs and PADs on the time delays by orthogonally polarized laser pulses. The evolution of the electron wavepackets can be employed to describe the intensity of the PADs from the TDSE simulations for N2 molecules.展开更多
The ultrafast photoionization dynamics of N_(2) molecules by x-ray/XUV laser pulses is investigated.The molecular frame photoelectron momentum distributions(MF-PMDs) and the molecular frame photoelectron angular distr...The ultrafast photoionization dynamics of N_(2) molecules by x-ray/XUV laser pulses is investigated.The molecular frame photoelectron momentum distributions(MF-PMDs) and the molecular frame photoelectron angular distributions(MF-PADs) are obtained by numerically solving 2D time-dependent Schrodinger equations within the single-electron approximation(SEA) frame.The results show that the molecular photoionization diffraction appears in 5 nm laser fields.However,when the laser wavelength is 30 nm,the molecular photoionization diffraction disappears and the MF-PMDs show four-lobe pattern.The ultrafast photoionization model can be employed to describe the MF-PMDs and MF-PADs of N_(2) molecules.展开更多
In this paper we survey recent progress in symplectic algorithms for use in quantum systems in the following topics:Symplectic schemes for solving Hamiltonian systems;Classical trajectories of diatomic systems,model m...In this paper we survey recent progress in symplectic algorithms for use in quantum systems in the following topics:Symplectic schemes for solving Hamiltonian systems;Classical trajectories of diatomic systems,model molecule A2B,Hydrogen ion H+2 and elementary atmospheric reaction N(4S)+O2(X 3Σ−g)→NO(X 2Π)+O(3P)calculated by means of Runge-Kutta methods and symplectic methods;the classical dissociation of the HF molecule and classical dynamics of H+2 in an intense laser field;the symplectic form and symplectic-scheme shooting method for the time-independent Schr¨odinger equation;the computation of continuum eigenfunction of the Schr¨odinger equation;asymptotic boundary conditions for solving the time-dependent Schr¨odinger equation of an atom in an intense laser field;symplectic discretization based on asymptotic boundary condition and the numerical eigenfunction expansion;and applications in computing multi-photon ionization,above-threshold ionization,Rabbi oscillation and high-order harmonic generation of laser-atom interaction.展开更多
We theoretically investigate the vortex patterns in photoelectron momentum distributions of He^(+)driven by counter-rotating elliptically polarized,time delayed attosecond laser pulses by numerically solving the two-d...We theoretically investigate the vortex patterns in photoelectron momentum distributions of He^(+)driven by counter-rotating elliptically polarized,time delayed attosecond laser pulses by numerically solving the two-dimensional time-dependent Schrodinger equation.It is found that the number of vortex arms is extremely sensitive to the ellipticity and wavelength of counterrotating elliptically polarized laser pulses,which is illustrated by the attosecond perturbation ionization models.In addition,the effect of different time delays between two pulses on the interference patterns is also investigated and the corresponding physical mechanism is demonstrated.Since the wavelength,ellipticity and time delay have a significant effect on the vortex interference patterns,this may be a new method for laser field detection.展开更多
基金the National Natural Science Foundation of China(Grant No.12074146).
文摘We present a scheme to control the generated ultrafast magnetic field in H_(3)^(2+)molecules using multi-frequency tricircular pulses composed of co-and counter-rotating bicircular pulses.Simulations show that the field amplitude and the wavelength are two significant factors for magnetic field generation by tricircular pulses.Specifically,the strength of the magnetic field is linearly related to the field amplitude atλ_(0)=50 nm,while atλ_(0)=70 nm,the strength first increases and then decreases with the amplitude,this can be attributed to the resonance between the ground and excited states.Moreover,the phase and helicity of bicircular pulses are shown to have important effects on the magnetic field.The dependence of the magnetic field on the phase arises from the interference effect between multiple ionization pathways.These findings illustrate a guiding principle for controlling the magnetic field in molecular systems for future research in ultrafast magneto-optics.
基金Project supported by the National Natural Science Foundation of China(Grant No.61575077)the Natural Science Foundation of Jilin Province of China(Grant No.20180101225JC)+1 种基金the China Postdoctoral Science Foundation(Grants Nos.2018M641766 and 2019T120232)the Graduate Innovation Fund of Jilin University,China(Grant No.101832018C105)
文摘We theoretically investigate the high-order harmonic generation(HHG) of helium atom driven by bichromatic counterrotating circularly polarized laser fields. By changing the intensity ratio of the two driving laser fields, the spectral chirality of the HHG can be controlled. As the intensity ratio increases, the spectral chirality will change from positive-to negativevalue around a large intensity ratio of the two driving fields when the total laser intensity keeps unchanged. However, the sign of the spectral chirality can be changed from positive to negative around a small intensity ratio of the two driving fields when the total laser intensity changes. At this time, we can effectively control the helicity of the harmonic spectrum and the polarization of the resulting attosecond pulses by adjusting the intensity ratio of the two driving laser fields. As the intensity ratio and the total intensity of the driving laser fields increase, the relative intensity of either the left-circularly or right-circularly polarized harmonic can be enhanced. The attosecond pulses can evolve from being elliptical to near linear correspondingly.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11271158,11574117,and 61575077)the Natural Science Foundation of Jilin Province of China(Grants No.20180101225JC)
文摘By numerically solving the two-dimensional time-dependent Schr¨odinger equation under the frozen-nuclei approximation, we are able to study the molecular photoelectron-momentum distribution(MPMD) of H^+_2 with different orientation angles driven by elliptically polarized laser pulse with varying ellipticities. Our numerical results show that the MPMD is sensitive to the orientation angle and the laser ellipticity, which can be explained by the attosecond perturbation ionization theory and the exactly solvable photoionization model. When the ellipticity ε = 0, the final MPMD of x-oriented H^+_2 shows a distinct six-lobe pattern that is different from that with ε = 0.5 and ε = 1. The evolutions of electron wave packet(EWP)and MPMD with x-oriented H^+_2 are presented to interpret this distinct pattern.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074146 and 12074142)。
文摘Coherent electronic dynamics are of great significance in photo-induced processes and molecular magnetism.We theoretically investigate electronic dynamics of triatomic molecule H_(3)^(2+) by circularly polarized pulses,including electron density distributions,induced electronic currents,and ultrafast magnetic field generation.By comparing the results of the coherent resonant excitation and direct ionization,we found that for the coherent resonant excitation,the electron is localized and the coherent electron wave packet moves periodically between three protons,which can be attributed to the coherent superposition of the ground A′state and excited E+state.Whereas,for the direct single-photon ionization,the induced electronic currents mainly come from the free electron in the continuum state.It is found that there are differences in the intensity,phase,and frequency of the induced current and the generated magnetic field.The scheme allows one to control the induced electronic current and the ultrafast magnetic field generation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074146,21827805,11974007,and 12074142)the Natural Science Foundation of Jilin Province of China(Grant No.20180101225JC)。
文摘We present the photoelectron momentum distributions(PMDs) and the photoelectron angular distributions(PADs) of He+ ions, aligned H2+ molecules and N2 molecules by intense orthogonally polarized laser pulses. Simulations are performed by numerically solving the corresponding two-dimensional time-dependent Schr?dinger equations(TDSEs) within the single-electron approximation frame. Photoelectron momentum distributions and photoelectron angular distributions present different patterns with the time delays Td, illustrating the dependences of the PMDs and PADs on the time delays by orthogonally polarized laser pulses. The evolution of the electron wavepackets can be employed to describe the intensity of the PADs from the TDSE simulations for N2 molecules.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074146,11974007,12074142,11904122,91850114,and 11774131)the Natural Science Foundation of Jilin Province of China(Grant No.20180101225JC)。
文摘The ultrafast photoionization dynamics of N_(2) molecules by x-ray/XUV laser pulses is investigated.The molecular frame photoelectron momentum distributions(MF-PMDs) and the molecular frame photoelectron angular distributions(MF-PADs) are obtained by numerically solving 2D time-dependent Schrodinger equations within the single-electron approximation(SEA) frame.The results show that the molecular photoionization diffraction appears in 5 nm laser fields.However,when the laser wavelength is 30 nm,the molecular photoionization diffraction disappears and the MF-PMDs show four-lobe pattern.The ultrafast photoionization model can be employed to describe the MF-PMDs and MF-PADs of N_(2) molecules.
基金supported in part by the National Natural Science Foundation of China(#10574057,#10571074,and#10171039)by the Specialized Research Fund for the Doctoral Program of Higher Education(#20050183010).
文摘In this paper we survey recent progress in symplectic algorithms for use in quantum systems in the following topics:Symplectic schemes for solving Hamiltonian systems;Classical trajectories of diatomic systems,model molecule A2B,Hydrogen ion H+2 and elementary atmospheric reaction N(4S)+O2(X 3Σ−g)→NO(X 2Π)+O(3P)calculated by means of Runge-Kutta methods and symplectic methods;the classical dissociation of the HF molecule and classical dynamics of H+2 in an intense laser field;the symplectic form and symplectic-scheme shooting method for the time-independent Schr¨odinger equation;the computation of continuum eigenfunction of the Schr¨odinger equation;asymptotic boundary conditions for solving the time-dependent Schr¨odinger equation of an atom in an intense laser field;symplectic discretization based on asymptotic boundary condition and the numerical eigenfunction expansion;and applications in computing multi-photon ionization,above-threshold ionization,Rabbi oscillation and high-order harmonic generation of laser-atom interaction.
基金This work was supported by the National Natural Science Foundation of China(Grants No.12074142).
文摘We theoretically investigate the vortex patterns in photoelectron momentum distributions of He^(+)driven by counter-rotating elliptically polarized,time delayed attosecond laser pulses by numerically solving the two-dimensional time-dependent Schrodinger equation.It is found that the number of vortex arms is extremely sensitive to the ellipticity and wavelength of counterrotating elliptically polarized laser pulses,which is illustrated by the attosecond perturbation ionization models.In addition,the effect of different time delays between two pulses on the interference patterns is also investigated and the corresponding physical mechanism is demonstrated.Since the wavelength,ellipticity and time delay have a significant effect on the vortex interference patterns,this may be a new method for laser field detection.