High-order harmonics from helium atom in the orthogonally two-color(OTC) laser field are investigated by solving the two-dimensional time-dependent Schrodinger equation.Non-integer high-order harmonics are obtained in...High-order harmonics from helium atom in the orthogonally two-color(OTC) laser field are investigated by solving the two-dimensional time-dependent Schrodinger equation.Non-integer high-order harmonics are obtained in some ratio of frequencies of two components.Pure odd and even harmonics from atoms could be separated in two components by adjusting the ratio of frequencies in OTC scheme,and the resolution of harmonics is improved at the same time.The physical mechanism is explained by the periodicity of dipole.With the same intensity of the incident laser,the intensity of the high-order harmonics from the OTC field scheme is improved by three orders of magnitude compared to the monochromatic laser field scheme.A theoretical scheme is provided for experimentally achieving improving energy resolution and separation of pure odd and even harmonics in atoms.Also,we provide a means for improving harmonic intensity.展开更多
We theoretically investigate the high-order-harmonic generation from the H2^＋ molecular ion exposed to the combi- nation of an intense trapezoidal laser and a static field. The results show that the harmonic spectrum...We theoretically investigate the high-order-harmonic generation from the H2^＋ molecular ion exposed to the combi- nation of an intense trapezoidal laser and a static field. The results show that the harmonic spectrum is obviously extended and the short quantum path is selected to contribute to the spectrum, because the corresponding long path is seriously suppressed. Then the combined Coulomb and laser field potentials and the time-dependent electron wave packet distributions are applied to illustrate the physical mechanism of high-order harmonic gen- eration. Finally, by adjusting the intensity of the static field and superposing a properly selected range of the HHG spectrum, a 90-as isolated attosecond pulse is straightforwardly obtained.展开更多
Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems.For the integrable situation in the thermodynamic limit,the generalized Gibbs ensemble can effectively describe t...Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems.For the integrable situation in the thermodynamic limit,the generalized Gibbs ensemble can effectively describe the energylevel occupations for the quench within the normal phase,but it fails for the quench to the superradiant phase.For the finite systems which are considered non-integrable,the post quench systems were studied by comparing with the thermal ensembles.The canonical ensembles are directly available for the quench within the normal phase.With the increasing of the target coupling strength over the equilibrium phase transition critical point,sudden changes take place for the effective temperature and the distance to the thermal ensembles.The thermalization was also studied by comparing with the results of the microcanonical ensembles.展开更多
The two-dimensional magnetic van der Waals heterojunctions have opened unprecedented opportunities to explore new physics due to their potential for spintronic applications.Here,combing density functional theory with ...The two-dimensional magnetic van der Waals heterojunctions have opened unprecedented opportunities to explore new physics due to their potential for spintronic applications.Here,combing density functional theory with non-equilibrium Green’s function technique.展开更多
The wave packet dynamics of I2^- anions is studied by using the time-dependent wave packet method. Two conclusions can be drawn from the calculations. First, the period of the total photoelectron signal oscillating wi...The wave packet dynamics of I2^- anions is studied by using the time-dependent wave packet method. Two conclusions can be drawn from the calculations. First, the period of the total photoelectron signal oscillating with the propagation of delay time is about 750fs. Second, the photoionization of I2^- anions begin at the time 600 fs, and the time needed for the population of the electronic state of I2 neutral molecule to reach the maximum becomes shorter with the increasing delay time.展开更多
The spatial distribution in high-order harmonic generation（HHG） is theoretically investigated by using a few-cycle laser pulse from a two-dimensional model of a hydrogen molecular ion. The spatial distribution in HH...The spatial distribution in high-order harmonic generation（HHG） is theoretically investigated by using a few-cycle laser pulse from a two-dimensional model of a hydrogen molecular ion. The spatial distribution in HHG demonstrates that the harmonic spectra are sensitive to the carrier envelope phase and the duration of the laser pulse. The HHG can be restrained by a pulse with the duration of 5 fs in the region from the 90 th to 320th order. This characteristic is illustrated by the probability density of electron wave packet distribution. The electron is mainly located near the nucleus along the positive-x direction from 3.0 o.c. to 3.2 o.c., which is an important time to generate the HHG in the plateau area. We also demonstrate the time-frequency distribution in the region of the positive-and negative-x direction to explain the physical mechanism.展开更多
The polarization properties of high-order harmonic generation(HHG) in the two-color circularly polarized laser fields are investigated by numerically solving the two-dimensional time-dependent Schr?dinger equation. By...The polarization properties of high-order harmonic generation(HHG) in the two-color circularly polarized laser fields are investigated by numerically solving the two-dimensional time-dependent Schr?dinger equation. By adding a wavelength of 1600-nm right-circular-polarized field to an 800-nm left-circular-polarized field, HHG is simulated from a real model of neon atom with p orbital, but not from a hydrogen-like atom model with s orbital. The orders of 3n + 1 can be selected while the orders of 3n + 2 are suppressed by adjusting the intensities of the two pulses. The physical mechanism is analyzed by time-frequency analysis and semiclassical model.展开更多
The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schrtdinger equation and the classical ...The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schrtdinger equation and the classical equation of motion. By establishing the physical model of the harmonic emission in the inhomogeneous field, we discuss the related characters of the multiple rescatterings process in the harmonic generation process. It shows that the second rescattering rather than the first rescattering tends to determine the harmonic cutoff energy when the inhomogeneous parameter is larger than 0.0055. Additionally, with the classica/simulation, the underlying physical mechanism of the continuum-continuum harmonics is also revealed. Moreover, this work may provide new physical insight into the harmonic generation in an inhomogeneous field, and is beneficial to further extract the harnaonic emission from molecular systems.展开更多
We propose an efficient method for the generation of an isolated attosecond pulse from the asymmetric molecular ions HeH^2＋ by adding a half-cycle-like field （HCLF） to the fundamental driving laser field. The high-...We propose an efficient method for the generation of an isolated attosecond pulse from the asymmetric molecular ions HeH^2＋ by adding a half-cycle-like field （HCLF） to the fundamental driving laser field. The high-order harmonic generation （HHG） is investigated by numerically sowing the time-dependent Schrodinger equation. By performing the time-frequency distributions and the electronic wave packet probability densities, we find that the optimizing combined field is not only useful for extending the HHG cutoff, but also for simplifying the recombination channels through controlling the electron localization. In addition, by adjusting the intensity of the HCLF, a dominant short quantum path is selected to contribute the HHG spectrum. As a result, a 75-as isolated attosecond pulse is obtained by superposing a proper range of the harmonics.展开更多
The two-color circularly polarized pulses scheme was proposed to generate isolated attosecond pulses in our previous work [Phys. Rev. A 87 （2013） 043406], while the polarization of the attosecond pulse was not inves...The two-color circularly polarized pulses scheme was proposed to generate isolated attosecond pulses in our previous work [Phys. Rev. A 87 （2013） 043406], while the polarization of the attosecond pulse was not investigated. We show a supplementary explanation of this scheme and present another scheme to generate linear isolated attosecond pulses by combining a circularly polarized pulse with an elliptically polarized pulse. High-order harmonic generation and quantum path control are investigated to compare these two schemes. Both schemes can obtain supercontinuum spectra plateau from about 200eV to 550eV, which belong to the water window region. It is found that the latter scheme can clearly eliminate the short quantum path and extend the harmonic plateau. A linear isolated attosecond pulse with a duration of sub-6Oas can be generated by superposing a bandwidth of 70eV.展开更多
The dependence of harmonic emission from a solid on the carrier envelope phase (CEP) is discussed by numerically solving the time-dependent Schr?dinger equation. The harmonic spectra periodically exhibit three distinc...The dependence of harmonic emission from a solid on the carrier envelope phase (CEP) is discussed by numerically solving the time-dependent Schr?dinger equation. The harmonic spectra periodically exhibit three distinct oscillating structures, which indicate the different dependences of the cutoff energies on the CEP. Furthermore,with time-dependent population imaging and the populations of different energy bands, the underlying physical mechanism is explored.展开更多
Controlling paths of high-order harmonic generation from H^2+ is theoretically investigated by numerically solving the time-dependent Schrodinger equation based on the Born-Oppenheimer approximation in orthogonal two-...Controlling paths of high-order harmonic generation from H^2+ is theoretically investigated by numerically solving the time-dependent Schrodinger equation based on the Born-Oppenheimer approximation in orthogonal two-color fields.Our simulations show that the change of harmonic emission paths is dependent on time-dependent distribution of electrons.Compared with one-dimensional linearly polarized long wavelength laser,multiple returns are suppressed and short paths are dominant in the process of harmonic emission by two-dimensional orthogonal ω/2ω laser fields.Furthermore,not only are multiple returns weaken,but also the harmonic emission varies from twice to once in an optical cycle by orthogonalω/1.5ωlaser fields.Combining the time-frequency distributions and the time-dependent electron wave packets probability density,the mechanism of controlling paths is further explained.As a result,a 68-as isolated attosecond pulse is obtained by superposing a proper range of the harmonics.展开更多
We theoretically investigate the electron localization around two nuclei in harmonic emission from asymmetric molecular ion. The results show that the ionization process of electron localized around one nucleus compet...We theoretically investigate the electron localization around two nuclei in harmonic emission from asymmetric molecular ion. The results show that the ionization process of electron localized around one nucleus competes with its transfer process to the other nucleus. By increasing the initial vibrational level, more electrons localized around the nucleus D＋ tend to transfer to the nucleus He2＋ so that the ionizations of electrons localized around the nucleus He2＋ increase. In this case, the difference in harmonic efficiency between Hell2＋ and HeD2＋ decreases while the difference in harmonic spectral structure increases. The evident minimum can be observed the spectral structure of HeD2＋, which is due to the strong in the harmonic spectrum of Hell2＋ compared with that in interference of multiple recombination channels originating from two nuclei. Time-dependent nuclear probability density, electron-nuclear probability density, double-well model, and time-frequency maps are presented to explain the underlying mechanisms.展开更多
The quantum effect of nonlinear co-tunnelling process, which is dependent on atom-pair tunneling and asymmetry of an double-well trap, is studied by using an asymmetrical extended Bose–Hubbard model. Due to the exist...The quantum effect of nonlinear co-tunnelling process, which is dependent on atom-pair tunneling and asymmetry of an double-well trap, is studied by using an asymmetrical extended Bose–Hubbard model. Due to the existence of atompair tunneling that describes quantum phenomena of ultracold atom-gas clouds in an asymmetrical double-well trap, the asymmetrical extended Bose–Hubbard model is better than the previous Bose–Hubbard model model by comparing with the experimental data cited from the literature. The dependence of dynamics and quantum phase transition on atom-pair tunneling and asymmetry are investigated. Importantly, it shows that the asymmetry of the extended Bose–Hubbard model,corresponding to the bias between double wells, leads to a number of resonance tunneling processes, which tunneling is renamed conditional resonance tunneling, and corrects the atom-number parity effect by controlling the bias between double wells.展开更多
We theoretically investigate the high-order harmonic generation of the one-dimensional hydrogen molecular ion at fixed intermediate internuclear distance, driven by a multicycle laser field. Our results show that the ...We theoretically investigate the high-order harmonic generation of the one-dimensional hydrogen molecular ion at fixed intermediate internuclear distance, driven by a multicycle laser field. Our results show that the initial electronic state of the hydrogen molecular ion affects the modulation of the high-order harmonic spectrum, especially the positions of the minima. Based on the two-state model, the underlying physical mechanism of the minimum is analyzed and discussed. Further analysis shows that the different positions of the minima in the different initial electronic states can be understood via the different interferences of the two phase-adiabatic states at the ionization times.展开更多
Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended B...Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended Bose–Hubbard model after a global interaction quench by considering several observables: the local Boson numbers, the nonlocal entanglement entropy, and the momentum distribution functions. We calculate the thermalization fidelity for different quench parameters and different sizes of subsystems, and the results show that the degree of thermalization is affected by the distance from the integrable point and the size of the subsystem. We employ the Pearson coefficient as the measurement of the correlation between the entanglement entropy and thermalization fidelity, and a strong correlation is demonstrated for the quenched system.展开更多
The attosecond ionization dynamics of atoms has attracted extensive attention in these days.However,the role of the initial state is not clearly understood.To address this question,we perform simulations on the neon a...The attosecond ionization dynamics of atoms has attracted extensive attention in these days.However,the role of the initial state is not clearly understood.To address this question,we perform simulations on the neon atom and its model atom with different initial states by numerically solving the corresponding two-dimensional time-dependent Schrodinger¨equations.We theoretically investigate atomic photoelectron momentum distributions(PMDs)by a pair of elliptically polarized attosecond laser pulses.We find that the PMD is sensitive not only to the ellipticities of the pulses,the relative helicity,and time delay of the pulses,but also to the symmetry of the initial electronic states.Results are analyzed by the first-order time-dependent perturbation theory(TDPT)and offer a new tool for detecting the rotation direction of the ring currents.展开更多
The isotopic effect on nuclear dynamics in Coulomb explosion for various initial vibrational states of H_(2)^(+) and HD+in intense laser(80 fs,800 nm,I=6.8×10^(13)W/cm^(2)) is theoretically investigated by numeri...The isotopic effect on nuclear dynamics in Coulomb explosion for various initial vibrational states of H_(2)^(+) and HD+in intense laser(80 fs,800 nm,I=6.8×10^(13)W/cm^(2)) is theoretically investigated by numerically solving the time-dependent Schrodinger equation.The calculated results confirm that the effect we discussed by paying close attention to the comparative analysis of peak locations in the nuclear kinetic-energy-release spectra largely depends on the selection of the initial vibrational states.Furthermore,it is the special isotope effect case about the vibrational state v=5 that has been studied in depth.We also discuss the time-dependent spectrum atυ=7,which can reveal the difference in nuclear wavepacket motion between H_(2)^(+) and HD+in the time region in which charge-resonance enhanced ionization takes place.展开更多
By numerically solving the non-Born–Oppenheimer time-dependent Schr?dinger equation in a few-cycle chirped laser field(5-fs,800-nm),the effect of the permanent dipole moment on the Coulomb explosion is studied by the...By numerically solving the non-Born–Oppenheimer time-dependent Schr?dinger equation in a few-cycle chirped laser field(5-fs,800-nm),the effect of the permanent dipole moment on the Coulomb explosion is studied by the kinetic-energy-release spectra with the"virtual detector"method.The results indicate that with the effect of the permanent dipole moment,different multiphoton processes for heteronuclear and homonuclear diatomic molecular ions may take place when the wave packets transit from the ground state(1sσg)to the first excited state(2pσu),and then move along the excited potential curve,and finally charge-resonant enhanced ionization occurs at critical internuclear distance.As a result,despite the similar ionization probabilities for these two systems at higher vibrational level with larger chirp parameterβ,the structure of the Coulomb explosion spectrum for the former is prominently different from that for the latter.展开更多
The effect of final-state dynamic correlation is investigated for ionization of atomic hydrogen by 75-keV proton impact by analyzing double differential cross sections.The final state is represented by a continuum cor...The effect of final-state dynamic correlation is investigated for ionization of atomic hydrogen by 75-keV proton impact by analyzing double differential cross sections.The final state is represented by a continuum correlated wave(CCW-PT)function which accounts for the interaction between the projectile and the target nucleus(PT interaction).The correlated final state is nonseparable solutions of the wave equation combining the dynamics of the electron motion relative to the target and projectile,satisfying the Redmond’s asymptotic conditions corresponding to long range interactions.The transition matrix is evaluated using the CCW-PT function and the undistorted initial state.Both the correlation effects and the PT interaction are analyzed by the present calculations.The convergence of the continuous correlated final state is examined carefully.Our results are compared with the absolute experimental data measured by Laforge et al.[Phys.Rev.Lett.103,053201(2009)]and Schulz et al.[Phys.Rev.A 81,052705(2010)],as well as other theoretical models(especially the results of the latest non perturbation theory).We have shown that the dynamic correlation plays an important role in the ionization of atomic hydrogen by proton impact.While overall agreement between theory and the experimental data is encouraging,detailed agreement is still lacking.However,such an analysis is meaningful because it provides valuable information about the dynamical correlation and PT interaction in the CCW-PT theoretical model.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974229 and 11504221)the Natural Science Foundation of Shanxi Province+4 种基金China(Grant No.201901D111288)the Scientific and Technological Innovation Programs of Higher Education Institutions in ShanxiChina(Grant No.2019L0452)the Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi ProvinceChina。
文摘High-order harmonics from helium atom in the orthogonally two-color(OTC) laser field are investigated by solving the two-dimensional time-dependent Schrodinger equation.Non-integer high-order harmonics are obtained in some ratio of frequencies of two components.Pure odd and even harmonics from atoms could be separated in two components by adjusting the ratio of frequencies in OTC scheme,and the resolution of harmonics is improved at the same time.The physical mechanism is explained by the periodicity of dipole.With the same intensity of the incident laser,the intensity of the high-order harmonics from the OTC field scheme is improved by three orders of magnitude compared to the monochromatic laser field scheme.A theoretical scheme is provided for experimentally achieving improving energy resolution and separation of pure odd and even harmonics in atoms.Also,we provide a means for improving harmonic intensity.
基金Supported by the National Natural Science Foundation of China under Grant No 11404204the Key Project of the Ministry of Education of China under Grant No 211025+1 种基金the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20111404120004the Natural Science Foundation for Young Scientists of Shanxi Province of China under Grant No2009021005
文摘We theoretically investigate the high-order-harmonic generation from the H2^＋ molecular ion exposed to the combi- nation of an intense trapezoidal laser and a static field. The results show that the harmonic spectrum is obviously extended and the short quantum path is selected to contribute to the spectrum, because the corresponding long path is seriously suppressed. Then the combined Coulomb and laser field potentials and the time-dependent electron wave packet distributions are applied to illustrate the physical mechanism of high-order harmonic gen- eration. Finally, by adjusting the intensity of the static field and superposing a properly selected range of the HHG spectrum, a 90-as isolated attosecond pulse is straightforwardly obtained.
基金Project supported by the National Natural Science Foundation of China(Grant No.11147110)the Natural Science Youth Foundation of Shanxi,China(Grant No.2011021003)。
文摘Quantum quenches in the Dicke model were studied both in the thermodynamic limit and the finite systems.For the integrable situation in the thermodynamic limit,the generalized Gibbs ensemble can effectively describe the energylevel occupations for the quench within the normal phase,but it fails for the quench to the superradiant phase.For the finite systems which are considered non-integrable,the post quench systems were studied by comparing with the thermal ensembles.The canonical ensembles are directly available for the quench within the normal phase.With the increasing of the target coupling strength over the equilibrium phase transition critical point,sudden changes take place for the effective temperature and the distance to the thermal ensembles.The thermalization was also studied by comparing with the results of the microcanonical ensembles.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB3505301)the Natural Science Basic Research Program of Shanxi(Grant No.20210302124252)the Innovation Project For Teaching Reform of Shanxi(Grant No.J20230616)。
文摘The two-dimensional magnetic van der Waals heterojunctions have opened unprecedented opportunities to explore new physics due to their potential for spintronic applications.Here,combing density functional theory with non-equilibrium Green’s function technique.
基金Supported by the National Natural Science Foundation of China under Grant No 10575017. The code used in our calculation is provided by Professor Ke-Li Han and we appreciate his help and kind advice.
文摘The wave packet dynamics of I2^- anions is studied by using the time-dependent wave packet method. Two conclusions can be drawn from the calculations. First, the period of the total photoelectron signal oscillating with the propagation of delay time is about 750fs. Second, the photoionization of I2^- anions begin at the time 600 fs, and the time needed for the population of the electronic state of I2 neutral molecule to reach the maximum becomes shorter with the increasing delay time.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504221,61575077,11404204,and 11447208)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2015021023)Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,China
文摘The spatial distribution in high-order harmonic generation（HHG） is theoretically investigated by using a few-cycle laser pulse from a two-dimensional model of a hydrogen molecular ion. The spatial distribution in HHG demonstrates that the harmonic spectra are sensitive to the carrier envelope phase and the duration of the laser pulse. The HHG can be restrained by a pulse with the duration of 5 fs in the region from the 90 th to 320th order. This characteristic is illustrated by the probability density of electron wave packet distribution. The electron is mainly located near the nucleus along the positive-x direction from 3.0 o.c. to 3.2 o.c., which is an important time to generate the HHG in the plateau area. We also demonstrate the time-frequency distribution in the region of the positive-and negative-x direction to explain the physical mechanism.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974229,11504221,and 11404204)the Scientific and Technological Innovation Program of Higher Education Institutions in Shanxi Province,China(Grant No.2019L0452)+1 种基金the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2015021023)the Program for Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,China
文摘The polarization properties of high-order harmonic generation(HHG) in the two-color circularly polarized laser fields are investigated by numerically solving the two-dimensional time-dependent Schr?dinger equation. By adding a wavelength of 1600-nm right-circular-polarized field to an 800-nm left-circular-polarized field, HHG is simulated from a real model of neon atom with p orbital, but not from a hydrogen-like atom model with s orbital. The orders of 3n + 1 can be selected while the orders of 3n + 2 are suppressed by adjusting the intensities of the two pulses. The physical mechanism is analyzed by time-frequency analysis and semiclassical model.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404204,11274215,and 11504221)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2015021023)+1 种基金Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,ChinaInnovation Project for Postgraduates of Shanxi Province,China(Grant No.2017BY085)
文摘The effect of multiple rescattering processes on the harmonic emission from He atom in a spatially inhomogeneous field is discussed by solving the one-dimensional time-dependent Schrtdinger equation and the classical equation of motion. By establishing the physical model of the harmonic emission in the inhomogeneous field, we discuss the related characters of the multiple rescatterings process in the harmonic generation process. It shows that the second rescattering rather than the first rescattering tends to determine the harmonic cutoff energy when the inhomogeneous parameter is larger than 0.0055. Additionally, with the classica/simulation, the underlying physical mechanism of the continuum-continuum harmonics is also revealed. Moreover, this work may provide new physical insight into the harmonic generation in an inhomogeneous field, and is beneficial to further extract the harnaonic emission from molecular systems.
基金Supported by the National Natural Science Foundation of China under Grant No 11404204the Key Project of the Ministry of Education of China under Grant No 211025+1 种基金the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20111404120004the Natural Science Foundation for Young Scientists of Shanxi Province under Grant No 2009021005
文摘We propose an efficient method for the generation of an isolated attosecond pulse from the asymmetric molecular ions HeH^2＋ by adding a half-cycle-like field （HCLF） to the fundamental driving laser field. The high-order harmonic generation （HHG） is investigated by numerically sowing the time-dependent Schrodinger equation. By performing the time-frequency distributions and the electronic wave packet probability densities, we find that the optimizing combined field is not only useful for extending the HHG cutoff, but also for simplifying the recombination channels through controlling the electron localization. In addition, by adjusting the intensity of the HCLF, a dominant short quantum path is selected to contribute the HHG spectrum. As a result, a 75-as isolated attosecond pulse is obtained by superposing a proper range of the harmonics.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11404204 and 11447208the Key Project of Chinese Ministry of Education under Grant No 211025+1 种基金the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20111404120004the Natural Science Foundation for Young Scientists of Shanxi Province under Grant No 2009021005
文摘The two-color circularly polarized pulses scheme was proposed to generate isolated attosecond pulses in our previous work [Phys. Rev. A 87 （2013） 043406], while the polarization of the attosecond pulse was not investigated. We show a supplementary explanation of this scheme and present another scheme to generate linear isolated attosecond pulses by combining a circularly polarized pulse with an elliptically polarized pulse. High-order harmonic generation and quantum path control are investigated to compare these two schemes. Both schemes can obtain supercontinuum spectra plateau from about 200eV to 550eV, which belong to the water window region. It is found that the latter scheme can clearly eliminate the short quantum path and extend the harmonic plateau. A linear isolated attosecond pulse with a duration of sub-6Oas can be generated by superposing a bandwidth of 70eV.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11404204 and 11504221the Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province+1 种基金the Natural Science Foundation for Young Scientists of Shanxi Normal University under Grant No ZR1805the Project for Graduate Research Innovation of Shanxi Normal University
文摘The dependence of harmonic emission from a solid on the carrier envelope phase (CEP) is discussed by numerically solving the time-dependent Schr?dinger equation. The harmonic spectra periodically exhibit three distinct oscillating structures, which indicate the different dependences of the cutoff energies on the CEP. Furthermore,with time-dependent population imaging and the populations of different energy bands, the underlying physical mechanism is explored.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974229,11404204,and 11947002)the Scientific and Technological Innovation Program of Higher Education Institutions in Shanxi Province,China(Grant No.2019L0468)+1 种基金the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.201901D211404)the Innovation Project for Postgraduates of Shanxi Province,China(Grant No.2019SY310)。
文摘Controlling paths of high-order harmonic generation from H^2+ is theoretically investigated by numerically solving the time-dependent Schrodinger equation based on the Born-Oppenheimer approximation in orthogonal two-color fields.Our simulations show that the change of harmonic emission paths is dependent on time-dependent distribution of electrons.Compared with one-dimensional linearly polarized long wavelength laser,multiple returns are suppressed and short paths are dominant in the process of harmonic emission by two-dimensional orthogonal ω/2ω laser fields.Furthermore,not only are multiple returns weaken,but also the harmonic emission varies from twice to once in an optical cycle by orthogonalω/1.5ωlaser fields.Combining the time-frequency distributions and the time-dependent electron wave packets probability density,the mechanism of controlling paths is further explained.As a result,a 68-as isolated attosecond pulse is obtained by superposing a proper range of the harmonics.
基金Project supported by the National Natural Science Foundation of China(Grant No.11404204)the Key Project of Chinese Ministry of Education(Grant No.211025)+2 种基金the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20111404120004)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.2009021005)the Innovation Project for Postgraduates of Shanxi Province,China(Grant No.20133081)
文摘We theoretically investigate the electron localization around two nuclei in harmonic emission from asymmetric molecular ion. The results show that the ionization process of electron localized around one nucleus competes with its transfer process to the other nucleus. By increasing the initial vibrational level, more electrons localized around the nucleus D＋ tend to transfer to the nucleus He2＋ so that the ionizations of electrons localized around the nucleus He2＋ increase. In this case, the difference in harmonic efficiency between Hell2＋ and HeD2＋ decreases while the difference in harmonic spectral structure increases. The evident minimum can be observed the spectral structure of HeD2＋, which is due to the strong in the harmonic spectrum of Hell2＋ compared with that in interference of multiple recombination channels originating from two nuclei. Time-dependent nuclear probability density, electron-nuclear probability density, double-well model, and time-frequency maps are presented to explain the underlying mechanisms.
基金Project supported by the National Natural Science Foundation of China(Grant No.11075099)
文摘The quantum effect of nonlinear co-tunnelling process, which is dependent on atom-pair tunneling and asymmetry of an double-well trap, is studied by using an asymmetrical extended Bose–Hubbard model. Due to the existence of atompair tunneling that describes quantum phenomena of ultracold atom-gas clouds in an asymmetrical double-well trap, the asymmetrical extended Bose–Hubbard model is better than the previous Bose–Hubbard model model by comparing with the experimental data cited from the literature. The dependence of dynamics and quantum phase transition on atom-pair tunneling and asymmetry are investigated. Importantly, it shows that the asymmetry of the extended Bose–Hubbard model,corresponding to the bias between double wells, leads to a number of resonance tunneling processes, which tunneling is renamed conditional resonance tunneling, and corrects the atom-number parity effect by controlling the bias between double wells.
基金supported by the National Natural Science Foundation of China(Grant No.11404204)the Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,China
文摘We theoretically investigate the high-order harmonic generation of the one-dimensional hydrogen molecular ion at fixed intermediate internuclear distance, driven by a multicycle laser field. Our results show that the initial electronic state of the hydrogen molecular ion affects the modulation of the high-order harmonic spectrum, especially the positions of the minima. Based on the two-state model, the underlying physical mechanism of the minimum is analyzed and discussed. Further analysis shows that the different positions of the minima in the different initial electronic states can be understood via the different interferences of the two phase-adiabatic states at the ionization times.
基金supported by the National Natural Science Foundation of China (Grant No. 11147110)the Natural Science Youth Foundation of Shanxi Province, China (Grant No. 2011021003)。
文摘Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended Bose–Hubbard model after a global interaction quench by considering several observables: the local Boson numbers, the nonlocal entanglement entropy, and the momentum distribution functions. We calculate the thermalization fidelity for different quench parameters and different sizes of subsystems, and the results show that the degree of thermalization is affected by the distance from the integrable point and the size of the subsystem. We employ the Pearson coefficient as the measurement of the correlation between the entanglement entropy and thermalization fidelity, and a strong correlation is demonstrated for the quenched system.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404204 and 11974229)the Natural Science Foundation for Young Scientists of Shanxi Province,China(Grant No.201901D211404)+1 种基金the Scientific and Technological Innovation Program of Higher Education Institutions in Shanxi Province,China(Grant No.2019L0468)the Project of Excellent Course of Shanxi Normal University,China(Grant No.2017YZKC-35).
文摘The attosecond ionization dynamics of atoms has attracted extensive attention in these days.However,the role of the initial state is not clearly understood.To address this question,we perform simulations on the neon atom and its model atom with different initial states by numerically solving the corresponding two-dimensional time-dependent Schrodinger¨equations.We theoretically investigate atomic photoelectron momentum distributions(PMDs)by a pair of elliptically polarized attosecond laser pulses.We find that the PMD is sensitive not only to the ellipticities of the pulses,the relative helicity,and time delay of the pulses,but also to the symmetry of the initial electronic states.Results are analyzed by the first-order time-dependent perturbation theory(TDPT)and offer a new tool for detecting the rotation direction of the ring currents.
基金Supported by the Special Funds of the National Natural Science Foundation of China(No 11047191)Key Project of the Ministry of Education of China(No 211025)+1 种基金Research Fund for the Doctoral Program of Higher Education of China(No 20111404120004)the Natural Science Foundation for Young Scientists of Shanxi Province(No 2009021005).
文摘The isotopic effect on nuclear dynamics in Coulomb explosion for various initial vibrational states of H_(2)^(+) and HD+in intense laser(80 fs,800 nm,I=6.8×10^(13)W/cm^(2)) is theoretically investigated by numerically solving the time-dependent Schrodinger equation.The calculated results confirm that the effect we discussed by paying close attention to the comparative analysis of peak locations in the nuclear kinetic-energy-release spectra largely depends on the selection of the initial vibrational states.Furthermore,it is the special isotope effect case about the vibrational state v=5 that has been studied in depth.We also discuss the time-dependent spectrum atυ=7,which can reveal the difference in nuclear wavepacket motion between H_(2)^(+) and HD+in the time region in which charge-resonance enhanced ionization takes place.
基金Supported by the National Natural Science Foundation of China under Grant No 11047191the Key Project of the Ministry of Education of China under Grant No 211025+1 种基金the Research Fund for the Doctoral Program of Higher Education of China under Grant No 20111404120004the Natural Science Foundation for Young Scientists of Shanxi Province under Grant No 2009021005.
文摘By numerically solving the non-Born–Oppenheimer time-dependent Schr?dinger equation in a few-cycle chirped laser field(5-fs,800-nm),the effect of the permanent dipole moment on the Coulomb explosion is studied by the kinetic-energy-release spectra with the"virtual detector"method.The results indicate that with the effect of the permanent dipole moment,different multiphoton processes for heteronuclear and homonuclear diatomic molecular ions may take place when the wave packets transit from the ground state(1sσg)to the first excited state(2pσu),and then move along the excited potential curve,and finally charge-resonant enhanced ionization occurs at critical internuclear distance.As a result,despite the similar ionization probabilities for these two systems at higher vibrational level with larger chirp parameterβ,the structure of the Coulomb explosion spectrum for the former is prominently different from that for the latter.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974229 and 11274215)。
文摘The effect of final-state dynamic correlation is investigated for ionization of atomic hydrogen by 75-keV proton impact by analyzing double differential cross sections.The final state is represented by a continuum correlated wave(CCW-PT)function which accounts for the interaction between the projectile and the target nucleus(PT interaction).The correlated final state is nonseparable solutions of the wave equation combining the dynamics of the electron motion relative to the target and projectile,satisfying the Redmond’s asymptotic conditions corresponding to long range interactions.The transition matrix is evaluated using the CCW-PT function and the undistorted initial state.Both the correlation effects and the PT interaction are analyzed by the present calculations.The convergence of the continuous correlated final state is examined carefully.Our results are compared with the absolute experimental data measured by Laforge et al.[Phys.Rev.Lett.103,053201(2009)]and Schulz et al.[Phys.Rev.A 81,052705(2010)],as well as other theoretical models(especially the results of the latest non perturbation theory).We have shown that the dynamic correlation plays an important role in the ionization of atomic hydrogen by proton impact.While overall agreement between theory and the experimental data is encouraging,detailed agreement is still lacking.However,such an analysis is meaningful because it provides valuable information about the dynamical correlation and PT interaction in the CCW-PT theoretical model.
