The Autler-Townes （AT） splitting in femtosecond photoelectron spectrum of three-level Li2 molecules is theoretically investigated using time-dependent quantum wave packet method. With proper femtosecond laser pulses...The Autler-Townes （AT） splitting in femtosecond photoelectron spectrum of three-level Li2 molecules is theoretically investigated using time-dependent quantum wave packet method. With proper femtosecond laser pulses, three peaks of the AT splitting can be observed in the photoelectron spectrum. The AT splitting stems from rapid Rabi oscillation caused by intense ultrashort laser pluses. The effects of laser parameters on the molecular ionization dynamics are also discussed.展开更多
The effect of pulse temporal profiles on the Autler-Townes （AT） splitting in photoelectron spectra is theoretically studied by employing the time-dependent wave packet method for a rotational Na2 molecule. The AT sp...The effect of pulse temporal profiles on the Autler-Townes （AT） splitting in photoelectron spectra is theoretically studied by employing the time-dependent wave packet method for a rotational Na2 molecule. The AT splitting which results from the sufficient Rabi oscillations is affected by the pulse profile and molecular alignment. The AT splitting may be observed only by utilizing proper pulse profiles with a certain intensity.展开更多
Position-dependent-mass systems are of great importance in many physical situations,such as the transport of charge carriers in semiconductors with non-uniform composition and in the theory of many-body interactions i...Position-dependent-mass systems are of great importance in many physical situations,such as the transport of charge carriers in semiconductors with non-uniform composition and in the theory of many-body interactions in condensed matter.Here we investigate,numerically and analytically,the phenomenon of fractional revivals in such systems,which is a generic characteristic manifested by the wave-packet evolution in bounded Hamiltonian systems.Identifying the fractional revivals using specific probes is an important task in the theory of quantum measurement and sensing.We numerically simulate the temporal evolution of probability density and information entropy density,which manifest self-similarly recurring interference patterns,namely,quantum carpets.Our numerical results show that the quantum carpets not only serve as an effective probe for recognizing the fractional revivals of various order but they efficiently describe the effect of spatially-varying mass on the structure of fractional revivals,which is manifested as a symmetry breaking in their designs.展开更多
We analytically and numerically investigate the dynamical properties of the tilted dispersion relativistic quasiparticles emerged in a cold atomic optical lattice system.By introducing the next nearest neighboring(NNN...We analytically and numerically investigate the dynamical properties of the tilted dispersion relativistic quasiparticles emerged in a cold atomic optical lattice system.By introducing the next nearest neighboring(NNN)hopping term into Su-Schrieffer-Heeger(SSH)model,the Dirac quasiparticles with tilted dispersion relation are realized.The results show that the tilted dispersion causes a drift in relativistic quasiparticles rather than affecting interference behavior between inner states.To be specific,the relativistic phenomena of the quasiparticles induced by the inner state interference(such as Zitterbewegung,Klein paradox,etc.)is completely unaffected by the tilted dispersion.In order to distinguish the drift induced by tilted dispersion and common initial velocity,we calculate the momentum distribution of the relativistic quasiparticles.We obtain the difference between the drift induced by initial velocity and tilted dispersion.The former affects the ZB,while the latter does not.By using this character,we propose a quench dynamics scheme to obtain a stable mono-spin state.The proposed cold atomic lattice system would provide a promising platform in exploring the intrinsic exotic physics of relativistic quasiparticles and the related systems.展开更多
In the special theory of relativity, massive particles can travel at neither the speed of light c nor faster. Meanwhile, since the photon was quantized, many have thought of it as a point particle. How pointed? The id...In the special theory of relativity, massive particles can travel at neither the speed of light c nor faster. Meanwhile, since the photon was quantized, many have thought of it as a point particle. How pointed? The idea could be a mathematical device or physical simplification. By contrast, the preceding notion of wave-group duality has two velocities: a group velocity vg and a phase velocity vp. In light vp = vg = c;but it follows from special relativity that, in massive particles, vp > c. The phase velocity is the product of the two best measured variables, and so their product constitutes internal motion that travels, verifiably, faster than light. How does vp then appear in Minkowski space? For light, the spatio-temporal Lorentz invariant metric is s2=c2t2−x2−y2−z2, the same in whatever frame it is viewed. The space is divided into 3 parts: firstly a cone, symmetric about the vertical axis ct > 0 that represents the world line of a stationary particle while the conical surface at s = 0 represents the locus for light rays that travel at the speed of light c. Since no real thing travels faster than the speed of light c, the surface is also a horizon for what can be seen by an observer starting from the origin at time t = 0. Secondly, an inverted cone represents, equivalently, time past. Thirdly, outside the cones, inaccessible space. The phase velocity vp, group velocity vg and speed of light are all equal in free space, vp = vg = c, constant. By contrast, for particles, where causality is due to particle interactions having rest mass mo > 0, we have to employ the Klein-Gordon equation with s2=c2t2−x2−y2−z2+mo2c2. Now special relativity requires a complication: vp.vg = c2 where vg c and therefore vp > c. In the volume outside the cones, causality due to light interactions cannot extend beyond the cones. However, since vp > c and even vp >> c when wavelength λ is long, extreme phase velocities are then limited in their causal effects by the particle uncertainty σ, i.e. to vgt ± σ/ω, where ω is 展开更多
Dispersion dynamics applies wave-particle duality, together with Maxwell’s electromagnetism, and with quantization E = hν = ħω (symbol definitions in footnote) and p = h/λ = ħk, to special relativity E<sup>2...Dispersion dynamics applies wave-particle duality, together with Maxwell’s electromagnetism, and with quantization E = hν = ħω (symbol definitions in footnote) and p = h/λ = ħk, to special relativity E<sup>2</sup> = p<sup>2</sup>c<sup>2</sup> + m<sup>2</sup>c<sup>4</sup>. Calculations on a wave-packet, that is symmetric about the normal distribution, are partly conservative and partly responsive. The complex electron wave function is chiefly modelled on the real wave function of an electromagnetic photon;while the former concept of a “point particle” is downgraded to mathematical abstraction. The computations yield conclusions for phase and group velocities, v<sub>p</sub>⋅v<sub>g</sub> = c<sup>2</sup> with v<sub>p</sub> ≥ c because v<sub>g</sub> ≤ c, as in relativity. The condition on the phase velocity is most noticeable when p≪mc. Further consequences in dispersion dynamics are: derivations for ν and λ that are consistently established by one hundred years of experience in electron microscopy and particle accelerators. Values for v<sub>p</sub> = νλ = ω/k are therefore systematically verified by the products of known multiplicands or divisions by known divisors, even if v<sub>p</sub> is not independently measured. These consequences are significant in reduction of the wave-packet by resonant response during interactions between photons and electrons, for example, or between particles and particles. Thus the logic of mathematical quantum mechanics is distinguished from experiential physics that is continuous in time, and consistent with uncertainty principles. [Footnote: symbol E = energy;h = Planck’s constant;ν = frequency;ω = angular momentum;p = momentum;λ = wavelength;k = wave vector;c = speed of light;m = particle rest mass;v<sub>p</sub> = phase velocity;v<sub>g</sub> = group velocity].展开更多
From a combination of Maxwell’s electromagnetism with Planck’s law and the de Broglie hypothesis, we arrive at quantized photonic wave groups whose constant phase velocity is equal to the speed of light c = ω/k and...From a combination of Maxwell’s electromagnetism with Planck’s law and the de Broglie hypothesis, we arrive at quantized photonic wave groups whose constant phase velocity is equal to the speed of light c = ω/k and to their group velocity dω/dk. When we include special relativity expressed in simplest units, we find that, for particulate matter, the square of rest mass , i.e., angular frequency squared minus wave vector squared. This equation separates into a conservative part and a uniform responsive part. A wave function is derived in manifold rank 4, and from it are derived uncertainties and internal motion. The function solves four anomalies in quantum physics: the point particle with prescribed uncertainties;spooky action at a distance;time dependence that is consistent with the uncertainties;and resonant reduction of the wave packet by localization during measurement. A comparison between contradictory mathematical and physical theories leads to similar empirical conclusions because probability amplitudes express hidden variables. The comparison supplies orthodox postulates that are compared to physical principles that formalize the difference. The method is verified by dual harmonics found in quantized quasi-Bloch waves, where the quantum is physical;not axiomatic.展开更多
The initial purpose is to add two physical origins for the outstandingly clear mathematical description that Dirac has left in his Principles of Quantum Mechanics. The first is the “internal motion” in the wave func...The initial purpose is to add two physical origins for the outstandingly clear mathematical description that Dirac has left in his Principles of Quantum Mechanics. The first is the “internal motion” in the wave function of the electron that is now expressed through dispersion dynamics;the second is the physical origin for mathematical quantization. Bohr’s model for the hydrogen atom was “the greatest single step in the development of the theory of atomic structure.” It leads to the Schrodinger equation which is non-relativistic, but which conveniently equates together momentum and electrostatic potential in a representation containing mixed powers. Firstly, we show how the equation is expansible to approximate relativistic form by applying solutions for the dilation of time in special relativity, and for the contraction of space. The adaptation is to invariant “harmonic events” that are digitally quantized. Secondly, the internal motion of the electron is described by a stable wave packet that implies wave-particle duality. The duality includes uncertainty that is precisely described with some variance from Heisenberg’s axiomatic limit. Harmonic orbital wave functions are self-constructive. This is the physical origin of quantization.展开更多
Effect of laser fields on Na2 interaction potentials is studied by calculating the time-resolved photoelectron spectrum （TRPES） with the time-dependent wave-packet method. It is shown that the photoelectron spectrum...Effect of laser fields on Na2 interaction potentials is studied by calculating the time-resolved photoelectron spectrum （TRPES） with the time-dependent wave-packet method. It is shown that the photoelectron spectrum at different delay times reflects the population in different electronic states. We inspect the periodicity of vibrational motion in neutral states, and map the vibrational wave-packet propagation in corresponding internuclear coordinate.展开更多
Two problems in solid state physics and superconductivity are addressed by applications of dispersion dynamics. The first is the Hall effect. The dynamics of charges that yield positive Hall coefficients in material h...Two problems in solid state physics and superconductivity are addressed by applications of dispersion dynamics. The first is the Hall effect. The dynamics of charges that yield positive Hall coefficients in material having no mobile positive charges have always been problematic The effect requires both electric and magnetic response, but magnetic deflection is only possible in mobile charges. In high temperature superconductors, these charges must be electrons. Contrary to Newton’s second law, their acceleration is reversed in crystal fields that dictate negative dispersion. This is evident in room temperature measurements, but a second problem arises in supercurrents at low temperatures. The charge dynamics in material having zero internal electric field because of zero resistivity;and zero magnetic field because of the Meissner-Ochsenfeld diamagnetism;while the supercurrents themselves have properties of zero net momentum;zero spin;and sometimes, zero charge;are so far from having been resolved that they may never have been addressed. Again, dispersion dynamics are developed to provide solutions given by reduction of the superconducting wave packet. The reduction is here physically analyzed, though it is usually treated as a quantized unobservable.展开更多
The dynamics of the double-channel dissociation of the NaCs molecule is investigated by using the time-dependent wave packet （TDWP） method with the ＂split operator-Fourier transform＂ scheme. At a given wavelength ...The dynamics of the double-channel dissociation of the NaCs molecule is investigated by using the time-dependent wave packet （TDWP） method with the ＂split operator-Fourier transform＂ scheme. At a given wavelength and intensity of laser pulse, the population of each state changing with time is obtained. The photo-absorption spectra and kinetic- energy distribution of the dissociation fragments, which exhibit vibration-level structure and dispersion of the wave packet, respectively, are also obtained. The results show that by increasing the laser intensity, one can find not only the band center shift of the photo-absorption spectrum, but also the change of the fragment energy. The appearance of the diffusive band in the photo-absorption spectrum and the multiple peaks in the kinetic-energy spectrum can be attributed to the effects of the predissoeiation limit and the external field.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10374012 and 10674022.
文摘The Autler-Townes （AT） splitting in femtosecond photoelectron spectrum of three-level Li2 molecules is theoretically investigated using time-dependent quantum wave packet method. With proper femtosecond laser pulses, three peaks of the AT splitting can be observed in the photoelectron spectrum. The AT splitting stems from rapid Rabi oscillation caused by intense ultrashort laser pluses. The effects of laser parameters on the molecular ionization dynamics are also discussed.
基金Supported by the National Natural Science Foundation of China under Grant No 10374012.
文摘The effect of pulse temporal profiles on the Autler-Townes （AT） splitting in photoelectron spectra is theoretically studied by employing the time-dependent wave packet method for a rotational Na2 molecule. The AT splitting which results from the sufficient Rabi oscillations is affected by the pulse profile and molecular alignment. The AT splitting may be observed only by utilizing proper pulse profiles with a certain intensity.
基金Financial support from Higher Education Commission(HEC)of Pakistan,under Grant No.20-14808/NRPU/R&D/HEC/20212021
文摘Position-dependent-mass systems are of great importance in many physical situations,such as the transport of charge carriers in semiconductors with non-uniform composition and in the theory of many-body interactions in condensed matter.Here we investigate,numerically and analytically,the phenomenon of fractional revivals in such systems,which is a generic characteristic manifested by the wave-packet evolution in bounded Hamiltonian systems.Identifying the fractional revivals using specific probes is an important task in the theory of quantum measurement and sensing.We numerically simulate the temporal evolution of probability density and information entropy density,which manifest self-similarly recurring interference patterns,namely,quantum carpets.Our numerical results show that the quantum carpets not only serve as an effective probe for recognizing the fractional revivals of various order but they efficiently describe the effect of spatially-varying mass on the structure of fractional revivals,which is manifested as a symmetry breaking in their designs.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0301803 and 2016YFA0302800)the National Natural Science Foundation of China(Grant Nos.11604103,11704132,11822403,and 91636218),the NSAF,China(Grant Nos.U1801661 and U1830111)+4 种基金the PCSIRT,China(Grant No.IRT1243)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2016A030313436,2018A030313322,and 2018A0303130066)the KPST of Guangzhou(Grant No.201804020055)China Postdoctoral Science Foundation(Grant No.2018M633063)the Startup Foundation of SCNU.
文摘We analytically and numerically investigate the dynamical properties of the tilted dispersion relativistic quasiparticles emerged in a cold atomic optical lattice system.By introducing the next nearest neighboring(NNN)hopping term into Su-Schrieffer-Heeger(SSH)model,the Dirac quasiparticles with tilted dispersion relation are realized.The results show that the tilted dispersion causes a drift in relativistic quasiparticles rather than affecting interference behavior between inner states.To be specific,the relativistic phenomena of the quasiparticles induced by the inner state interference(such as Zitterbewegung,Klein paradox,etc.)is completely unaffected by the tilted dispersion.In order to distinguish the drift induced by tilted dispersion and common initial velocity,we calculate the momentum distribution of the relativistic quasiparticles.We obtain the difference between the drift induced by initial velocity and tilted dispersion.The former affects the ZB,while the latter does not.By using this character,we propose a quench dynamics scheme to obtain a stable mono-spin state.The proposed cold atomic lattice system would provide a promising platform in exploring the intrinsic exotic physics of relativistic quasiparticles and the related systems.
文摘In the special theory of relativity, massive particles can travel at neither the speed of light c nor faster. Meanwhile, since the photon was quantized, many have thought of it as a point particle. How pointed? The idea could be a mathematical device or physical simplification. By contrast, the preceding notion of wave-group duality has two velocities: a group velocity vg and a phase velocity vp. In light vp = vg = c;but it follows from special relativity that, in massive particles, vp > c. The phase velocity is the product of the two best measured variables, and so their product constitutes internal motion that travels, verifiably, faster than light. How does vp then appear in Minkowski space? For light, the spatio-temporal Lorentz invariant metric is s2=c2t2−x2−y2−z2, the same in whatever frame it is viewed. The space is divided into 3 parts: firstly a cone, symmetric about the vertical axis ct > 0 that represents the world line of a stationary particle while the conical surface at s = 0 represents the locus for light rays that travel at the speed of light c. Since no real thing travels faster than the speed of light c, the surface is also a horizon for what can be seen by an observer starting from the origin at time t = 0. Secondly, an inverted cone represents, equivalently, time past. Thirdly, outside the cones, inaccessible space. The phase velocity vp, group velocity vg and speed of light are all equal in free space, vp = vg = c, constant. By contrast, for particles, where causality is due to particle interactions having rest mass mo > 0, we have to employ the Klein-Gordon equation with s2=c2t2−x2−y2−z2+mo2c2. Now special relativity requires a complication: vp.vg = c2 where vg c and therefore vp > c. In the volume outside the cones, causality due to light interactions cannot extend beyond the cones. However, since vp > c and even vp >> c when wavelength λ is long, extreme phase velocities are then limited in their causal effects by the particle uncertainty σ, i.e. to vgt ± σ/ω, where ω is
文摘Dispersion dynamics applies wave-particle duality, together with Maxwell’s electromagnetism, and with quantization E = hν = ħω (symbol definitions in footnote) and p = h/λ = ħk, to special relativity E<sup>2</sup> = p<sup>2</sup>c<sup>2</sup> + m<sup>2</sup>c<sup>4</sup>. Calculations on a wave-packet, that is symmetric about the normal distribution, are partly conservative and partly responsive. The complex electron wave function is chiefly modelled on the real wave function of an electromagnetic photon;while the former concept of a “point particle” is downgraded to mathematical abstraction. The computations yield conclusions for phase and group velocities, v<sub>p</sub>⋅v<sub>g</sub> = c<sup>2</sup> with v<sub>p</sub> ≥ c because v<sub>g</sub> ≤ c, as in relativity. The condition on the phase velocity is most noticeable when p≪mc. Further consequences in dispersion dynamics are: derivations for ν and λ that are consistently established by one hundred years of experience in electron microscopy and particle accelerators. Values for v<sub>p</sub> = νλ = ω/k are therefore systematically verified by the products of known multiplicands or divisions by known divisors, even if v<sub>p</sub> is not independently measured. These consequences are significant in reduction of the wave-packet by resonant response during interactions between photons and electrons, for example, or between particles and particles. Thus the logic of mathematical quantum mechanics is distinguished from experiential physics that is continuous in time, and consistent with uncertainty principles. [Footnote: symbol E = energy;h = Planck’s constant;ν = frequency;ω = angular momentum;p = momentum;λ = wavelength;k = wave vector;c = speed of light;m = particle rest mass;v<sub>p</sub> = phase velocity;v<sub>g</sub> = group velocity].
文摘From a combination of Maxwell’s electromagnetism with Planck’s law and the de Broglie hypothesis, we arrive at quantized photonic wave groups whose constant phase velocity is equal to the speed of light c = ω/k and to their group velocity dω/dk. When we include special relativity expressed in simplest units, we find that, for particulate matter, the square of rest mass , i.e., angular frequency squared minus wave vector squared. This equation separates into a conservative part and a uniform responsive part. A wave function is derived in manifold rank 4, and from it are derived uncertainties and internal motion. The function solves four anomalies in quantum physics: the point particle with prescribed uncertainties;spooky action at a distance;time dependence that is consistent with the uncertainties;and resonant reduction of the wave packet by localization during measurement. A comparison between contradictory mathematical and physical theories leads to similar empirical conclusions because probability amplitudes express hidden variables. The comparison supplies orthodox postulates that are compared to physical principles that formalize the difference. The method is verified by dual harmonics found in quantized quasi-Bloch waves, where the quantum is physical;not axiomatic.
文摘The initial purpose is to add two physical origins for the outstandingly clear mathematical description that Dirac has left in his Principles of Quantum Mechanics. The first is the “internal motion” in the wave function of the electron that is now expressed through dispersion dynamics;the second is the physical origin for mathematical quantization. Bohr’s model for the hydrogen atom was “the greatest single step in the development of the theory of atomic structure.” It leads to the Schrodinger equation which is non-relativistic, but which conveniently equates together momentum and electrostatic potential in a representation containing mixed powers. Firstly, we show how the equation is expansible to approximate relativistic form by applying solutions for the dilation of time in special relativity, and for the contraction of space. The adaptation is to invariant “harmonic events” that are digitally quantized. Secondly, the internal motion of the electron is described by a stable wave packet that implies wave-particle duality. The duality includes uncertainty that is precisely described with some variance from Heisenberg’s axiomatic limit. Harmonic orbital wave functions are self-constructive. This is the physical origin of quantization.
基金Supported by the National Natural Science Foundation of China under Grant No 10575017.
文摘Effect of laser fields on Na2 interaction potentials is studied by calculating the time-resolved photoelectron spectrum （TRPES） with the time-dependent wave-packet method. It is shown that the photoelectron spectrum at different delay times reflects the population in different electronic states. We inspect the periodicity of vibrational motion in neutral states, and map the vibrational wave-packet propagation in corresponding internuclear coordinate.
文摘Two problems in solid state physics and superconductivity are addressed by applications of dispersion dynamics. The first is the Hall effect. The dynamics of charges that yield positive Hall coefficients in material having no mobile positive charges have always been problematic The effect requires both electric and magnetic response, but magnetic deflection is only possible in mobile charges. In high temperature superconductors, these charges must be electrons. Contrary to Newton’s second law, their acceleration is reversed in crystal fields that dictate negative dispersion. This is evident in room temperature measurements, but a second problem arises in supercurrents at low temperatures. The charge dynamics in material having zero internal electric field because of zero resistivity;and zero magnetic field because of the Meissner-Ochsenfeld diamagnetism;while the supercurrents themselves have properties of zero net momentum;zero spin;and sometimes, zero charge;are so far from having been resolved that they may never have been addressed. Again, dispersion dynamics are developed to provide solutions given by reduction of the superconducting wave packet. The reduction is here physically analyzed, though it is usually treated as a quantized unobservable.
基金Project supported by the National Natural Science Foundation of China(Grant No.11074151)the Doctoral Program Foundation of Institutions of Higher Education of China(Grant No.20123704110002)
文摘The dynamics of the double-channel dissociation of the NaCs molecule is investigated by using the time-dependent wave packet （TDWP） method with the ＂split operator-Fourier transform＂ scheme. At a given wavelength and intensity of laser pulse, the population of each state changing with time is obtained. The photo-absorption spectra and kinetic- energy distribution of the dissociation fragments, which exhibit vibration-level structure and dispersion of the wave packet, respectively, are also obtained. The results show that by increasing the laser intensity, one can find not only the band center shift of the photo-absorption spectrum, but also the change of the fragment energy. The appearance of the diffusive band in the photo-absorption spectrum and the multiple peaks in the kinetic-energy spectrum can be attributed to the effects of the predissoeiation limit and the external field.
