Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single...Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single photon wave packet with a definite total angular momentum(TAM).The entangled pair produced in this process possesses well-defined mean TAM with the TAM variation being much smaller than h.On top of that,the variation exponentially decreases with the increase in TAM of the incident photon.Our model allows one to track the time evolution of the state of the entangled pair.An experimentally feasible scenario is assumed,in which the incident photon interacts with a spatially confined atomic target.We conclude that induced emission can be used as a source of entangled vortex photons with applications in atomic physics experiments,quantum optics,and quantum information sciences.展开更多
We theoretically investigate the effects of different electronic states as the initial state on the vortex patterns in photoelectron momentum distributions(PMDs)from numerical solutions of the two-dimensional(2D)time-...We theoretically investigate the effects of different electronic states as the initial state on the vortex patterns in photoelectron momentum distributions(PMDs)from numerical solutions of the two-dimensional(2D)time-dependent Schrodinger equation(TDSE)of He^(+)with a pair of counter-rotating circularly polarized attosecond pulses.It is found that the number of spiral arms in vortex patterns is equal to the number of the absorbed photons when the initial state is the ground state.However,the number of spiral arms in vortex patterns is always two more than the number of the absorbed photons when the initial state is the excited state.This sensitivity is attributed to the initial electron density distribution.In addition,we have demonstrated the PMDs for different initial electronic states with the same wavelengths and analyzed their corresponding physical mechanisms.It is illustrated that the method presented can be employed to effectively control the distribution of the electron vortices.展开更多
A series of cross-sectional flow fields of Counterrotating Vortex Pairs(CVPs) generated by a large-scale ramp vortex generator is observed using an ice-cluster-based Planar Laser Scattering(PLS) method in a shock tunn...A series of cross-sectional flow fields of Counterrotating Vortex Pairs(CVPs) generated by a large-scale ramp vortex generator is observed using an ice-cluster-based Planar Laser Scattering(PLS) method in a shock tunnel with a nominal flow Mach number of 6. Combined with a numerical simulation, two streamwise CVPs with opposite rotating directions are identified in the wake flow of the vortex generator with an absence of a boundary layer, namely, a Primary CVP(PCVP) and a Secondary CVP(SCVP). The wake flow is divided into two stages with different features of the PCVP and SCVP. In Stage Ⅰ, the PCVP and SCVP gradually mature, and the flow is relatively stable. In Stage Ⅱ, the PCVP and SCVP depart from each other, and the flow becomes unstable. The profiles of the transverse velocity in the spanwise symmetry plane induced by the PCVP and SCVP do not obey the scaling law of CVPs immersed in the boundary layer. A new scaling law is proposed, in which the transverse distances between adjacent saddle points in the cross-sectional flow field are used as the characteristic lengths for the PCVP and SCVP. After this new scaling procedure, the profiles of transverse velocity induced by the PCVP and SCVP at different streamwise locations collapse well. Moreover, the PLS images show that the mixing between the CVPs and the outside high-momentum flow becomes evident at approximately 5.5 times the height of the vortex generator, which is earlier than that immersed in the boundary layer. These findings enrich the knowledge of CVPs in the hypersonic regime, especially in the absence of the boundary layer.展开更多
Three-Dimensional(3D)swirling flow structures,generated by a counter-rotating dualstage swirler in a confined chamber with a confinement ratio of 1.53,were experimentally investigated at Re=2.3×10^(5)using Tomogr...Three-Dimensional(3D)swirling flow structures,generated by a counter-rotating dualstage swirler in a confined chamber with a confinement ratio of 1.53,were experimentally investigated at Re=2.3×10^(5)using Tomographic Particle Image Velocimetry(Tomo-PIV)and planar Particle Image Velocimetry(PIV).Based on the analysis of the 3D time-averaged swirling flow structures and 3D Proper Orthogonal Decomposition(POD)of the Tomo-PIV data,typical coherent flow structures,including the Corner Recirculation Zone(CRZ),Central Recirculation Zone(CTRZ),and Lip Recirculation Zone(LRZ),were extracted.The counter-rotating dual-stage swirler with a Venturi flare generates the independence process of vortex breakdown from the main stage and pilot stage,leading to the formation of an LRZ and a smaller CTRZ near the nozzle outlet.The confinement squeezes the CRZ to the corner and causes a reverse rotation flow to limit the shape of the CTRZ.A large-scale flow structure caused by the main stage features an explosive breakup,flapping,and Precessing Vortex Core(PVC).The explosive breakup mode dominates the swirling flow structures owing to the expansion and construction of the main jet,whereas the flapping mode is related to the wake perturbation.Confinement limits the expansion of PVC and causes it to contract after the impacting area.展开更多
In this paper,the relationship between a pair of low-frequency vortexes over the equatorial Indian Ocean and the South China Sea(SCS) summer monsoon onset is studied based on a multi-year(1980-2003) analysis.A pair of...In this paper,the relationship between a pair of low-frequency vortexes over the equatorial Indian Ocean and the South China Sea(SCS) summer monsoon onset is studied based on a multi-year(1980-2003) analysis.A pair of vortexes symmetric about the equator is an important feature prior to the SCS summer monsoon onset.A composite analysis shows that the life cycle of the pair of vortexes is closely associated with the SCS summer monsoon onset.The westerly between the twin cyclones is an important factor to the SCS summer monsoon onset process.展开更多
Tight focusing properties of an azimuthally polarized Gaussian beam with a pair of vortices through a dielectric interface is theoretically investigated by vector diffraction theory. For the incident beam with a pair ...Tight focusing properties of an azimuthally polarized Gaussian beam with a pair of vortices through a dielectric interface is theoretically investigated by vector diffraction theory. For the incident beam with a pair of vortices of opposite topological charges, the vortices move toward each other, annihilate and revive in the vicinity of focal plane, which results in the generation of many novel focal patterns. The usable focal structures generated through the tight focusing of the double-vortex beams may find applications in micro-particle trapping, manipulation, and material processing, etc.展开更多
The axisymmetric vortex sheet model developed by Nitsche and Krasny had been extended to study the formation of vortex rings (pairs) at the edge of circular (2D) tube and opening. Computations based on this model wer...The axisymmetric vortex sheet model developed by Nitsche and Krasny had been extended to study the formation of vortex rings (pairs) at the edge of circular (2D) tube and opening. Computations based on this model were in good agreement with the experiments (Didden (1979) for circular tube and Auerbach (1987) for 2D tube and opening). Using this new model, evidences are provided to show that the main failure of the similarity theory (the false prediction of axial trajectory of vortex ring) is due to its ignorance of the self-induced ring velocity (mutual induction for vortex pair). The Glezer (1988)'s summary on the influence of piston speed upon the shedding circulation was also discussed, and finally the variation of core distribution of vortex ring with turning angle and piston speed was given. (Edited author abstract) 22 Refs.展开更多
In the framework of phenomenological time-dependent Ginzburg-Landau（TDGL） formalism,the dynamical properties of vortex-antivortex（V-Av） pair in a superconductor film with a narrow slit was studied.The slit positio...In the framework of phenomenological time-dependent Ginzburg-Landau（TDGL） formalism,the dynamical properties of vortex-antivortex（V-Av） pair in a superconductor film with a narrow slit was studied.The slit position and length can have a great impact not only on the vortex dynamical behavior but also the current-voltage（Ⅰ-Ⅴ） characteristics of the sample.Kinematic vortex lines can be predominated by the location of the slit.In the range of relatively low applied currents for a constant weak magnetic field,kinematic vortex line appears at right or left side of the slit by turns periodically.We found such single-side kinematic vortex line cannot lead to a jump in the Ⅰ-Ⅴ curve.At higher applied currents the phase-slip lines can be observed at left and right sides of the slit simultaneously.The competition between the vortex created at the lateral edge of the sample and the V-Av pair in the slit will result in three distinctly different scenarios of vortex dynamics depending on slit length：the lateral vortex penetrates the sample to annihilate the antivortex in the slit;the V-Av pair in the slit are driven off and expelled laterally;both the lateral vortex and the slit antivortex are depinned and driven together to annihilation in the halfway.展开更多
The method of nonlinear parabolized stability equations（PSE） is applied in the simulation of vortex structures in compressible mixing layer.The spatially-evolving unstable waves,which dominate the vortex structure,a...The method of nonlinear parabolized stability equations（PSE） is applied in the simulation of vortex structures in compressible mixing layer.The spatially-evolving unstable waves,which dominate the vortex structure,are investigated through spatial marching method.The instantaneous flow field is obtained by adding the harmonic waves to basic flow.The results show that T-S waves do not keep growing exponentially as the linear evolution,the energy transfer to high order harmonic modes,and that finally all harmonic modes get saturated due to nonlinear interaction.The mean flow distortion induced by the nonlinear interaction between the harmonic modes and their conjugate harmonic ones,makes great change of the average flow and increases the thickness of mixing layer. PSE methods can well capture the two- and three-dimensional large scale nonlinear vortex structures in mixing layers such as vortex roll-up,vortex pairing,and A vortex.展开更多
The flow field in a typical inward-turning inlet was visualized using the Planar Laser Scattering(PLS)method in a shock tunnel with a nominal Mach number of 6.The opaque inlet,which is truncated at a series of section...The flow field in a typical inward-turning inlet was visualized using the Planar Laser Scattering(PLS)method in a shock tunnel with a nominal Mach number of 6.The opaque inlet,which is truncated at a series of sections,and the following transparent isolator,are combined to enable the optical access at different streamwise locations.The sequential PLS images provide a tomography-like flow visualization,which confirm the existence of streamwise Counter-rotating Vortex Pairs(CVPs)in both external and internal flow field of the inlet.Generation mechanisms of these CVPs are unraveled with the help of a numerical simulation,among which the cowl notch plays an important role in the generation of surface trailing CVPs along the centerline of the cowl.Moreover,the cowl shock sweeps the internal boundary layer towards the body side,which ultimately accumulates low-momentum flow on the body side in forms of a large CVP propagating downstream through the isolator.The CVPs formed in the shape-transition are responsible for the nonuniform flow field of the inward-turning inlet.This study indicates that the V-shaped cowl notch affects the downstream flow significantly and,therefore,should be examined thoroughly in practical applications.展开更多
基金The derivation of the population coefficients in the emission induced by a plane wave are supported by the Foundation for the Advancement of Theoretical Physics and Mathematics“BASIS”The extension of these calculations to an incident vortex photon is supported by the Ministry of Science and Higher Education of the Russian Federation(Grant No.FSER-2025-0012)+2 种基金The studies of time dynamics of OAM of the entangled pair are supported by the Russian Science Foundation(Grant No.23-62-10026https://rscf.ru/en/project/23-6210026/)The studies of influence of the finite localization region of an atom on its interaction with an incident vortex photons are supported by the Russian Science Foundation(Grant No.25-71-00060)。
文摘Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography.We investigate the possibility of generating such states via two-level atom emission induced by a single photon wave packet with a definite total angular momentum(TAM).The entangled pair produced in this process possesses well-defined mean TAM with the TAM variation being much smaller than h.On top of that,the variation exponentially decreases with the increase in TAM of the incident photon.Our model allows one to track the time evolution of the state of the entangled pair.An experimentally feasible scenario is assumed,in which the incident photon interacts with a spatially confined atomic target.We conclude that induced emission can be used as a source of entangled vortex photons with applications in atomic physics experiments,quantum optics,and quantum information sciences.
基金Project supported by the National Natural Science Foundation of China(Grant No.12074142)the Natural Science Foundation of Jilin Province of China(Grant No.20180101225JC)the Graduate Innovation Fund of Jilin University,China(Grant No.101832020CX337)。
文摘We theoretically investigate the effects of different electronic states as the initial state on the vortex patterns in photoelectron momentum distributions(PMDs)from numerical solutions of the two-dimensional(2D)time-dependent Schrodinger equation(TDSE)of He^(+)with a pair of counter-rotating circularly polarized attosecond pulses.It is found that the number of spiral arms in vortex patterns is equal to the number of the absorbed photons when the initial state is the ground state.However,the number of spiral arms in vortex patterns is always two more than the number of the absorbed photons when the initial state is the excited state.This sensitivity is attributed to the initial electron density distribution.In addition,we have demonstrated the PMDs for different initial electronic states with the same wavelengths and analyzed their corresponding physical mechanisms.It is illustrated that the method presented can be employed to effectively control the distribution of the electron vortices.
基金supported by the National Natural Science Foundation of China(Nos.11772325,11621202).
文摘A series of cross-sectional flow fields of Counterrotating Vortex Pairs(CVPs) generated by a large-scale ramp vortex generator is observed using an ice-cluster-based Planar Laser Scattering(PLS) method in a shock tunnel with a nominal flow Mach number of 6. Combined with a numerical simulation, two streamwise CVPs with opposite rotating directions are identified in the wake flow of the vortex generator with an absence of a boundary layer, namely, a Primary CVP(PCVP) and a Secondary CVP(SCVP). The wake flow is divided into two stages with different features of the PCVP and SCVP. In Stage Ⅰ, the PCVP and SCVP gradually mature, and the flow is relatively stable. In Stage Ⅱ, the PCVP and SCVP depart from each other, and the flow becomes unstable. The profiles of the transverse velocity in the spanwise symmetry plane induced by the PCVP and SCVP do not obey the scaling law of CVPs immersed in the boundary layer. A new scaling law is proposed, in which the transverse distances between adjacent saddle points in the cross-sectional flow field are used as the characteristic lengths for the PCVP and SCVP. After this new scaling procedure, the profiles of transverse velocity induced by the PCVP and SCVP at different streamwise locations collapse well. Moreover, the PLS images show that the mixing between the CVPs and the outside high-momentum flow becomes evident at approximately 5.5 times the height of the vortex generator, which is earlier than that immersed in the boundary layer. These findings enrich the knowledge of CVPs in the hypersonic regime, especially in the absence of the boundary layer.
基金supported by the National Natural Science Foundation of China(Nos.12232002,12072017,12002199,and 11721202)。
文摘Three-Dimensional(3D)swirling flow structures,generated by a counter-rotating dualstage swirler in a confined chamber with a confinement ratio of 1.53,were experimentally investigated at Re=2.3×10^(5)using Tomographic Particle Image Velocimetry(Tomo-PIV)and planar Particle Image Velocimetry(PIV).Based on the analysis of the 3D time-averaged swirling flow structures and 3D Proper Orthogonal Decomposition(POD)of the Tomo-PIV data,typical coherent flow structures,including the Corner Recirculation Zone(CRZ),Central Recirculation Zone(CTRZ),and Lip Recirculation Zone(LRZ),were extracted.The counter-rotating dual-stage swirler with a Venturi flare generates the independence process of vortex breakdown from the main stage and pilot stage,leading to the formation of an LRZ and a smaller CTRZ near the nozzle outlet.The confinement squeezes the CRZ to the corner and causes a reverse rotation flow to limit the shape of the CTRZ.A large-scale flow structure caused by the main stage features an explosive breakup,flapping,and Precessing Vortex Core(PVC).The explosive breakup mode dominates the swirling flow structures owing to the expansion and construction of the main jet,whereas the flapping mode is related to the wake perturbation.Confinement limits the expansion of PVC and causes it to contract after the impacting area.
基金financed by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No. KZCX2-YW-Q11-03)the National Basic Research Program of China(Grant No.2010CB950401)
文摘In this paper,the relationship between a pair of low-frequency vortexes over the equatorial Indian Ocean and the South China Sea(SCS) summer monsoon onset is studied based on a multi-year(1980-2003) analysis.A pair of vortexes symmetric about the equator is an important feature prior to the SCS summer monsoon onset.A composite analysis shows that the life cycle of the pair of vortexes is closely associated with the SCS summer monsoon onset.The westerly between the twin cyclones is an important factor to the SCS summer monsoon onset process.
文摘Tight focusing properties of an azimuthally polarized Gaussian beam with a pair of vortices through a dielectric interface is theoretically investigated by vector diffraction theory. For the incident beam with a pair of vortices of opposite topological charges, the vortices move toward each other, annihilate and revive in the vicinity of focal plane, which results in the generation of many novel focal patterns. The usable focal structures generated through the tight focusing of the double-vortex beams may find applications in micro-particle trapping, manipulation, and material processing, etc.
基金The project is supported by National Natural Science Foundation of China and Doctoral Program of Institution of Higher Education
文摘The axisymmetric vortex sheet model developed by Nitsche and Krasny had been extended to study the formation of vortex rings (pairs) at the edge of circular (2D) tube and opening. Computations based on this model were in good agreement with the experiments (Didden (1979) for circular tube and Auerbach (1987) for 2D tube and opening). Using this new model, evidences are provided to show that the main failure of the similarity theory (the false prediction of axial trajectory of vortex ring) is due to its ignorance of the self-induced ring velocity (mutual induction for vortex pair). The Glezer (1988)'s summary on the influence of piston speed upon the shedding circulation was also discussed, and finally the variation of core distribution of vortex ring with turning angle and piston speed was given. (Edited author abstract) 22 Refs.
基金Project supported by the Fundamental Research Funds for the Central Universities,China(Grant Nos.310812171011 and G2016KY0305)the National Natural Science Foundation of China(Grant No.11421062)the National Key Project of Magneto-Constrained Fusion Energy Development Program,China(Grant No.2013GB110002)
文摘In the framework of phenomenological time-dependent Ginzburg-Landau（TDGL） formalism,the dynamical properties of vortex-antivortex（V-Av） pair in a superconductor film with a narrow slit was studied.The slit position and length can have a great impact not only on the vortex dynamical behavior but also the current-voltage（Ⅰ-Ⅴ） characteristics of the sample.Kinematic vortex lines can be predominated by the location of the slit.In the range of relatively low applied currents for a constant weak magnetic field,kinematic vortex line appears at right or left side of the slit by turns periodically.We found such single-side kinematic vortex line cannot lead to a jump in the Ⅰ-Ⅴ curve.At higher applied currents the phase-slip lines can be observed at left and right sides of the slit simultaneously.The competition between the vortex created at the lateral edge of the sample and the V-Av pair in the slit will result in three distinctly different scenarios of vortex dynamics depending on slit length：the lateral vortex penetrates the sample to annihilate the antivortex in the slit;the V-Av pair in the slit are driven off and expelled laterally;both the lateral vortex and the slit antivortex are depinned and driven together to annihilation in the halfway.
基金supported by the National Natural Sci- ence Foundation of China(11102198)
文摘The method of nonlinear parabolized stability equations（PSE） is applied in the simulation of vortex structures in compressible mixing layer.The spatially-evolving unstable waves,which dominate the vortex structure,are investigated through spatial marching method.The instantaneous flow field is obtained by adding the harmonic waves to basic flow.The results show that T-S waves do not keep growing exponentially as the linear evolution,the energy transfer to high order harmonic modes,and that finally all harmonic modes get saturated due to nonlinear interaction.The mean flow distortion induced by the nonlinear interaction between the harmonic modes and their conjugate harmonic ones,makes great change of the average flow and increases the thickness of mixing layer. PSE methods can well capture the two- and three-dimensional large scale nonlinear vortex structures in mixing layers such as vortex roll-up,vortex pairing,and A vortex.
基金supported by the National Natural Science Foundation of China(Nos.11772325,11872356 and 11621202)。
文摘The flow field in a typical inward-turning inlet was visualized using the Planar Laser Scattering(PLS)method in a shock tunnel with a nominal Mach number of 6.The opaque inlet,which is truncated at a series of sections,and the following transparent isolator,are combined to enable the optical access at different streamwise locations.The sequential PLS images provide a tomography-like flow visualization,which confirm the existence of streamwise Counter-rotating Vortex Pairs(CVPs)in both external and internal flow field of the inlet.Generation mechanisms of these CVPs are unraveled with the help of a numerical simulation,among which the cowl notch plays an important role in the generation of surface trailing CVPs along the centerline of the cowl.Moreover,the cowl shock sweeps the internal boundary layer towards the body side,which ultimately accumulates low-momentum flow on the body side in forms of a large CVP propagating downstream through the isolator.The CVPs formed in the shape-transition are responsible for the nonuniform flow field of the inward-turning inlet.This study indicates that the V-shaped cowl notch affects the downstream flow significantly and,therefore,should be examined thoroughly in practical applications.
