We investigate the vortex structures excited by Ioffe-Pritchard magnetic field and Dresselhaus-type spin-orbit coupling in F=2 ferromagnetic Bose-Einstein condensates.In the weakly interatomic interacting regime,an ex...We investigate the vortex structures excited by Ioffe-Pritchard magnetic field and Dresselhaus-type spin-orbit coupling in F=2 ferromagnetic Bose-Einstein condensates.In the weakly interatomic interacting regime,an external magnetic field can generate a polar-core vortex in which the canonical particle current is zero.With the combined effect of spin-orbit coupling and magnetic field,the ground state experiences a transition from polar-core vortex to Mermin-Ho vortex,in which the canonical particle current is anticlockwise.For fixed spin-orbit coupling strengths,the evolution of phase winding,magnetization,and degree of phase separation with magnetic field are studied.Additionally,with further increasing spin-orbit coupling strength,the condensate exhibits symmetrical density domains separated by radial vortex arrays.Our work paves the way to explore exotic topological excitations in high-spin systems.展开更多
We investigate the anisotropic spin-orbit coupled spin-2 Bose-Einstein condensates with Ioffe-Pritchard magnetic field.With nonzero magnetic field,anisotropic spin-orbit coupling will introduce several vortices and fu...We investigate the anisotropic spin-orbit coupled spin-2 Bose-Einstein condensates with Ioffe-Pritchard magnetic field.With nonzero magnetic field,anisotropic spin-orbit coupling will introduce several vortices and further generate a vortex chain.Inside the vortex chain,the vortices connect to each other,forming a line along the axis.The physical nature of the vortex chain can be explained by the particle current and the momentum distribution.The vortex number inside the vortex chain can be influenced via varying the magnetic field.Through adjusting the anisotropy of the spin-orbit coupling,the direction of the vortex chain is changed,and the vortex lattice can be triggered.Moreover,accompanied by the variation of the atomic interactions,the density and the momentum distribution of the vortex chain are affected.The realization and the detection of the vortex chain are compatible with current experimental techniques.展开更多
We experimentally produce the rubidium Bose-Einstein condensate in an optically plugged magnetic quadrupole trap. A far blue-detuned focused laser beam with a wavelength of 532nm is plugged in the center of the magnet...We experimentally produce the rubidium Bose-Einstein condensate in an optically plugged magnetic quadrupole trap. A far blue-detuned focused laser beam with a wavelength of 532nm is plugged in the center of the magnetic quadrupole trap to increase the number of trapped atoms and to suppress the heating. An rf evaporative cooling in the magneto-optical hybrid trap is applied to decrease the atom temperature into degeneracy. The atom number of the condensate is 1.2（0.4）× 10^5 and the temperature is below lOOnK. We also study characteristic behaviors of the condensate, such as phase space density, condensate fraction and anisotropic expansion.展开更多
We report on the production of large sodium Bose^Einstein condensates in a hybrid of magnetic quadrupole and optical dipole trap. With an optimized spin-flip Zeeman slower, 2 ~ 1010 sodium atoms are captured in the ma...We report on the production of large sodium Bose^Einstein condensates in a hybrid of magnetic quadrupole and optical dipole trap. With an optimized spin-flip Zeeman slower, 2 ~ 1010 sodium atoms are captured in the magneto-optical trap （MOT）. A long distance magnetic transfer setup moves the cold atom over 46cm from the MOT chamber to the UHV science chamber, which provides great optical access and long conservative trap lifetime. After evaporative cooling in the hybrid trap, we produce nearly pure condensates of 1 ~ 107 atoms with lifetime of 80 s in the optical dipole trap.展开更多
For a Bose-Einstein condensate （BEC） confined in a double lattice consisting of two weak laser standing waves we find the Melnikov chaotic solution and chaotic region of parameter space by using the direct perturbat...For a Bose-Einstein condensate （BEC） confined in a double lattice consisting of two weak laser standing waves we find the Melnikov chaotic solution and chaotic region of parameter space by using the direct perturbation method. In the chaotic region, spatial evolutions of the chaotic solution and the corresponding distribution of particle number density are bounded but unpredictable between their superior and inferior limits. It is illustrated that when the relation k1≈ k2 between the two laser wave vectors is kept, the adjustment from k2 〈 k1 to k2 ≥ k1 can transform the chaotic region into regular one or the other way round. This suggests a feasible scheme for generating and controlling chaos, which could lead to an experimental observation in the near future.展开更多
Based on the experimental device which is a non-uniform magnetic field to trap an atom, we show how to obtain a certain velocity of a Bose gas by controlling the magnetic coils. By comparing the relationship of the di...Based on the experimental device which is a non-uniform magnetic field to trap an atom, we show how to obtain a certain velocity of a Bose gas by controlling the magnetic coils. By comparing the relationship of the different current supply and delay time versus the ultimate velocity of the atom, we theoretically predict the method of accelerating the gases to an expected velocity. This method is of great convenience and significance for the applications in cold atom physics and precision measurements.展开更多
An extended variation approach to describing the dynamic evolution of self-attractive Bose-Einstein condensates is developed. We consider bright matter-wave solitons in the presence of a parabolic magnetic potential a...An extended variation approach to describing the dynamic evolution of self-attractive Bose-Einstein condensates is developed. We consider bright matter-wave solitons in the presence of a parabolic magnetic potential and a timespace periodic optical lattice. The dynamics of condensates is shown to be well approximated by four coupled nonlinear differential equations. A noteworthy feature is that the extended variation approach gives a critical strength ratio to support multiple stable lattice sites for the condensate. We further examine the existence of the solitons and their stabilities at the multiple stable lattice sites. In this case, the analytical predictions of Bose-Einstein condensates variational dynamics are found to be in good agreement with numerical simulations. We then find a stable region for successful manipulating matter-wave solitons without collapse, which are dragged from an initial stationary to a prescribed position by a moving periodic optical lattice.展开更多
We investigate the thermodynamic properties of an ideal charged Bose gas confined in an anisotropic harmonic po- tential and a constant magnetic field. Using an accurate density of states, we calculate analytically th...We investigate the thermodynamic properties of an ideal charged Bose gas confined in an anisotropic harmonic po- tential and a constant magnetic field. Using an accurate density of states, we calculate analytically the thermodynamic potential and consequently various intriguing thermodynamic properties, including the Bose-Einstein transition tempera- ture, the specific heat, magnetization, and the corrections to these quantities due to the finite number of particles are also given explicitly. In contrast to the infinite number of particles scenarios, we show that those thermodynamic properties, particularly the Bose-Einstein transition temperature depends upon the strength of the magnetic field due to the finiteness of the particle numbers, and the collective effects of a finite number of particles become larger when the particle number decreases. Moreover, the magnetization varies with the temperature due to the finiteness of the particle number while it keeps invariant in the thermodynamic limit N -∞.展开更多
This paper investigates the dynamics of dark solitons in a Bose-Einstein condensate with a magnetic trap and an optical lattice （OL） trap, and analyses the effects of the periodic OL potential on the dynamics by app...This paper investigates the dynamics of dark solitons in a Bose-Einstein condensate with a magnetic trap and an optical lattice （OL） trap, and analyses the effects of the periodic OL potential on the dynamics by applying the variational approach based on the renormalized integrals of motion. The results show that the dark soliton becomes only a standing-wave and free propagation of the dark soliton is not possible when the periodic length of the OL potential is approximately equal to the effective width of the dark soliton. When the periodic length is very small or very large, the effects of the OL potential on the dark soliton will be sharply reduced. Finally, the numerical results confirm these theoretical findings.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0301500)the National Natural Science Foundation of China(Grant Nos.61835013 and 11971067)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB01020300 and XDB21030300)Beijing Natural Science Foundation,China(Grant No.1182009)Beijing Great Wall Talents Cultivation Program,China(Grant No.CIT&TCD20180325)。
文摘We investigate the vortex structures excited by Ioffe-Pritchard magnetic field and Dresselhaus-type spin-orbit coupling in F=2 ferromagnetic Bose-Einstein condensates.In the weakly interatomic interacting regime,an external magnetic field can generate a polar-core vortex in which the canonical particle current is zero.With the combined effect of spin-orbit coupling and magnetic field,the ground state experiences a transition from polar-core vortex to Mermin-Ho vortex,in which the canonical particle current is anticlockwise.For fixed spin-orbit coupling strengths,the evolution of phase winding,magnetization,and degree of phase separation with magnetic field are studied.Additionally,with further increasing spin-orbit coupling strength,the condensate exhibits symmetrical density domains separated by radial vortex arrays.Our work paves the way to explore exotic topological excitations in high-spin systems.
基金supported by the National Key R&D Program of China(Grant No.2016YFA0301500)the National Natural Science Foundation of China(Grant Nos.61835013 and11971067)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB01020300 and XDB21030300)Beijing Natural Science Foundation(Grant No.1182009)Beijing Great Wall Talents Cultivation Program(Grant No.CIT&TCD20180325)。
文摘We investigate the anisotropic spin-orbit coupled spin-2 Bose-Einstein condensates with Ioffe-Pritchard magnetic field.With nonzero magnetic field,anisotropic spin-orbit coupling will introduce several vortices and further generate a vortex chain.Inside the vortex chain,the vortices connect to each other,forming a line along the axis.The physical nature of the vortex chain can be explained by the particle current and the momentum distribution.The vortex number inside the vortex chain can be influenced via varying the magnetic field.Through adjusting the anisotropy of the spin-orbit coupling,the direction of the vortex chain is changed,and the vortex lattice can be triggered.Moreover,accompanied by the variation of the atomic interactions,the density and the momentum distribution of the vortex chain are affected.The realization and the detection of the vortex chain are compatible with current experimental techniques.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11434015,91336106 and 11004224the National Basic Research Program of China under Grant No 2011CB921601
文摘We experimentally produce the rubidium Bose-Einstein condensate in an optically plugged magnetic quadrupole trap. A far blue-detuned focused laser beam with a wavelength of 532nm is plugged in the center of the magnetic quadrupole trap to increase the number of trapped atoms and to suppress the heating. An rf evaporative cooling in the magneto-optical hybrid trap is applied to decrease the atom temperature into degeneracy. The atom number of the condensate is 1.2（0.4）× 10^5 and the temperature is below lOOnK. We also study characteristic behaviors of the condensate, such as phase space density, condensate fraction and anisotropic expansion.
基金Supported by the National Basic Research Program of China under Grant No 2013CB922002the National Natural Science Foundation of China under Grant No 11474347
文摘We report on the production of large sodium Bose^Einstein condensates in a hybrid of magnetic quadrupole and optical dipole trap. With an optimized spin-flip Zeeman slower, 2 ~ 1010 sodium atoms are captured in the magneto-optical trap （MOT）. A long distance magnetic transfer setup moves the cold atom over 46cm from the MOT chamber to the UHV science chamber, which provides great optical access and long conservative trap lifetime. After evaporative cooling in the hybrid trap, we produce nearly pure condensates of 1 ~ 107 atoms with lifetime of 80 s in the optical dipole trap.
基金Project supported by the National Natural Science Foundation of China （Grant No 10575034）, and the Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics of China （Grant No T152504）.
文摘For a Bose-Einstein condensate （BEC） confined in a double lattice consisting of two weak laser standing waves we find the Melnikov chaotic solution and chaotic region of parameter space by using the direct perturbation method. In the chaotic region, spatial evolutions of the chaotic solution and the corresponding distribution of particle number density are bounded but unpredictable between their superior and inferior limits. It is illustrated that when the relation k1≈ k2 between the two laser wave vectors is kept, the adjustment from k2 〈 k1 to k2 ≥ k1 can transform the chaotic region into regular one or the other way round. This suggests a feasible scheme for generating and controlling chaos, which could lead to an experimental observation in the near future.
基金supported by the National Basic Research Program of China(Grant No.2011CB921501)
文摘Based on the experimental device which is a non-uniform magnetic field to trap an atom, we show how to obtain a certain velocity of a Bose gas by controlling the magnetic coils. By comparing the relationship of the different current supply and delay time versus the ultimate velocity of the atom, we theoretically predict the method of accelerating the gases to an expected velocity. This method is of great convenience and significance for the applications in cold atom physics and precision measurements.
基金supported by the National Natural Science Foundation of China (Grant Nos.10672147 and 11072219)the Natural Science Foundation of Zhejiang Province,China (Grant Nos.Y605312 and Y1080959)the Foundation of Department of Education of Zhejiang Province,China (Grant No.20030704)
文摘An extended variation approach to describing the dynamic evolution of self-attractive Bose-Einstein condensates is developed. We consider bright matter-wave solitons in the presence of a parabolic magnetic potential and a timespace periodic optical lattice. The dynamics of condensates is shown to be well approximated by four coupled nonlinear differential equations. A noteworthy feature is that the extended variation approach gives a critical strength ratio to support multiple stable lattice sites for the condensate. We further examine the existence of the solitons and their stabilities at the multiple stable lattice sites. In this case, the analytical predictions of Bose-Einstein condensates variational dynamics are found to be in good agreement with numerical simulations. We then find a stable region for successful manipulating matter-wave solitons without collapse, which are dragged from an initial stationary to a prescribed position by a moving periodic optical lattice.
基金supported by the National Natural Science Foundation of China(Grant No.11375090)the K.C.Wong Magna Foundation of Ningbo University,China
文摘We investigate the thermodynamic properties of an ideal charged Bose gas confined in an anisotropic harmonic po- tential and a constant magnetic field. Using an accurate density of states, we calculate analytically the thermodynamic potential and consequently various intriguing thermodynamic properties, including the Bose-Einstein transition tempera- ture, the specific heat, magnetization, and the corrections to these quantities due to the finite number of particles are also given explicitly. In contrast to the infinite number of particles scenarios, we show that those thermodynamic properties, particularly the Bose-Einstein transition temperature depends upon the strength of the magnetic field due to the finiteness of the particle numbers, and the collective effects of a finite number of particles become larger when the particle number decreases. Moreover, the magnetization varies with the temperature due to the finiteness of the particle number while it keeps invariant in the thermodynamic limit N -∞.
基金Project supported by the Research Program of the Hong Kong Polytechnic University (Grant No A-PA2Q)the Scientific and Technological Research Program of Education Department of Hubei Province, China (Grant No Z200722001)
文摘This paper investigates the dynamics of dark solitons in a Bose-Einstein condensate with a magnetic trap and an optical lattice （OL） trap, and analyses the effects of the periodic OL potential on the dynamics by applying the variational approach based on the renormalized integrals of motion. The results show that the dark soliton becomes only a standing-wave and free propagation of the dark soliton is not possible when the periodic length of the OL potential is approximately equal to the effective width of the dark soliton. When the periodic length is very small or very large, the effects of the OL potential on the dark soliton will be sharply reduced. Finally, the numerical results confirm these theoretical findings.
