This paper solves exactly a set of fully quantized coupled equations describing the quantum dynamics of quantum spins mixing in spin-1 Bose-Einstein condensates by deriving the exact explicit analytical expressions fo...This paper solves exactly a set of fully quantized coupled equations describing the quantum dynamics of quantum spins mixing in spin-1 Bose-Einstein condensates by deriving the exact explicit analytical expressions for the evolution of creation and annihilation operators.展开更多
We numerically simulate the dynamics of a spin-2 Bose-Einstein condensate.We find that the initialphase plays an important role in the spin component oscillations.The spin mixing processes can fully cancel out due toq...We numerically simulate the dynamics of a spin-2 Bose-Einstein condensate.We find that the initialphase plays an important role in the spin component oscillations.The spin mixing processes can fully cancel out due toquantum interference when taking some initial special phase.In all the spin mixing processes,the total spin is conversed.When the initial population is mainly occupied by a component with the maximal or minimal magnetic quantum number,the oscillations of spin components cannot happen due to the total spin conversation.The presence of quadratic Zeemanenergy terms suppresses some spin mixing processes so that the oscillations of spin components are suppressed in someinitial spin configuration.However,the linear Zeeman energy terms have no effects on the spin mixing processes.展开更多
We present an overview of our recent theoretical studies on the quantum phenomena of the spin-1 Bose Einstein condensates, including the phase diagram, soliton solutions and the formation of the topological spin textu...We present an overview of our recent theoretical studies on the quantum phenomena of the spin-1 Bose Einstein condensates, including the phase diagram, soliton solutions and the formation of the topological spin textures. A brief exploration of the effects of spin-orbit coupling on the ground-state properties is given. We put forward proposals by using the transmission spectra of an optical cavity to probe the quantum ground states： the ferromagnetic and polar phases. Quasi-one-dimension solitons and ring dark solitons are studied. It is predicted that characteristics of the magnetic solitons in optical lattice can be tuned by controlling the long-range light-induced and static magnetic dipole- dipole interactions; solutions of single-component magnetic and single-, two-, three-components polar solitons are found; ring dark solitons in spin-1 condensates are predicted to live longer lifetimes than that in their scalar counterparts. In the formation of spin textures, we have considered the theoretical model of a rapidly quenched and fast rotating trapped spin-1 Bose Einstein condensate, whose dynamics can be studied by solving the stochastic projected Gross-Pitaevskii equations. Spontaneous generation of nontrivial topological defects, such as the hexagonal lattice skyrmions and square lattice of half-quantized vortices was predicted. In particular, crystallization of merons （half skyrmions） can be generated in the presence of spin-orbit coupling.展开更多
This paper studies theoretically the spin evolution of a Bose-Einstein condensate starting from a mixture of two or three groups of 52Cr （spin-3） atoms in an optical trap. The initial state is so chosen that the con...This paper studies theoretically the spin evolution of a Bose-Einstein condensate starting from a mixture of two or three groups of 52Cr （spin-3） atoms in an optical trap. The initial state is so chosen that the condensate has total magnetization zero so that the system does not distinguish up and down. It is assumed that the system is very dilute （particle number is very small）, the temperature is very low, and the frequency of the harmonic trap is large enough. In these situations, the deviation caused by the neglect of the dipole-dipole interaction and by using the single-mode approximation is reduced. A theoretical calculation beyond the mean field theory is performed and the numerical results are helpful for the evaluation of the unknown strength go.展开更多
Exact analytical solutions are good candidates for studying and explaining the dynamics of solitons in nonlinear systems.We further extend the region of existence of spin solitons in the nonlinearity coefficient space...Exact analytical solutions are good candidates for studying and explaining the dynamics of solitons in nonlinear systems.We further extend the region of existence of spin solitons in the nonlinearity coefficient space for the spin-1 Bose-Einstein condensate.Six types of spin soliton solutions can be obtained,and they exist in different regions.Stability analysis and numerical simulation results indicate that three types of spin solitons are stable against weak noise.The non-integrable properties of the model can induce shape oscillation and increase in speed after the collision between two spin solitons.These results further enrich the soliton family for non-integrable models and can provide theoretical references for experimental studies.展开更多
We study analytically the generation of maximally entangled states （MESs） formed by a two-component Bose-Einstein condensate （BEC） trapped in an adiabatically driven single potential well. Under the condition of t...We study analytically the generation of maximally entangled states （MESs） formed by a two-component Bose-Einstein condensate （BEC） trapped in an adiabatically driven single potential well. Under the condition of the linear interaction controlled by a driven field being much stronger than the effective nonlinear interaction between the components, MESs, as some particular cases of superpositions of spin coherent states （SSCS）, may emerge periodically along with not only time evolution but also the equidifferent change of the linear coupling strength at a particular time.展开更多
We consider a SU(3) spin–orbit coupled Bose–Einstein condensate confined in a harmonic plus quartic trap.The ground-state wave functions of such a system are obtained by minimizing the Gross–Pitaevskii energy funct...We consider a SU(3) spin–orbit coupled Bose–Einstein condensate confined in a harmonic plus quartic trap.The ground-state wave functions of such a system are obtained by minimizing the Gross–Pitaevskii energy functional, and the effects of the spin-dependent interaction and spin–orbit coupling are investigated in detail.For the case of ferromagnetic spin interaction, the SU(3) spin–orbit coupling induces a threefold-degenerate plane wave ground state with nontrivial spin texture.For the case of antiferromagnetic spin interaction, the system shows phase separation for weak SU(3) spin–orbit coupling, where three discrete minima with unequal weights in momentum space are selected, while hexagonal honeycomb lattice structure for strong SU(3) SOC, where three discrete minima with equal weights are selected.展开更多
We develop a research of spin currents in a^(23)Na spinor Bose–Einstein condensate(BEC)by applying a magnetic field gradient.The spin current is successfully induced by the spin-dependent force arising from the magne...We develop a research of spin currents in a^(23)Na spinor Bose–Einstein condensate(BEC)by applying a magnetic field gradient.The spin current is successfully induced by the spin-dependent force arising from the magnetic field gradient.The dynamics of the spin components under the magnetic force is investigated.The study is promising to be extended to produce a longer spin-coherence and to enhance the sensitivity of the spin-mixing interferometry in a spinor BEC.展开更多
The experimental and theoretical research of spin-orbit-coupled ultracold atomic gases has advanced and expanded rapidly in recent years. Here, we review some of the progress that either was pioneered by our own work,...The experimental and theoretical research of spin-orbit-coupled ultracold atomic gases has advanced and expanded rapidly in recent years. Here, we review some of the progress that either was pioneered by our own work, has helped to lay the foundation, or has developed new and relevant techniques. Af- ter examining the experimental accessibility of all relevant spin-orbit coupling parameters, we discuss the fundamental properties and general applications of spin-orbit-coupled Bose-Einstein condensates （BECs） over a wide range of physical situations. For the harmonically trapped case, we show that the ground state phase transition is a Dicke-type process and that spin-orbit-coupled BECs provide a unique platform to simulate and study the Dicke model and Dicke phase transitions. For a homo- geneous BEC, we discuss the collective excitations, which have been observed experimentally using Bragg spectroscopy. They feature a roton-like minimum, the softening of which provides a potential mechanism to understand the ~round state phase transition. On the other hand, if the collective dy- namics are excited by a sudden quenching of the spin-orbit coupling parameters, we show that the resulting collective dynamics can be related to the famous Zitterbewegung in the relativistic realm. Finally, we discuss the case of a BEC loaded into a periodic optical potential. Here, the spin-orbit coupling generates isolated fiat bands within the lowest Bloch bands whereas the nonlinearity of the system leads to dynamical instabilities of these Bloch waves. The experimental verification of this instability illustrates the lack of Galilean invariance in the system.展开更多
基金Project supported by Natural Science Foundation of Jiangxi, China (Grant Nos 0612006 and 2007GZW0819)the Scientific Research Foundation of Jiangxi Provincial Department of Education (Grant No [2007]191)Funds from East China Jiaotong University
文摘This paper solves exactly a set of fully quantized coupled equations describing the quantum dynamics of quantum spins mixing in spin-1 Bose-Einstein condensates by deriving the exact explicit analytical expressions for the evolution of creation and annihilation operators.
基金The project supported by National Natural Science Foundation of China under Grant Nos.10547107 and 10571091and the Teaching and Research Foundation for the Outstanding Young Faculty of Southeast University
文摘We numerically simulate the dynamics of a spin-2 Bose-Einstein condensate.We find that the initialphase plays an important role in the spin component oscillations.The spin mixing processes can fully cancel out due toquantum interference when taking some initial special phase.In all the spin mixing processes,the total spin is conversed.When the initial population is mainly occupied by a component with the maximal or minimal magnetic quantum number,the oscillations of spin components cannot happen due to the total spin conversation.The presence of quadratic Zeemanenergy terms suppresses some spin mixing processes so that the oscillations of spin components are suppressed in someinitial spin configuration.However,the linear Zeeman energy terms have no effects on the spin mixing processes.
文摘We present an overview of our recent theoretical studies on the quantum phenomena of the spin-1 Bose Einstein condensates, including the phase diagram, soliton solutions and the formation of the topological spin textures. A brief exploration of the effects of spin-orbit coupling on the ground-state properties is given. We put forward proposals by using the transmission spectra of an optical cavity to probe the quantum ground states： the ferromagnetic and polar phases. Quasi-one-dimension solitons and ring dark solitons are studied. It is predicted that characteristics of the magnetic solitons in optical lattice can be tuned by controlling the long-range light-induced and static magnetic dipole- dipole interactions; solutions of single-component magnetic and single-, two-, three-components polar solitons are found; ring dark solitons in spin-1 condensates are predicted to live longer lifetimes than that in their scalar counterparts. In the formation of spin textures, we have considered the theoretical model of a rapidly quenched and fast rotating trapped spin-1 Bose Einstein condensate, whose dynamics can be studied by solving the stochastic projected Gross-Pitaevskii equations. Spontaneous generation of nontrivial topological defects, such as the hexagonal lattice skyrmions and square lattice of half-quantized vortices was predicted. In particular, crystallization of merons （half skyrmions） can be generated in the presence of spin-orbit coupling.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10874249 and 11075223)
文摘This paper studies theoretically the spin evolution of a Bose-Einstein condensate starting from a mixture of two or three groups of 52Cr （spin-3） atoms in an optical trap. The initial state is so chosen that the condensate has total magnetization zero so that the system does not distinguish up and down. It is assumed that the system is very dilute （particle number is very small）, the temperature is very low, and the frequency of the harmonic trap is large enough. In these situations, the deviation caused by the neglect of the dipole-dipole interaction and by using the single-mode approximation is reduced. A theoretical calculation beyond the mean field theory is performed and the numerical results are helpful for the evaluation of the unknown strength go.
基金supported by the National Natural Science Foundation of China(Contract Nos.12375005 and 12235007)the Major Basic Research Program of Natural Science of Shaanxi Province(Grant No.2018KJXX-094).
文摘Exact analytical solutions are good candidates for studying and explaining the dynamics of solitons in nonlinear systems.We further extend the region of existence of spin solitons in the nonlinearity coefficient space for the spin-1 Bose-Einstein condensate.Six types of spin soliton solutions can be obtained,and they exist in different regions.Stability analysis and numerical simulation results indicate that three types of spin solitons are stable against weak noise.The non-integrable properties of the model can induce shape oscillation and increase in speed after the collision between two spin solitons.These results further enrich the soliton family for non-integrable models and can provide theoretical references for experimental studies.
文摘We study analytically the generation of maximally entangled states （MESs） formed by a two-component Bose-Einstein condensate （BEC） trapped in an adiabatically driven single potential well. Under the condition of the linear interaction controlled by a driven field being much stronger than the effective nonlinear interaction between the components, MESs, as some particular cases of superpositions of spin coherent states （SSCS）, may emerge periodically along with not only time evolution but also the equidifferent change of the linear coupling strength at a particular time.
文摘We consider a SU(3) spin–orbit coupled Bose–Einstein condensate confined in a harmonic plus quartic trap.The ground-state wave functions of such a system are obtained by minimizing the Gross–Pitaevskii energy functional, and the effects of the spin-dependent interaction and spin–orbit coupling are investigated in detail.For the case of ferromagnetic spin interaction, the SU(3) spin–orbit coupling induces a threefold-degenerate plane wave ground state with nontrivial spin texture.For the case of antiferromagnetic spin interaction, the system shows phase separation for weak SU(3) spin–orbit coupling, where three discrete minima with unequal weights in momentum space are selected, while hexagonal honeycomb lattice structure for strong SU(3) SOC, where three discrete minima with equal weights are selected.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0304203)the National Natural Science Foundation of China(Grant Nos.62020106014,62175140,61901249,92165106,12104276,and 62011530047)+4 种基金PCSIRT(Grant No.IRT17R70)the Educational Reform and Innovation Project of Higher Education in Shanxi Province,China(Grant Nos.Z20220001 and Z20220013)111 Project(Grant No.D18001)the Applied Basic Research Project of Shanxi Province(Grant Nos.201901D211191 and 201901D211188)the Shanxi 1331 KSC。
文摘We develop a research of spin currents in a^(23)Na spinor Bose–Einstein condensate(BEC)by applying a magnetic field gradient.The spin current is successfully induced by the spin-dependent force arising from the magnetic field gradient.The dynamics of the spin components under the magnetic force is investigated.The study is promising to be extended to produce a longer spin-coherence and to enhance the sensitivity of the spin-mixing interferometry in a spinor BEC.
文摘The experimental and theoretical research of spin-orbit-coupled ultracold atomic gases has advanced and expanded rapidly in recent years. Here, we review some of the progress that either was pioneered by our own work, has helped to lay the foundation, or has developed new and relevant techniques. Af- ter examining the experimental accessibility of all relevant spin-orbit coupling parameters, we discuss the fundamental properties and general applications of spin-orbit-coupled Bose-Einstein condensates （BECs） over a wide range of physical situations. For the harmonically trapped case, we show that the ground state phase transition is a Dicke-type process and that spin-orbit-coupled BECs provide a unique platform to simulate and study the Dicke model and Dicke phase transitions. For a homo- geneous BEC, we discuss the collective excitations, which have been observed experimentally using Bragg spectroscopy. They feature a roton-like minimum, the softening of which provides a potential mechanism to understand the ~round state phase transition. On the other hand, if the collective dy- namics are excited by a sudden quenching of the spin-orbit coupling parameters, we show that the resulting collective dynamics can be related to the famous Zitterbewegung in the relativistic realm. Finally, we discuss the case of a BEC loaded into a periodic optical potential. Here, the spin-orbit coupling generates isolated fiat bands within the lowest Bloch bands whereas the nonlinearity of the system leads to dynamical instabilities of these Bloch waves. The experimental verification of this instability illustrates the lack of Galilean invariance in the system.
