The effect of an electric field E on a narrow quantum ring that contains two electrons and is threaded by a magnetic flux B has been investigated. Localization of the electronic distribution and suppression of the Aha...The effect of an electric field E on a narrow quantum ring that contains two electrons and is threaded by a magnetic flux B has been investigated. Localization of the electronic distribution and suppression of the AharonovBohm oscillation （ABO） are found in the two-electron ring, which are similar to those found in a one-electron ring. However, the period of ABO in a two-electron ring is reduced by half compared with that in a one-electron ring. Furthermore, during the variation of B, the persistent current of the ground state may undergo a sudden change in sign. This change is associated with a singlet-triplet transition and has no counterpart in one-electron rings. For a given E, there exists a threshold of energy. When the energy of the excited state exceeds the threshold, the localization would disappear and the ABO would recover. The value of the threshold is proportional to the magnitude of E. Once the threshold is exceeded, the persistent current is much stronger than the current of the ground state at E=0.展开更多
The wavefunctions that conserve the total spin are constructed for the fully condensed states and the states with one particle excited. A set of equations are deduced for the spatial longitudinal wavefunctions and the...The wavefunctions that conserve the total spin are constructed for the fully condensed states and the states with one particle excited. A set of equations are deduced for the spatial longitudinal wavefunctions and the chemical potentials. These equations are solved numerically for ^23Na and ^87Rb condensates. The deformed trap shows significant effects on the spectrum. This implies that the spin effect of the spinor BEC are more easily detected in an optical trap of larger aspect ratio.展开更多
The evolution of two-component cold atoms on a ring with spin-orbit coupling has been studied analytically for the case with N noninteracting particles. Then, the effect of interaction is evaluated numerically via a t...The evolution of two-component cold atoms on a ring with spin-orbit coupling has been studied analytically for the case with N noninteracting particles. Then, the effect of interaction is evaluated numerically via a two-body system. Two cases are considered： （i） Starting from a ground state the evolution is induced by a sudden change of the laser field, and （ii） the evolution starting from a superposition state. Oscillating persistent spin-currents have been found. A set of formulae have been derived to describe the period and amplitude of the oscillation. Based on these formulae the oscillation can be well controlled via adjusting the parameters of the laser beams. In particular, it is predicted that movable stripes might emerge on the ring.展开更多
An analysis of channel wave functions is made to clarify the types of resonance emerging from the Ps-Ps and Ps-Ps* collisions.The ordering of the energy levels of the states of the dipositronium is evaluated based on ...An analysis of channel wave functions is made to clarify the types of resonance emerging from the Ps-Ps and Ps-Ps* collisions.The ordering of the energy levels of the states of the dipositronium is evaluated based on the inherent nodal structures of wave functions and on the existing theoretical results.The existence of a few very probable low-lying narrower resonances,namely the 0^(+)_(1)(A_(2)),1^(-)_(1)(E),…,benefiting from the centrifugal barrier has been suggested.展开更多
A 6-boson system has been qualitatively studied based on symmetry consideration. Emphasis is placed on the ground rotation band based on the octahedron structure. In this band the L = 1 , 2, and 3 states are found to ...A 6-boson system has been qualitatively studied based on symmetry consideration. Emphasis is placed on the ground rotation band based on the octahedron structure. In this band the L = 1 , 2, and 3 states are found to be prohibited by symmetry. Therefore there is a gap to hinder the rotational excitation of the ground state.展开更多
Symmetry has imposed very strong constraints on the internal structure of quantum mechanical system.In particular,whether a state can access a given outgoing channel is constrained by symmetry.For the dipositroniums,t...Symmetry has imposed very strong constraints on the internal structure of quantum mechanical system.In particular,whether a state can access a given outgoing channel is constrained by symmetry.For the dipositroniums,the most important channel is the Ps-Ps channel.However,based on symmetry consideration it was found that only a few excited states are allowed to access the Ps-Ps channel,thereby at least the existence of two higher L=0 bound states(higher than the Ps-Ps threshold)has been affirmed.展开更多
The low-lying states of a spin-aligned 6-electron quantum dot may prefer the regular hexagon and regular centered pentagon structures.However,these favourable structures may be prohibited by inherent symmetry.Based on...The low-lying states of a spin-aligned 6-electron quantum dot may prefer the regular hexagon and regular centered pentagon structures.However,these favourable structures may be prohibited by inherent symmetry.Based on this consideration,a couple of equations are deduced.The solution of these equations gives exactly the magic numbers of the 6-electron dot.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10574163）, the Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Collisions, Lanzhou, China.
文摘The effect of an electric field E on a narrow quantum ring that contains two electrons and is threaded by a magnetic flux B has been investigated. Localization of the electronic distribution and suppression of the AharonovBohm oscillation （ABO） are found in the two-electron ring, which are similar to those found in a one-electron ring. However, the period of ABO in a two-electron ring is reduced by half compared with that in a one-electron ring. Furthermore, during the variation of B, the persistent current of the ground state may undergo a sudden change in sign. This change is associated with a singlet-triplet transition and has no counterpart in one-electron rings. For a given E, there exists a threshold of energy. When the energy of the excited state exceeds the threshold, the localization would disappear and the ABO would recover. The value of the threshold is proportional to the magnitude of E. Once the threshold is exceeded, the persistent current is much stronger than the current of the ground state at E=0.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10574163, 90306016 and 10674182.
文摘The wavefunctions that conserve the total spin are constructed for the fully condensed states and the states with one particle excited. A set of equations are deduced for the spatial longitudinal wavefunctions and the chemical potentials. These equations are solved numerically for ^23Na and ^87Rb condensates. The deformed trap shows significant effects on the spectrum. This implies that the spin effect of the spinor BEC are more easily detected in an optical trap of larger aspect ratio.
基金Project supported by the National Natural Science Foundation of China(Grant No.10874249)
文摘The evolution of two-component cold atoms on a ring with spin-orbit coupling has been studied analytically for the case with N noninteracting particles. Then, the effect of interaction is evaluated numerically via a two-body system. Two cases are considered： （i） Starting from a ground state the evolution is induced by a sudden change of the laser field, and （ii） the evolution starting from a superposition state. Oscillating persistent spin-currents have been found. A set of formulae have been derived to describe the period and amplitude of the oscillation. Based on these formulae the oscillation can be well controlled via adjusting the parameters of the laser beams. In particular, it is predicted that movable stripes might emerge on the ring.
基金Supported by the National Natural Science Foundation of China under Grant No.19875084.
文摘An analysis of channel wave functions is made to clarify the types of resonance emerging from the Ps-Ps and Ps-Ps* collisions.The ordering of the energy levels of the states of the dipositronium is evaluated based on the inherent nodal structures of wave functions and on the existing theoretical results.The existence of a few very probable low-lying narrower resonances,namely the 0^(+)_(1)(A_(2)),1^(-)_(1)(E),…,benefiting from the centrifugal barrier has been suggested.
基金the National Natural Science Foundation of China under Grant No.19875084the Research Fund for the Doctoral Program of Higher Education.
文摘A 6-boson system has been qualitatively studied based on symmetry consideration. Emphasis is placed on the ground rotation band based on the octahedron structure. In this band the L = 1 , 2, and 3 states are found to be prohibited by symmetry. Therefore there is a gap to hinder the rotational excitation of the ground state.
基金Supported by the National Natural Science Foundation of China under Grant No.19875084the fund of National Educational Committee of China。
文摘Symmetry has imposed very strong constraints on the internal structure of quantum mechanical system.In particular,whether a state can access a given outgoing channel is constrained by symmetry.For the dipositroniums,the most important channel is the Ps-Ps channel.However,based on symmetry consideration it was found that only a few excited states are allowed to access the Ps-Ps channel,thereby at least the existence of two higher L=0 bound states(higher than the Ps-Ps threshold)has been affirmed.
基金Supported by the National Natural Science Foundation of China under Grant No.19374073 and Grant No.19134020Guangdong Natural Science Foundation.
文摘The low-lying states of a spin-aligned 6-electron quantum dot may prefer the regular hexagon and regular centered pentagon structures.However,these favourable structures may be prohibited by inherent symmetry.Based on this consideration,a couple of equations are deduced.The solution of these equations gives exactly the magic numbers of the 6-electron dot.
