This paper proposes a method for calculating the Landau damping of a low-energy collective mode in a harmonically trapped Bose-Einstein condensate. Based on the divergence-free analytical solutions for ground-state wa...This paper proposes a method for calculating the Landau damping of a low-energy collective mode in a harmonically trapped Bose-Einstein condensate. Based on the divergence-free analytical solutions for ground-state wavefunction of the condensate and eigenvalues and eigenfunctions for thermally excited quasiparticles, obtained beyond Thomas-Fermi approximation, this paper calculates the coupling matrix elements describing the interaction between the collective mode and the quasiparticles. With these analytical results this paper evaluates the Landau damping rate of a monopole mode in a spherical trap and discusses its dependence on temperature, particle number and trapping frequency of the system.展开更多
We calculate the spin and density susceptibility ofWeyl fermions with repulsive S-wave interaction in ultracold gases.Weyl fermions have a linear dispersion,which is qualitatively different from the parabolic dispersi...We calculate the spin and density susceptibility ofWeyl fermions with repulsive S-wave interaction in ultracold gases.Weyl fermions have a linear dispersion,which is qualitatively different from the parabolic dispersion of conventional materials.We find that there are different collective modes for the different strengths of repulsive interaction by solving the poles equations of the susceptibility in the random-phase approximation.In the long-wavelength limit,the sound velocity and the energy gaps vary with the different strengths of the interaction in the zero sound mode and the gapped modes,respectively.The particle-hole continuum is obtained as well,where the imaginary part of the susceptibility is nonzero.展开更多
This paper presents a scheme for realizing the frequency up-conversion between two collective atomic modes. In the scheme two atomic samples are coupled to a cavity mode. Under the large detuning condition, the two co...This paper presents a scheme for realizing the frequency up-conversion between two collective atomic modes. In the scheme two atomic samples are coupled to a cavity mode. Under the large detuning condition, the two collective atomic modes are coupled via the virtual excitation of the cavity mode and the effective Hamiltonian corresponds to the frequency up-conversion. In the scheme the cavity mode is only virtually excited and thus the process is insensitive to cavity decay.展开更多
基金Project supported by the National Nature Science Foundation of China （Grant Nos 90403008 and 10434060）, and State Key Development Program for Basic Research of China （Grant No 2005CB724508）.
文摘This paper proposes a method for calculating the Landau damping of a low-energy collective mode in a harmonically trapped Bose-Einstein condensate. Based on the divergence-free analytical solutions for ground-state wavefunction of the condensate and eigenvalues and eigenfunctions for thermally excited quasiparticles, obtained beyond Thomas-Fermi approximation, this paper calculates the coupling matrix elements describing the interaction between the collective mode and the quasiparticles. With these analytical results this paper evaluates the Landau damping rate of a monopole mode in a spherical trap and discusses its dependence on temperature, particle number and trapping frequency of the system.
基金Project supported by the National Natural Science Foundation of China(Grant No.2016YFA0301500).
文摘We calculate the spin and density susceptibility ofWeyl fermions with repulsive S-wave interaction in ultracold gases.Weyl fermions have a linear dispersion,which is qualitatively different from the parabolic dispersion of conventional materials.We find that there are different collective modes for the different strengths of repulsive interaction by solving the poles equations of the susceptibility in the random-phase approximation.In the long-wavelength limit,the sound velocity and the energy gaps vary with the different strengths of the interaction in the zero sound mode and the gapped modes,respectively.The particle-hole continuum is obtained as well,where the imaginary part of the susceptibility is nonzero.
基金supported by the Doctoral Foundation of the Ministry of Education of China (Grant No 20070386002)
文摘This paper presents a scheme for realizing the frequency up-conversion between two collective atomic modes. In the scheme two atomic samples are coupled to a cavity mode. Under the large detuning condition, the two collective atomic modes are coupled via the virtual excitation of the cavity mode and the effective Hamiltonian corresponds to the frequency up-conversion. In the scheme the cavity mode is only virtually excited and thus the process is insensitive to cavity decay.
