On the Problem of Existence of Collective Oscillations in Atoms

B.Kh. Ishmukhametov, Yu. A. Babanov

Maria Adamuti‐Trache

Sol Wieder, Sidney Borowitz

Maciej Lewenstein, Kazimierz Rza̧żewski

Collective radiation of several atoms represented by harmonic oscillators is analysed. When taking into account the near-zone field, the authors show that the existence of the super-radiant mode in the small-system limit is a rare phenomenon. Explicit calculations for four oscillators placed on the vertices of a tetrahedron are presented. Analogous results are obtained for two-level atoms in the case of small total excitation.

Andrew J. Robertson, Lei Jiang, Han Pu +2 more

We show that a robust macroscopic atom-molecule dark state can exist in fermionic systems, which represents a coherent superposition between the ground molecular Bose-Einstein condensates and the atomic BCS paired state. We take advantage of the tunability offered by external laser fields, and explore this superposition for demonstrating coherent oscillations between ground molecules and atom pairs. We interpret the oscillation frequencies in terms of the collective excitations of the dark state.

Fang-Qi Hu, Jianjun Wang, Zi-Fa Yu +2 more

We study the collective dynamics of the spin-orbit coupled two pseudospin components of a Bose-Einstein condensate trapped in a quasi-one-dimensional harmonic potential, by using variational and directly numerical approach of binary mean-field Gross-Pitaevskii equations. The results show that, because of strong coupling of spin-orbit coupling (SOC), Rabi coupling, and atomic interaction, the collective dynamics of the system behave as complex characters. When the Rabi coupling is absent, the density profiles of the system preserve the Gauss type and the wave packets do harmonic oscillations. The amplitude of the collective oscillations increases with SOC. Furthermore, when the SOC strength increases, the dipole oscillations of the two pseudospin components undergo a transition from in-phase to out-of-phase oscillations. When the Rabi coupling present, there will exist a critical value of SOC strength (which depends on the Rabi coupling and atomic interaction). If the SOC strength is less than this critical value, the density profiles of the system can preserve the Gauss type and the wave packets do anharmonic (the frequency of dipole oscillations depends on SOC) oscillations synchronously (i.e., in-phase oscillations). However, if the SOC strength is larger than this critical value, the wave packets are dynamically fragmented and the stable dipole oscillations of the system can not exist. The collective dynamics of the system can be controlled by adjusting the atomic interaction, SOC, and Rabi-coupling strength.