Low-Energy Collective Excitation of Bose-Einstein Condensates in an Anisotropic Magnetic Trap

Andrew E. S. Barentine, Dan Lobser, Heather J. Lewandowski +1 more

T. Kimura

Lu Yang, Xiaorui Wang, Ke Li +3 more

We experimentally investigate the collective excitation of 87 Rb Bose–Einstein condensates confined in a cigar-shaped magnetic trap (QUIC trap). Using a method of magnetic perturbation, the center-of-mass oscillation of the condensate is excited, so that the radial trapping frequency of the QUIC trap can be precisely determined. A high-order excitation, characterized by a fast shape oscillation, also occurs simultaneously, with a noticeable damping in the oscillation amplitude compared with the oscillation of the center of mass. The measured oscillation frequencies, associated with these two low-energy excitation modes, agree well with theoretical predictions based on the Gross–Pitaevskii equation.

正人 大矢

M. S. Pindzola, Baoqing Sun

Collective modes of the ground and excited states of Bose?Einstein condensates are calculated by diagonalization of the Bogoliubov?de Gennes matrix in cylindrical coordinates. For an isotropic magnetic trap, the first breathing mode frequencies of the ground and dark soliton excited states are found to be in excellent agreement with a direct solution of the Gross?Pitaevskii equation with a time-dependent driving potential. In addition, the matrix diagonalization yields densities and frequencies for second breathing modes and higher order multipole modes. For an axially symmetric anisotropic trap, a considerable number of collective modes of the ground and dark soliton excited states are calculated. Prolate traps are found to have many more low-frequency multipolar modes than found in oblate traps for both ground and dark soliton excited states.

M. S. Pindzola, Frederic Texier

Collective modes of the ground and excited states of Bose–Einstein condensates are studied by numerical solution of the time-dependent Gross–Pitaevskii equation in three spatial dimensions. Scissors modes are studied by quadrupole excitation of the ground and excited states of 23 Na condensates in a fully anisotropic magnetic trap. The frequencies of the collective modes for the ground state condensates are found to be in good agreement with previous linear response theory. New results are presented for the frequencies of the collective modes for excited state condensates which exhibit solitary density depressions. A key to the proper characterization of the wide variety of dark-soliton states in atomic condensates is the experimental observation of collective modes.