Chaotic escape dynamics of ultracold and Bose-condensed atoms

Kevin Mitchell, D. Steck

We consider the dynamic escape of a small packet of ultracold atoms launched from within an optical dipole trap. Based on a theoretical analysis of the underlying nonlinear dynamics, we predict that fractal behavior can be seen in experimental escape data. These data can be collected by measuring the time-dependent escape rate for packets launched over a range of angles. This fractal pattern is particularly well resolved below the Bose-Einstein transition temperature---a direct result of the extreme phase-space localization of the condensate. We predict that several self-similar layers of this novel fractal should be measurable, and we explain how this fractal pattern can be predicted and analyzed with recently developed techniques in symbolic dynamics.

R. A. Kidd

Jean Claude Garreau

Keye Zhang, Lu Zhou, Guangjiong Dong +1 more

We present a tutorial review on the topics related to current development in cavity optomechanics, with special emphasis on cavity optomechanical effects with ultracold gases, Bose-Einstein condensates, and spinor Bose-Einstein condensates. Topics including the quantum model and nonlinearity of the cavity optomechanics, the principles of optomechanical cooling, radiation-pressure-induced nonlinear states, the chaotic dynamics in a condensate-mirror-hybrid optomechanical setup, and the spin-mixing dynamics controlled by optical cavities are covered.

Jieli Qin

Abstract We theoretically investigate quantum tunnelling escape of a spin–orbit (SO)-coupled Bose–Einstein condensate (BEC) from a trapping well. The condensate is initially prepared in a quasi-one-dimensional harmonic trap. Depending on the system parameters, the ground state can fall in different phases—single minimum, separated or stripe. Then, suddenly the trapping well is opened at one side. The subsequent dynamics of the condensate is studied by solving nonlinear Schrödinger equations. We found that the diverse phases will greatly change the tunneling escape behavior of SO-coupled BECs. In the single minimum and separated phases, the condensate escapes the trapping well continuously, while in the stripe phase it escapes the well as an array of pulses. We also found that SO coupling has a suppressing effect on the tunnelling escape of atoms. Especially, for BECs without inter-atom interaction, the tunnelling escape can be almost completely eliminated when the system is tuned near the transition point between the single minimum and stripe phases. Our work thus suggests that SO coupling may be a useful tool to control the tunnelling dynamics of BECs, and potentially be applied in the realization of atom lasers and matter wave switches.

Roberto B. Diener