Complex quantum dynamics of a toy system: cold atoms in optical potentials

C. Grynberg, J.-Y. Courtois, Brahim Lounis +2 more

William G. Williams

M. T. Greenaway, Alexander G. Balanov, T. M. Fromhold

We show theoretically that the dynamics of cold atoms in the lowest-energy band of a stationary optical lattice can be transformed and controlled by a second, weaker, periodic potential moving at a constant speed along the axis of the stationary lattice. The atom trajectories exhibit complex behavior, which depends sensitively on the amplitude and speed of the propagating lattice. When the speed and amplitude of the moving potential are low, the atoms are dragged through the static lattice and perform drifting orbits with frequencies an order of magnitude higher than that corresponding to the moving potential. Increasing either the speed or amplitude of the moving lattice induces Bloch-like oscillations within the energy band of the static lattice, which exhibit complex resonances at critical values of the system parameters. In some cases, a very small change in these parameters can reverse the atom's direction of motion. In order to understand these dynamics we present an analytical model, which describes the key features of the atom transport and also accurately predicts the positions of the resonant features in the atom's phase space. The abrupt controllable transitions between dynamical regimes, as well as the associated set of resonances, provide a mechanism for transporting atoms between precise locations in a lattice, as required for using cold atoms to simulate condensed matter or as a stepping stone to quantum information processing. The system also provides a direct quantum simulator of acoustic waves propagating through semiconductor nanostructures in sound analogs of the optical laser (saser).

Ariel Kaplan, Mikkel F. Andersen, Friedman, Nir +1 more

We present a new experimental system (the ``atom-optics billiard'') and demonstrate chaotic and regular dynamics of cold, optically trapped atoms. We show that the softness of the walls and additional optical potentials can be used to manipulate the structure of phase space.

Andrew G. Truscott, W. K. Hensinger, M. E. J. Friese +2 more

Guillaume Gauthier, Issac Lenton, Mark A. Baker +3 more

Configurable trapping potentials are of great interest in cold atom physics, as they enable production of dynamical highly flexible fields that exhibit unprecedented stability and diverse geometries. Direct imaging can be used to create large area trapping potentials but is often overlooked due to its inability to correct for wavefront aberrations of the optical system [1]. This need not be a major disadvantage for a well-corrected optical system and brings advantages including the simplicity and speed of direct imaging. This is in contrast to the Fourier plane method which requires complex calculations to generate proper holograms and suffers from phase defects and speckle. For applications in cold atom trapping, these effects are especially detrimental as the atoms are sensitive to perturbations at the ~1% level of the optical potential. Our approach uses off-the-shelf lenses and microscope objectives and is able to achieve 630(10) nm full width half maximum (FWHM) patterning resolution using a 0.45 NA objective, within 5% of the diffraction limit of the system, while imaging through 1.25 mm of glass. The light field patterning is done using a digital micromirror device (DMD) which allows for dynamic trapping potentials due to its ability to store 13,889 frames and its 22 kHz full frame refresh rate. We use this method to pattern planar potentials for the purpose of cold atom experiments and have found that for atoms, which tend to respond relatively slowly to perturbations, it is possible to combine half-toning and time averaging to produce grey scale patterns, additionally allowing for pattern correction [2]. [1] P. C. Mogensen and J. Glückstad, Optics Communications 175, 75–81 (2000). [2] G. Gauthier, I. Lenton, N. McKay Parry, M. Baker, M. J. Davis, H. Rubinsztein-Dunlop, and T. W. Neely, arXiv preprint arXiv:1605.04928 (2016).