title: Blue-detuned optical ring trap for Bose-Einstein condensates based on conical refraction.
abstract: We present a novel approach for the optical manipulation of neutral atoms in annular light structures produced by the phenomenon of conical refraction occurring in biaxial optical crystals. For a beam focused to a plane behind the crystal, the focal plane exhibits two concentric bright rings enclosing a ring of null intensity called the Poggendorff ring. We demonstrate both theoretically and experimentally that the Poggendorff dark ring of conical refraction is confined in three dimensions by regions of higher intensity. We derive the positions of the confining intensity maxima and minima and discuss the application of the Poggendorff ring for trapping ultra-cold atoms using the repulsive dipole force of blue-detuned light. We give analytical expressions for the trapping frequencies and potential depths along both the radial and the axial directions. Finally, we present realistic numerical simulations of the dynamics of a87Rb Bose-Einstein condensate trapped inside the Poggendorff ring which are in good agreement with corresponding experimental results.
authors.forename: A
authors.initials: A
authors.lastname: Turpin
authors.forename: J
authors.initials: J
authors.lastname: Polo
authors.forename: Yu V
authors.initials: YV
authors.lastname: Loiko
authors.forename: J
authors.initials: J
authors.lastname: Küber
authors.forename: F
authors.initials: F
authors.lastname: Schmaltz
authors.forename: T K
authors.initials: TK
authors.lastname: Kalkandjiev
authors.forename: V
authors.initials: V
authors.lastname: Ahufinger
authors.forename: G
authors.initials: G
authors.lastname: Birkl
authors.forename: J
authors.initials: J
authors.lastname: Mompart