Results 21 to 30 of about 101,744 (75)

Metastability of persistent currents in trapped gases of atoms [PDF]

Phys. Rev. A 76 (2007) 043627, 2007
We examine the conditions that give rise to metastable, persistent currents in a trapped Bose-Einstein condensate. A necessary condition for the stability of persistent currents is that the trapping potential is not a monotonically increasing function of the distance from the trap center.
arxiv   +1 more source

Optical trap potential control in N-type four level atoms by femtosecond Gaussian pulses [PDF]

, 2014
In this work we present a scheme to control the optical dipole trap potential in an N-type four-level atomic system by using chirped femtosecond Gaussian pulses. The spatial size of the trap can be well controlled by tuning the beam waist of the Gaussian pulse and the detuning frequency.
arxiv   +1 more source

Efficient Direct Evaporative Cooling in an Atom Chip Magnetic Trap [PDF]

, 2013
We demonstrate direct evaporative cooling of $^{87}$Rb atoms confined in a dimple trap produced by an atom chip. By changing the two chip currents and two external bias fields, we show theoretically that the trap depth can be lowered in a controlled way with no change in the trap frequencies or the value of the field at the trap center. Experimentally,
arxiv   +1 more source

FLUX-TRAP REACTOR WITH ABSORBER IN THE CENTER [PDF]

, 1958
An idealized flux-trap reactor is modified by the insertion of absorber. It is shown that, for appreciable absorption, a flux depression results, and the remaining flux is proportional to the diffusion constant D times the center flux in the nonabsorption case. This factor D just cancels the factor 1/D in the expression for this center flux so that the
openaire   +3 more sources

Observation of cooperatively enhanced atomic dipole forces from NV centers in optically trapped nanodiamonds [PDF]

, 2015
Since the early work by Ashkin in 1970, optical trapping has become one of the most powerful tools for manipulating small particles, such as micron sized beads or single atoms. The optical trapping mechanism is based on the interaction energy of a dipole and the electric field of the laser light.
arxiv   +1 more source

Vortices near the Mott phase of a trapped Bose-Einstein condensate [PDF]

, 2008
We present a theoretical study of vortices within a harmonically trapped Bose-Einstein condensate in a rotating optical lattice. We find that proximity to the Mott insulating state dramatically effects the vortex structures. To illustrate we give examples in which the vortices: (i) all sit at a fixed distance from the center of the trap, forming a ring,
arxiv   +1 more source

Bose condensation of interacting gases in traps with and without optical lattice [PDF]

, 2008
We discuss effects of particle interaction on Bose condensation in inhomogeneous traps with and without optical lattice. Interaction pushes normal particles away from the condensate droplet, which is located in the center of the trap, towards the periphery of the trap where the trapping potential is large. In the end, the remaining normal particles are
arxiv   +1 more source

Loading an Optical Trap with Diamond Nanocrystals Containing Nitrogen-Vacancy Centers from a Surface [PDF]

arXiv, 2015
We present a simple and effective method of loading particles into an optical trap in air at atmospheric pressure. Material which is highly absorptive at the trapping laser wavelength, such as tartrazine dye, is used as media to attach photoluminescent diamond nanocrystals.
arxiv  

Particle Dynamics in Damped Nonlinear Quadrupole Ion Traps [PDF]

, 2014
We examine the motions of particles in quadrupole ion traps as a function of damping and trapping forces, including cases where nonlinear damping or nonlinearities in the electric field geometry play significant roles. In the absence of nonlinearities, particles are either damped to the trap center or ejected, while their addition brings about a rich ...
arxiv   +1 more source

Trapped fermion mixtures with unequal masses: a Bogoliubov-de Gennes approach [PDF]

arXiv, 2008
We use the Bogoliubov-de Gennes formalism to analyze the ground state phases of harmonically trapped two-species fermion mixtures with unequal masses. In the weakly attracting limit and around unitarity, we find that the superfluid order parameter is spatially modulated around the trap center, and that its global maximum occurs at a finite distance ...
arxiv