No Arabic abstract
In a region free of currents, magnetostatics can be described by the Laplace equation of a scalar magnetic potential, and one can apply the same methods commonly used in electrostatics. Here we show how to calculate the general vector field inside a real (finite) solenoid, using only the magnitude of the field along the symmetry axis. Our method does not require integration or knowledge of the current distribution, and is presented through practical examples, including a non-uniform finite solenoid used to produce cold atomic beams via laser cooling. These examples allow educators to discuss the non-trivial calculation of fields off-axis using concepts familiar to most students, while offering the opportunity to introduce important advancements of current modern research.
We present a novel slowing scheme for beams of laser-coolable diatomic molecules reminiscent of Zeeman slowing of atomic beams. The scheme results in efficient compression of the 1-dimensional velocity distribution to velocities trappable by magnetic or magneto-optical traps. 3D Monte Carlo simulations for the prototype molecule $^{88}mathrm{Sr}^{19}mathrm{F}$ and experiments in an atomic testbed demonstrate a performance comparable to traditional atomic Zeeman slowing and an enhancement of flux below v=35 m/s by a factor of $approx 20$ compared to white-light slowing. This is the first experimentally shown continuous and dissipative slowing technique in molecule-like level structures, promising to provide the missing link for the preparation of large ultracold molecular ensembles.
We describe the classical two dimensinal nonlinear dynamics of cold atoms in far-off-resonant donut beams. We show that there chaotic dynamics exists for charge greater than unity, when the intensity of the beam is periodically modulated. The two dimensional distributions of atoms in $(x,y)$ plane for charge two are simulated. We show that the atoms will acumulate on several ring regions when the system enters to regime of global chaos.
We report on an investigation of a method that applies simultaneously two different mathematical models in order to optimize the design of a Zeeman Slower towards the implementation of ultra cold atoms in solid state physics. We introduce the implementation of a finite element simulation that allows us to predict with great accuracy the magnetic field intensity profile generated by the proposed design. Through the prediction of the behavior of the Zeeman Slower a greater control is acquired, which allows the optimization of the different experimental variables. We applied the method in the design of a multilayer solenoidal Spin-Flip Zeeman Slower for strontium atoms. The magnetic intensity profile generated by the Zeeman Slower is in agreement with the magnetic field strength profile necessary for the atom cooling and tends to zero in both end sides. The latter terms are essential in order to optimize the amount of trapped and cooled atoms.
We report on the implementation of a dynamically configurable, servomotor- controlled, permanent magnet Zeeman slower for quantum optics experiments with ultracold atoms and molecules. This atom slower allows for switching between magnetic field profiles that are designed for different atomic species. Additionally, through feedback on the atom trapping rate, we demonstrate that computer-controlled genetic optimization algorithms applied to the magnet positions can be used in situ to obtain field profiles that maximize the trapping rate for any given experimental conditions. The device is lightweight, remotely controlled, and consumes no power in steady state; it is a step toward automated control of quantum optics experiments.
We present a thorough analysis of a Zeeman slower for sodium atoms made of permanent magnets in a Halbach configuration. Due to the orientation of the magnetic field, the polarisation of the slowing laser beam cannot be purely circular leading to optical leakages into dark states. To circumvent this effect, we propose an atomic state preparation stage able to significantly increase the performances of the Zeeman slower. After a careful theoretical analysis of the problem, we experimentally implement an optical pumping stage leading to an increase of the magneto-optical trap loading rate by 3.5. Such method is easy to set up and could be extended to other Zeeman slower architectures.