A toroidal trap for cold 87Rb{}^{87}{Rb}87Rb atoms using an rf-dressed quadrupole trap (original) (raw)

Trapping and cooling of rf-dressed atoms in a quadrupole magnetic field

Journal of Physics B: Atomic, Molecular and Optical Physics, 2007

We observe the spontaneous evaporation of atoms confined in a bubble-like rf-dressed trap . The atoms are confined in a quadrupole magnetic trap and are dressed by a linearly polarized rf field. The evaporation is related to the presence of holes in the trap, at the positions where the rf coupling vanishes, due to its vectorial character. The final temperature results from a competition between residual heating and evaporation efficiency, which is controlled via the height of the holes with respect to the bottom of the trap. The experimental data are modeled by a Monte-Carlo simulation predicting a small increase in phase space density limited by the heating rate. This increase was within the phase space density determination uncertainty of the experiment.

Systematic study of the rf-induced evaporation of 87Rb atoms in a spherical magnetic quadrupole trap

Journal of the Korean Physical Society, 2012

We trap 87 Rb atoms in a spherical magnetic quadrupole potential consisting of a pair of anti-Helmholtz coils. The number of trapped atoms is 2.16(7) × 10 8 , and the lifetime is 26 seconds. The number, the temperature and the size of the atoms in a magnetic trap are controlled by the forced rfevaporative cooling technique. We obtain a sub-Doppler temperature of 33.7(5) μK in these atoms at an evaporation frequency of 4.2 MHz in the magnetic quadrupole trap. We discuss the properties of the atoms in the spherical magnetic quadrupole trap and the results of the rf-evaporation process.

Electromagnetic trapping of cold atoms

Reports on Progress in Physics, 2000

This review describes the methods of trapping cold atoms in electromagnetic fields and in the combined electromagnetic and gravity fields. We discuss first the basic types of the dipole radiation forces used for cooling and trapping atoms in the laser fields. We outline next the fundamentals of the laser cooling of atoms and classify the temperature limits for basic laser cooling processes. The main body of the review is devoted to discussion of atom traps based on the dipole radiation forces, dipole magnetic forces, combined dipole radiation-magnetic forces, and the forces combined of the dipole radiation-magnetic and gravity forces. Physical fundamentals of atom traps operating as waveguides and cavities for cold atoms are also considered. The review ends with the applications of cold and trapped atoms in atomic, molecular and optical physics.

RF spectroscopy in a resonant RF-dressed trap

Journal of Physics B: Atomic, Molecular and Optical Physics, 2010

We study the spectroscopy of atoms dressed by a resonant radiofrequency (RF) field inside an inhomogeneous magnetic field and confined in the resulting adiabatic potential. The spectroscopic probe is a second, weak, RF field. The observed line shape is related to the temperature of the trapped cloud. We demonstrate evaporative cooling of the RF-dressed atoms by sweeping the frequency of the second RF field around the Rabi frequency of the dressing field.

A lattice of magneto-optical and magnetic traps for cold atoms

2003

Basic periodic trapping configurations is presented, which can be realized with multilayer microstructures. The trapping fields for the atoms (Ioffe Pritchard type potentials for magnetic trapping of atoms as well as quadrupole fields for magneto-optical trapping) are formed by two layers of crossed wires, which can be individually addressed. The possibility of producing multiple magneto optical traps (MOT) next to a surface in a controlled manner will be shown. This could be a first step to load ultracold atoms into an array of microstructured magnetic traps in a parallel way.

An off-axis rotating atom trap

Optics Express, 2006

We present a novel configuration of a magneto-optical trap for cold atoms. The trap is very simple in design, employing only a small permanent magnet and an external Helmholtz bias coil. The trap's principal advantage is that the entire volume of the overlapping laser beams can be used for atom guiding and manipulation. An especially interesting effect is the rotation of the trapped atoms in circular motion as the permanent magnet is rotated. Clouds containing on the order of 2*10 6 atoms are rotated up to 60Hz forming a 5 mm diameter ring. This rotation can potentially be used in studying the behavior of cold atoms in 2-dimensional potential as well as applications for rotational sensors. We also present a classical theoretical model to simulate the experiment.

Dynamically controlled toroidal and ring-shaped magnetic traps

Physical Review A, 2007

We present magnetic traps with toroidal (T 2) and ring-shaped topologies. The trapping potential of a ring-shaped magnetic quadrupole field is modified by radio-frequency fields, resulting in adiabatic potentials for the dressed Zeeman states. Simple adjustment of the radio-frequency fields provides versatile possibilities for dynamical parameter tuning, topology change, and controlled potential perturbation. We show how toroidal and poloidal rotations can be induced, and demonstrate the feasibility of preparing degenerate quantum gases with reduced dimensionality and periodic boundary conditions. The great level of dynamical control is useful for atom interferometry.

Studies on cold atoms trapped in a Quasi-Electrostatic optical dipole trap

Journal of Physics: Conference Series, 2007

We discuss the results of measurements of the temperature and density distribution of cold Rubidium atoms trapped and cooled in an optical dipole trap formed by focussed CO2 laser beams at a wavelength of 10.6 µmfrom a cold, collimated and intense atomic beam of flux 2 × 10 10 atoms/s produced using an elongated 2D + MOT. A large number of rubidium atoms (≥ 10 10) were trapped in the MOT and the number density of atoms were further increased by making a temporal dark MOT to prevent density-limiting processes like photon rescattering by atoms at the trap centre. Subsequently, between 10 7 to 10 8 cold atoms at a temperature below 30 µK were transferred into a Quasi-Electrostatic trap (QUEST) formed by focussed CO2 laser beams at the MOT centre. Both single beam and crossed dual beam dipole traps were studied with a total output power of 50 W from the CO2 laser with focal spot sizes less than 100 microns. Various measurements were done on the cold atoms trapped in the dipole trap. The total atom number in the dipole trap and the spatial atom number density distribution in the trap was measured by absorption imaging technique. The temperature was determined from time-of-flight (TOF) data as well as from the absorption images after ballistic expansion of the atom cloud released from the dipole trap. The results from measurements are used to maximize the initial phase-space density prior to forced evaporative cooling to produce a Bose-Einstein Condensate.

Intense source of cold Rb atoms from a pure two-dimensional magneto-optical trap

Physical Review A, 2002

We present a two-dimensional ͑2D͒ magneto-optical trap ͑MOT͒ setup for the production of a continuous collimated beam of cold 87 Rb atoms out of a vapor cell. The underlying physics is purely two-dimensional cooling and trapping, which allows for a high flux of up to 6ϫ10 10 atoms/s and a small divergence of the resulting beam. We analyze the velocity distribution of the 2D MOT. The longitudinal velocity distribution of the atomic beam shows a broad feature ͑full width at half maximum Ӎ75 m/s), centered around 50 m/s. The dependence of the flux on laser intensity, on geometry of the trapping volume, and on pressure in the vapor cell was investigated in detail. The influence of the geometry of the 2D MOT on the mean velocity of the cold beam has been studied. We present a simple model for the velocity distribution of the flux based on rate equations describing the general features of our source.