Motion of an atom under the effect of femtosecond laser pulses: From chaos to spatial localization

The spatial localization of an atom in a field of periodic femtosecond laser pulses is considered. It has been shown that the atom can be localized with absolute accuracy in the nanometer range. The time interval during which the atom is situated in the laser field is only 10^?7–10^?8 of the total localization time interval.     

Imaging and focusing of an atomic beam with a large period standing light wave

A novel atomic lens scheme is reported. A cylindrical lens potential was created by a large period ( 45 m) standing light wave perpendicular to a beam of metastable He atoms. The lens aperture (25 m) was centered in one antinode of the standing wave; the laser frequency was nearly resonant with the atomic transition 2³ S ₁–2³ P ₂ (=1.083 m) and the interaction time was significantly shorter than the spontaneous lifetime (100 ns) of the excited state. The thickness of the lens was given by the laser beam waist (40 m) in the direction of the atomic beam. Preliminary results are presented, where an atomic beam is focused down to a spot size of 4 m. Also, a microfabricated grating with a period of 8 m was imaged. We discuss the principle limitations of the spatial resolution of the lens given by spherical and chromatic aberrations as well as by diffraction. The fact that this lens is very thin offers new perspectives for deep focusing into the nm range.     

Magnetooptical compression of atomic beams

We consider the propagation of an atomic beam in a quadrupole magnetic field under transverse irradiation by a cooling laser field. The cooling laser field was chosen in the form of a two-dimensional σ⁺-σ^? configuration. We show that the sub-Doppler resonance in the radiation force can be used to reduce the diameter of the atomic beam to a value on the order of 10 mm. We establish that the simultaneous transverse cooling and compression of the atomic beam allow its phase density to be increased to values of the order of 10^?4–10^?3. The dipole interaction of an atom with the cooling and compressing laser field in a quadrupole magnetic field is analyzed in terms of a simple (3 + 5)-level model atom.

     

Intense stationary flow of cold atoms formed by laser deceleration of atomic beam

Applying an optimum configuration of atomic and laser beams, a powerful two-frequency laser and restriction of velocity diffusion permitted us to obtain an intense stationary flow of atoms with an effective temperature down to 1 K. The decelerated atomic beam intensity exceeds that of the initial atomic beam by more than 3 x 10³.     

Laser spectroscopy with a cooler ring at the esr (GSI) and the TSR (MPI Heidelberg)

At the TSR cooler ring at Heidelberg, laser studies were carried out using singly charged lithium and beryllium ions. Laser spectroscopy of relativistic lithium ions (v=0.04c) yielded signals with a narrow linewidth, suitable for an experimental test of special relativity. A dramatic reduction of the beam temperature, as defined by the longitudinal velocity spread, was achieved via laser cooling in both cases. At the ion energies available at ESR it will become possible to prepare and store bare ions up to U⁹²⁺. Electron cooling was succesfully demonstrated for hydrogen-like Bi⁸²⁺ ions, where a laser experiment is scheduled to study the ground-state hyperfine splitting.     

Zeeman laser cooling of <Superscript>85</Superscript>Rb atoms in transverse magnetic field

The process of Zeeman laser cooling of ⁸⁵Rb atoms in a new scheme employing a transverse magnetic field has been experimentally studied. Upon cooling, the average velocity of atoms was 12 m/s at a beam intensity of 7.2×10¹² s^?1 and an atomic density of 4.7×10¹⁰ cm^?3.     

Atomic cavity with light-induced mirrors

We consider a possibility of creating an atomic cavity on the basis of reflection of atoms from a laser field. The main parameters of cavity such as maximum and minimum atomic velocity, cavity stability, scheme of atomic injection, maximum atomic density were defined. It was shown that a high degeneracy of atoms (1) can be achieved in such cavity.     

Focusing of an atomic beam by a Fresnel atom microlens

Focusing of an atomic beam by a Fresnel atom microlens formed by an optical field diffracted by an aperture whose size is comparable to or greater than the radiation wavelength is considered. It is shown that the dipole gradient force enables one to focus the atomic beam to a spot of about 10 nm in diameter. The focusing properties of a Fresnel atom microlens are analyzed within a model describing the dipole interaction of rubidium atoms with monochromatic radiation near the D-line.