38 research outputs found
Magneto-Optical Cooling of Atoms
We propose an alternative method to laser cooling. Our approach utilizes the
extreme brightness of a supersonic atomic beam, and the adiabatic atomic
coilgun to slow atoms in the beam or to bring them to rest. We show how
internal-state optical pumping and stimulated optical transitions, combined
with magnetic forces can be used to cool the translational motion of atoms.
This approach does not rely on momentum transfer from photons to atoms, as in
laser cooling. We predict that our method can surpass laser cooling in terms of
flux of ultra-cold atoms and phase-space density, with lower required laser
power and reduced complexity
Direct Observation of a Feshbach-resonance by Coincidence-detection of Ions and Electrons in Penning Ionization Collisions
Observation of molecular dynamics with quantum state resolution is one of the
major challenges in chemical physics. Complete characterization of collision
dynamics leads to the microscopic understanding and unraveling of different
quantum phenomena such as scattering resonances. We present a new experimental
approach for observing molecular dynamics involving neutral particles and ions
that is capable in providing state-to-state mapping of the dynamics. We use
Penning ionization reaction between argon and metastable helium to generate
argon ion and ground state helium atom pairs at separation of several
angstroms. The energy of ejected electron carries the information about the
initial electronic state of an ion. The coincidence detection of ionic products
provides a state resolved description of the post-ionization ion-neutral
dynamics. We demonstrate that correlation between the electron and ion energy
spectra enables us to directly observe the spin-orbit excited Feshbach
resonance state of HeAr. We measure the lifetime of the quasi-bound
HeAr A state and discuss possible applications of our method
Fano interference in quantum resonances from angle-resolved elastic scattering
Asymmetric spectral line shapes are a hallmark of interference of a quasi-bound state with a continuum of states. Such line shapes are well known for multichannel systems, for example, in photoionization or Feshbach resonances in molecular scattering. On the other hand, in resonant single channel scattering, the signature of such interference may disappear due to the orthogonality of partial waves. Here, we show that probing the angular dependence of the cross section allows us to unveil asymmetric Fano profiles also in a single channel shape resonance. We observe a shift in the peak of the resonance profile in the elastic collisions between metastable helium and deuterium molecules with detection angle, in excellent agreement with theoretical predictions from full quantum scattering calculations. Using a model description for the partial wave interference, we can disentangle the resonant and background contributions and extract the relative phase responsible for the characteristic Fano-like profiles from our experimental measurements
Single-Photon Molecular Cooling
We propose a general method to cool the translational motion of molecules.
Our method is an extension of single photon atomic cooling which was
successfully implemented in our laboratory. Requiring a single event of
absorption followed by a spontaneous emission, this method circumvents the need
for a cycling transition and can be applied to any paramagnetic or polar
molecule. In our approach, trapped molecules would be captured near their
classical turning points in an optical dipole or RF-trap following an
irreversible transition process