arXiv subjects

Martin Weitz

Publications and source records attributed to Martin Weitz.

76 records · Page 5Linked to original sources

arXiv2005

Interference of a variable number of coherent atomic sources

We have studied the interference of a variable number of independently created $m_F=0$ microcondensates in a CO$_{2}$-laser optical lattice. The observed average interference contrast decreases with condensate number N. Our experimental results agree well with the predictions of a random walk model. While the exact result can be given in terms of Kluyver's formula, for a large number of sources a $1/\sqrt{N}$ scaling of the average fringe contrast is obtained. This scaling law is found to be of more general applicability when quantifying the decay of coherence of an ensemble with N independently phased sources.

cond-mat.other↗

arXiv2005

Atomic Interferometer with Amplitude Gratings of Light and its Applications to Atom Based Tests of the Equivalence Principle

We have developed a matter wave interferometer based on the diffraction of atoms from effective absorption gratings of light. In a setup with cold rubidium atoms in an atomic fountain the interferometer has been used to carry out tests of the equivalence principle on an atomic basis. The gravitational acceleration of the two isotopes 85Rb and 87Rb was compared, yielding a difference Dg/g =(1.2 +-1.7)x10^{-7}. We also perform a differential free fall measurement of atoms in two different hyperfine states, and obtained a result of Dg/g =(0.4 +-1.2)x10^{-7}.

physics.atom-ph↗

arXiv2003

Bose-Einstein Condensation in a CO_2-laser Optical Dipole Trap

We report on the achieving of Bose-Einstein condensation of a dilute atomic gas based on trapping atoms in tightly confining CO_2-laser dipole potentials. Quantum degeneracy of rubidium atoms is reached by direct evaporative cooling in both crossed and single beam trapping geometries. At the heart of these all-optical condensation experiments is the ability to obtain high initial atomic densities in quasistatic dipole traps by laser cooling techniques. Finally, we demonstrate the formation of a condensate in a field insensitive m_F=0 spin projection only. This suppresses fluctuations of the chemical potential from stray magnetic fields.

cond-mat.soft↗

arXiv2003

All-Optical Realization of an Atom Laser

We demonstrate an atom laser using all-optical techniques. A Bose-Einstein condensate of rubidium atoms is created by direct evaporative cooling in a quasistatic dipole trap realized with a single, tightly focused CO$_{2}$-laser beam. An applied magnetic field gradient allows formation of the condensate in a field-insensitive $m_{F} = 0$ spin projection only, which suppresses fluctuations of the chemical potential from stray magnetic fields. A collimated and monoenergetic beam of atoms is extracted from the Bose-Einstein condensate by continuously lowering the dipole trapping potential in a controlled way to form a novel type of atom laser.

cond-mat.soft↗