We demonstrate a scheme for the Fourier synthesis of periodic optical
potentials with asymmetric unit cells for atoms. In a proof of principle
experiment, an atomic Bose-Einstein condensate is exposed to either symmetric
or sawtooth-like asymmetric potentials by superimposing a conventional standing
wave potential of $\lambda/2$ spatial periodicity with a fourth-order lattice
potential of $\lambda/4$ periodicity. The high periodicity lattice is realized
using dispersive properties of multiphoton Raman transitions. Future
applications of the demonstrated scheme could range from the search for novel
quantum phases in unconventionally shaped lattice potentials up to
dissipationless atomic quantum ratchets.Comment: 4 figure
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 CO2-laser beam. An applied magnetic field gradient allows the 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.
In this paper, we present a novel photoplethysmographic device that operates remotely, i.e. not in contact with the skin. The device allows for real time measurements of heart rate with motion artifact reduction from a distance of a few centimeters up to several meters. High mobility of users is achieved in assessment of vital body signs, such as heart rate.
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
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