Isotope separation via atom optics in the Bragg regime

Joel Gomes Baptista, Louis Pagot, Sébastien Merlet +2 more

Quasi-Bragg regime is a good compromise for large-momentum-transfer atom interferometry, allowing for scaling up the interferometric area, while constraining the population of unwanted states. Separation of momentum states via standard time of flight methods, however, can be challenging when using laser-cooled atoms, rather than ultracold atoms with sub-recoil velocity distribution. To overcome this limit, we use Raman spectroscopy for stroboscopic sampling of the atomic state evolution in momentum space during the interrogating laser pulses. We quantitatively characterize atom optics employing two-photon (2___k) and multi-photon (6___k) Bragg transitions, the latter being optionally enhanced with optimal control protocol. We closely match the observed dynamics of the atomic state with simulations. Finally, we perform momentum spectroscopy of the output states in a 6___k Bragg gravimeter.

M. Jerkins, Isaac Chavez, Mark G. Raizen

Zixuan Zeng, Shangjin Li, Bo Yan

Due to the similar physical and chemical properties, isotopes are usually hard to separate. On the other hand, the isotope shifts are very well separated in a high-resolution spectrum, making them possible to be addressed individually by lasers, thus separated. Here we report such an isotope separation experiment with Potassium atoms. The isotopes are independently optical pumped to the desired spin states, and then separated with a Stern-Gerlach scheme. A micro-capillary oven is used to collimate the atomic beam, and a Halbach-type magnet array is used to deflect the desired atoms. Finally, the 40K is enriched by two orders of magnitude. This magneto-optical combined method provides an effective way to separate isotopes and can be extended to other elements if the relevant optical pumping scheme is feasible.

Muhammad Aqil, Farhan Saif

Anthony F. Bernhardt

Marion Jacquey, Alain Miffre, M Büchner +2 more

A magnetic field gradient applied to an atom interferometer induces a M -dependent phase shift which results in a series of decays and revivals of the fringe visibility. Using our lithium atom interferometer based on Bragg laser diffraction, we have measured the fringe visibility as a function of the applied gradient. We have thus tested the isotopic selectivity of the interferometer, the velocity selective character of Bragg diffraction for different diffraction orders as well as the effect of optical pumping of the incoming atoms. All these observations are qualitatively understood but a quantitative analysis requires a complete model of the interferometer.