Atom interferometry with top-hat laser beams

Abstract

The uniformity of the intensity and phase of laser beams is crucial to high-performance atom interferometers. Inhomogeneities in the laser intensity profile cause contrast reductions and systematic effects in interferometers operated with atom sources at micro-Kelvin temperatures, and detrimental diffraction phase shifts in interferometers using large momentum transfer beam splitters. We report on the implementation of a socalled top-hat laser beam in a long-interrogation-time cold-atom interferometer to overcome the issue of the inhomogeneous laser intensity encountered when using Gaussian laser beams. We characterize the intensity and relative phase profiles of the top-hat beam and demonstrate its gain in atom-optics efficiency over a Gaussian beam, in agreement with numerical simulations. We discuss the application of top-hat beams to improve the performance of different architectures of atom interferometers.

Mollow triplet in cold atoms

“…This corresponds to a first essential step if one then wants to turn to the search of more exotic effects. One can also note that, while temperature broadening effect is inherent to the cold atomic cloud, the effect of the laser profile could be removed or at least reduced by using for example a top-hat laser beam [32]. Off resonance, the two Mollow sidebands were observed as well, yet in this case the central peak mainly corresponds to Doppler-broadened elastic scattering.…”

Atomic source selection in space-borne gravitational wave detection

“…The excitation probability is intimately connected to the phase space properties of the atomic cloud. An intensity profile of the exciting beam that varies over the spatial extent of the ensemble induces a spacedependent Rabi frequency except when the laser beam is shaped to be spatially uniform [40,41]. One can overcome it by an increased beam waist leading to a homogeneous but smaller Rabi frequency.…”

Differential interferometry using a Bose-Einstein condensate

“…Higher velocities v sep and longer times T , however, require optical lattices with larger waists, and, thus more laser power. Compared to Gaussian beams, flattop shaped profiles show the advantageous feature of a more equal and efficient distribution of laser power over the interferometry region [55], which benefits the scheme presented here. Table 1 shows the sensitivities for our current setup and two scenarios for future applications.…”