Atom Interferometer Driven by a Picosecond Frequency Comb*

Light pulse atom interferometry is a cornerstone of high precision measurement. For decades, this technique enabled the measurement, with high precision, of gravity (acceleration, gradient, space curvature and gravitational constant) and the atomic recoil. A variety of new concepts and geometries for atom interferometry are in development around the world, paving the way for other applications such as the detection of gravitational waves in the low frequency range or the search of a signature of dark matter.

Until recently, light-pulse atom interferometry had only exploited continuous-wave (cw) laser sources. We demonstrate the implementation of a light pulse atom interferometer based on the diffraction of free-falling rubidium atoms by a frequency-comb laser [1]. We study the impact of the pulse length as well as of the interrogation time on the contrast of the fringes. A preliminary measurement of the Earth gravitational field g with a relative uncertainty of 10⁻⁷ is performed using this method. The technique we showed in the visible spectrum on rubidium can be extended to other spectral regions (deep-UV to X-UV) and therefore to new species. Since one can benefit from the high peak intensity of ultrashort pulses, which makes non-linear frequency conversion in crystals and gas targets more efficient.

Especially, the modest relative sensitivity on g that we demonstrated, if it were reproduced with anti-hydrogen, it would lead to an improved test of the interaction of anti-matter with gravity. We also demonstrate a new interferometer scheme where we are able to distinctly interrogate the atoms on each arm of the interferometer. In this talk, I will present the recent results of this work