Development of a continuously working gravity sensor

Abstract

Gravity sensors are indispensable devices for numerous applications in industry as well as in fundamental research. Recent efforts for improvement of gravimeters based on atom interferometry have achieved remarkable precision. A particularly attractive technique translates the force of gravitational acceleration in a frequency measurement of Bloch oscillations of laser-cooled atoms confined in a stationary vertical light wave. In modern gravimeters oscillations are measured via the state of the atoms after a variable evolution time. The measurement is destructive, and new atomic samples must be prepared for each preset evolution time. To overcome the destructive nature of the measurements in atomic gravimeters, we propose with this project a new technique that allows monitoring of the Bloch oscillations in vivo. The idea consists in letting the atoms interact with a high-finesse ring cavity operated in the regime of cavity quantum electrodynamics. With alkali atoms, which are more commonly used in experiments involving optical cooling, this system remains inaccessible for ring cavities, which by construction have macroscopic dimensions. We propose a way to circumvent this problem by using strontium atoms driven on their narrow intercombination line. The Instituto de Física de São Carlos combines technical expertise in the construction of high-finesse ring cavities and in the cooling and trapping of strontium. On the other hand, we are engaged in close collaborations with international research groups working in these areas. The undergraduate student Fagner Todão joined our group for a laboratory stage in August 2014 showing a continuously growing interest and a great talent in experimental physics. The desire he manifested in doing extended internships in foreign collaborating laboratories is a great opportunity not only for his formation but for our entire group, because this would reinforce the links we have with the foreign groups and facilitate mutual technology transfer. The fellowship will be inserted in the Projeto Temático FAPESP 2013/ 04162-5. (AU)