Applications of atom interferometry using an improved laser cooling method

Using a novel method of Raman sideband cooling in a moving optical lattice followed by adiabatic release, atoms launched from a molasses are cooled to about 150 nK, a factor of 10 better than that obtained in the best molasses launch. The atoms move with a velocity spread of about 3 mm/s to a height of 1.3 m above the trap region. With these cold atoms, we have measured g, the acceleration due to gravity with a resolution of 60 parts per trillion after 2 days of integration time. This is performed with an atom interferometer using the π/2−π−π/2 sequence of stimulated Raman transition pulses with an interrogation time of 800 ms. The noise of a single launch of about a billion atoms is 1.0 × 10 −8 g, a factor of 2 better than any previous results.; Taking advantage of the long interferometer time, we have also measured the gravity gradient with a “double diamond” configuration using the π/2−π−π−π/2 pulse sequence. This is the first demonstration of a gravity gradient measurement using this method. The sensitivity is about 2 × 10−6s−2/$Hz$. A “triple diamond configuration” with π/2−π−π−π−π/2 pulse sequence is also demonstrated as a feasible method to measure gravity gradient. Different systematic effects that are important in these two methods are discussed. Proposals to obtain a more sensitive measurement in gravity gradient by simultaneously measuring the phase shifts of two groups of atoms launched in the same setup and in the fine structure constant by simultaneously measuring the recoils in atoms absorbing photons in opposite directions are presented.