Measuring the gravitational acceleration with matter-wave velocimetry

Abstract

One of the major limitations of atomic gravimeters is represented by the vibration noise of the measurement platform, which cannot be distinguished from the relevant acceleration signal. We demonstrate a new method to perform an atom interferometry measurement of the gravitational acceleration without any need for a vibration isolation system or post-corrections based on seismometer data monitoring the residual accelerations at the sensor head. With two subsequent Ramsey interferometers, we measure the velocity variation of freely falling cold atom samples, thus determining the gravitational acceleration experienced by them. Our instrument has a fractional stability of 9 × 10 −6 at 1 s of integration time, one order of magnitude better than a standard Mach-Zehnder interferometer when operated without any vibration isolation or applied post-correction. Using this technique, we measure the gravitational acceleration in our laboratory, which is found in good agreement with a previous determination obtained with a FG5 mechanical gravimeter.

Testing gravity with cold atom interferometry: results and prospects

“…Several physical effects were investigated using atom interferometers. In particular, as described in the following, atom interferometry can be used in gravitational physics for measuring the gravity acceleration [9,11,20,25,[28][29][30][31][32][33][34][35], the gravity gradient [15,31,[36][37][38][39][40][41] and the gravity-field curvature [42,43], for the determination of the gravitational constant G [37,[44][45][46][47][48][49][50], for the investigation of gravity at microscopic distances [20,21,51], to search for dark matter [52,53], dark energy, chameleon and test theories of modified gravity [54][55][56]. Atom interferometry was used to test the weak equivalence principle of general relativity [57] by comparing the free fall of different atoms, 85 Rb vs 87 Rb [58][59][60][61],…”

New apparatus design for high-precision measurement ofG with atom interferometry

“…The experiment uses a Mach-Zehnder gravity gradiometer to measure the gravitational field experienced by the freely falling atoms. Two spatially separated atomic clouds of 87 Rb in free fall along the vertical axis are simultaneously interrogated by counter-propagating Raman lasers [6,29,36]. In our experiment, we probe rubidium atoms on the dipole transition 5S 1/2 − → 6P 3/2 instead of the usual D2 line.…”

“…Atom interferometry [1] has gained prominence due to a number of successful experiments carrying out precise measurements of the gravitational acceleration [2,3,4,5,6], curvature [7,8], gravity gradient [9,10,11,12,13,14,15], rotations [16,17,18,19], gravitational red shifts [20,21,22] as well as fundamental constants like h/m [23,24,25,26] and the Newtonian gravitational constant [27,28,29,30,31,32,33,34]. Atom interferometers are used for testing the Einstein's Equivalence Principle [35,36,37,38].…”

Sr atom interferometry with the optical clock transition as a gravimeter and a gravity gradiometer

“…In a single-photon atom interferometer, however, any optical component along the path connecting the clock laser to the atoms is a source of phase noise and the perfect isolation of all such optics is challenging. Nevertheless, schemes exist by which this noise (δφ P ) can be largely removed, for example by introducing a secondary independent sensor to act as a phase noise detector [47,48], and we ignore it in the following calculations. The effect of laser phase noise on the performance of a single-photon atom interferometer gravimeter can be quantitatively estimated through the sensitivity function method [49,50].…”