We present a new measurement of the Newtonian gravitational constant G based on cold atom interferometry. Freely falling samples of laser-cooled rubidium atoms are used in a gravity gradiometer to probe the field generated by nearby source masses. In addition to its potential sensitivity, this method is intriguing as gravity is explored by a quantum system. We report a value of G=6.667 10^{ -11} m^{ 3} kg^{ -1} s^{ -2}, estimating a statistical uncertainty of $\pm$ 0.011 10^{ -11} m^{ 3} kg^{ -1} s^{ -2} and a systematic uncertainty of $\pm$ 0.003 10^{ -11} m^{ 3} kg^{ -1} s^{ -2}. The long-term stability of the instrument and the signal-to-noise ratio demonstrated here open interesting perspectives for pushing the measurement accuracy below the 100 ppm level.
Categories: physics.atom-ph