Determination of the Newtonian Gravitational Constant Using Atom Interferometry

摘要: We present a new measurement of the Newtonian gravitational constant G based on cold-atom interferometry. Freely falling samples laser-cooled rubidium atoms are used in gravity gradiometer to probe field generated by nearby source masses. In addition its potential sensitivity, this method is intriguing as explored quantum system. report value � 6:667 10 11 m 3 kg 1 s 2 , estimating statistical uncertainty 0:011 and systematic 0:003 . The long-term stability instrument signal-tonoise ratio demonstrated here open interesting perspectives for pushing accuracy below 100 ppm level. one most measured fundamental physical constants at same time least precisely known. Improving knowledge has not only pure metrological interest, but also important key role that it plays theories gravitation, cosmology, particle physics, geophysical models, astrophysical observations. However, extreme weakness force impossibility shielding effects make difficult measure G, while keeping well under control. Many measurements performed date traditional torsion pendulum [1], direct derivation historical experiment Cavendish 1798. Recently, many groups have set up experiments different concepts with completely systematics: beam-balance system [2], laser interferometry acceleration freely test mass [3], Fabry-Perot or microwave cavities [4,5]. precise available today still show substantial discrepancies, limiting 2006 CODATA recommended part 4 From point view, realization conceptually can help identify hidden therefore improve confidence final result. Cold-atom outstanding performances tiny rotations accelerations, widely applications: precision [6], gradient [7], rotation Earth [8,9], tests Einstein’s weak equivalence principle [10], Newton’s law short distances [11], [12,13]. Applications these techniques physics space study [14]. Letter, we determination An atomic differential experienced two influence tungsten repeated configurations masses modeled numerical simulation. evolution wave packets distribution masses, evaluate expected acceleration, having unique free parameter. Avalue finally extracted comparing experimental data simulations. Proof-of-principle similar schemes using lead were already presented [15,16]. work, specific efforts been devoted control related trajectories, positioning stray fields. particular, FIG. (color online). Schematic showing setup Raman beams propagating along vertical direction. During measurement, position alternated between configuration C1 (left) C2 (right). PRL 100, 050801 (2008)