Speaker
Description
Atom interferometry involving cold ground-state atoms is well established for precisely measuring acceleration due to gravity, $g$, and testing the Weak Equivalence Principle (WEP) [1]. However, because of the short (142 ns) ground-state annihilation lifetime of positronium, to exploit analogous techniques to test antimatter gravity, to complement the 'free-fall' experiments with antihydrogen at CERN [2], and the WEP for this purely leptonic system, it is necessary to excite the atoms to Rydberg states with long lifetimes (>10 µs) [3]. Based upon these considerations, we have developed a scheme to measure acceleration due to gravity by Rydberg-atom interferometry. This uses a technique which is an electric analogue of magnetic Stern-Gerlach interferometry typically performed with paramagnetic ground state atoms [4]. This scheme involves preparing the atoms in superpositions of Rydberg states with different static electric dipole moments, and exerting state-dependent forces on them using inhomogeneous electric fields [5]. The effect of gravity on the evolution of the resulting superposition of momentum states can then be monitored to obtain a value for $g$. We will describe the design of this type of Rydberg-atom interferometer and outline how it can be operated to measure $g$ in experiments with helium and, in the longer term, positronium atoms.
[1] P. Asenbaum, C. Overstreet, M. Kim, J. Curti, and M. A. Kasevich Phys. Rev. Lett. 125, 191101 (2020)
[2] Anderson, E.K., Baker, C.J., Bertsche, W. et al., Nature 621, 716–722 (2023)
[3] A. Deller, B. S. Cooper, S. D. Hogan and D. B. Cassidy, Phys. Rev. A 93, 062513 (2016)
[4] Y. Margalit, O. Dobkowski, Z. Zhou, O. Amit, Y. Japha, S. Moukouri, D. Rohrlich, A. Mazumdar, S. Bose, C. Henkel, R. Folman, Sci. Adv 7, 22 (2021)
[5] J. E. Palmer and S. D. Hogan, Phys. Rev. Lett 122, 250404 (2019); J. D. R. Tommey and S. D. Hogan, Phys. Rev. A 104, 033305 (2021)
