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Advances in High Energy Physics
Volume 2015, Article ID 173572, 7 pages
Research Article

Can We Observe the Gravitational Quantum States of Positronium?

1ETH Zurich, Institute for Particle Physics, Otto-Stern-Weg 5, 8093 Zurich, Switzerland
2Institut Laue-Langevin, 6 rue Jules Horowitz, 38046 Grenoble, France
3Lebedev Physical Institute, 53 Leninsky Prospect, Moscow 119991, Russia

Received 6 June 2014; Revised 17 August 2014; Accepted 29 August 2014

Academic Editor: Stefan Baessler

Copyright © 2015 P. Crivelli et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The publication of this article was funded by SCOAP3.


We consider the feasibility of observing the gravitational quantum states of positronium. The proposed scheme employs the flow-throw technique used for the first observation of this effect with neutrons. Collimation and Stark deceleration of Rydberg positronium atoms allow selecting the required velocity class. If this experiment could be realized with positronium, it would lead to a determination of for this matter-antimatter system at the few % level. As discussed in this contribution, most of the required techniques are currently available but important milestones have to be demonstrated experimentally before such an experiment could become reality. Those are the efficient focusing of a bunched positron beam, Stark deceleration of Rydberg positronium, and its subsequent excitation into states with large angular momentum. We provide an estimate of the efficiencies we expect for these steps and assuming those could be confirmed we calculate the signal rate.