We have observed the stationary interference oscillations of a triple-entangled neutron state in an interferometric experiment. Time-dependent interaction with two radio-frequency (rf) fields enables coherent manipulation of an energy degree of freedom in a single neutron. The system is characterized by a multiply entangled state governed by a Jaynes-Cummings Hamiltonian. The experimental results confirm coherence of the manipulation as well as the validity of the description.
@article{arxiv.0803.3545,
title = {Coherent energy manipulation in single-neutron interferometry},
author = {S. Sponar and J. Klepp and R. Loidl and S. Filipp and G. Badurek and Y. Hasegawa and H. Rauch},
journal= {arXiv preprint arXiv:0803.3545},
year = {2008}
}