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arXiv:hep-ph/0302239 · Journal of Physics G Nuclear and Particle Physics

Bouncing neutrons and the neutron centrifuge

P. J. S. Watson

Published Jun 12, 2003• 7 citations
arXivHTMLPDF

Abstract

The recent observation of the quantum state of the neutron bouncing freely under gravity allows some novel experiments. A possible method of purifying the ground state is given. We investigate two possible applications. It appears that the state could not be used to set better limits on the electric dipole moment of the neutron. However, it would be possible to use the state to set limits on modifications of gravity at short distances.

DOI
10.1088/0954-3899/29/7/311

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The recent observation of the quantum state of the neutron bouncing freely under gravity allows some novel experiments. A possible method of purifying the ground state is given. We investigate two possible applications. It appears that the state could not be used to set better limits on the electric dipole moment of the neutron. However, it would be possible to use the state to set limits on modifications of gravity at short distances.
Neutrons not only fall classically in the gravitational field of the Earth as potatoes and other normal objects do; at certain conditions, they reveal quantum behavior, or even form well­ defined gravitational quantum states. Due to the relative simplicity of quantum mechanical rules for solving this problem, we could predict analytically the motion of a neutron in a grav­ itational field in the vicinity of a reflecting surface. Such a bouncing neutron can have only certain, discrete values of energy. These extremely small energy values turn out to be very sensitive probes to the presence of even tiny extra interactions, in particular those between the neutron and the mirror. Moreover, several emerging fields of research profit from experi­ ence and knowledge gained in the recent experimental observation of gravitational quantum states of ultracold neutrons, and extend the developed methods to atoms and anti-atoms, to whispering-gallery effect and other domains, thus providing more and more application for the method. Quantum bouncing particles could play their role in quantum tests of the equivalence principle, in explorations of gravitational properties of antimatter, in searching for new funda­ mental short-range and other interactions beyond the Standard Model of particle physics, in surface and thin-layer physics, in chemistry, and so on. In this short note we mention results of a few previous years and project nearest developments ..
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