Séminaire / Seminar GReCO |
| « Quantum reflection from the Casimir-Polder potential and the gravitational behavior of antimatter » |
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G. Dufour |
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The GBAR experiment aims to study the gravitational properties of antimatter by timing the free fall of antihydrogen atoms in the Earth's gravity field. This will be done by dropping cold antihydrogen atoms onto an annihilation plate from 10-30 cm high. However, atoms in the vicinity of a material medium interact with that medium via the fluctuations of the electromagnetic field and experience an attractive Casimir-Polder force. In contrast with the classical expectation, an atomic wavepacket incident on the Casimir-Polder potential is partly reflected in the quantum regime.
I will present calculations of the Casimir-Polder potential between an antihydrogen atom and various surfaces, as well as the associated quantum reflection amplitudes. A particularly counter-intuitive phenomenon is that quantum reflection is enhanced on a medium interacting weakly with the electromagnetic field, such as nanoporous materials. We propose to use these highly reflective atom mirrors to hold (anti)atoms in gravitationally bound states, which are promising candidates for tests of the Equivalence Principle. In the second part of my talk I will present Liouville transformations which are maps between Schrödinger equations with identical scattering properties but which can be radically different from a semiclassical perspective. I will use a Liouville transformation to map quantum reflection onto an equivalent tunneling problem. Interestingly, in this new picture the counter-intuitive features of quantum reflection mentioned above are well understood. |
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lundi 15 juin 2015 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |