Quantum reflection of ultracold antihydrogen from a solid surface

We consider the interaction of antiatoms with a solid surface and present calculations of the reflection probability using the exact retarded potential for the antihydrogen impinging on the ideally conducting surface. We present the reflection probability as a function of collision energy and show that the sufficiently cold H-bar atoms are reflected (rather than annihilated) from the surface, which opens prospects for storing and guiding antiatoms between material walls. The reflection probability in the ultracold regime is determined entirely by the van der Waals-Casimir tail of the atom-wall interaction and contains information on the retardation effects. We argue on the possibility of exploiting the ultracold antihydrogen-surface interactions as a probe of the electrodynamical and gravitational properties of an antiatom. We found that the lifetime of cold H-bar bouncing on the surface in the gravitational field of Earth is τ = ℎ/(2Mg vertical bar Im a vertical bar) ≅ 0.11 s. The measurement of that lifetime in conjunction with our calculation of the scattering length a allows determination of the gravitational force Mg on the antihydrogen atom. (letter to the editor)