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Description
Ultracold atomic cloud is one of highly sensitive tools to search for undiscovered field as a quantum sensor in the vicinity of a surface [1, 2]. We have investigated interactions between ultracold atoms and a dielectric surface by an atomic fountain technique with moving an optical dipole trap beam. We initially loaded pre-cooled rubidium atoms to an optical dipole trap [3], and transported the atomic cloud with the temperature of 40 $\mu$K into a glass surface region by vertically changing the trap beam spatially. At the distance of 45 $\mu$m of the cloud from the glass surface, we suddenly turned off the trap beam with the initial velocity of 44 mm/s to generate the atomic fountain condition, and recaptured the atoms with experiences during their flights in the surface region in an evanescent light field near D2 line in the detuning range from -20 to +20 MHz. Thanks to the optical dipole and radiative forces near the resonance of the evanescent light, we derived slight differences of the numbers of recaptured atoms depending on the detuning. The differences are in good agreement with calculated results in the van der Waals and the Casimir-Polder potentials of the glass surface.
References:
[1] Athanasios Laliotis, Bing-Sui Lu, Martial Ducloy, and David Wilkowski, AVS Quantum Sci. 3, 043501 (2021).
[2] Kosuke Shibata, Satoshi Tojo, and Daniel Bloch, Optics Express 25, 9476 (2017).
[3] Taro Mashimo, Masashi Abe, and Satoshi Tojo, Phys. Rev. A 100, 064426 (2019).
