Speaker
Description
Antihydrogen is an exciting system to perform tests of fundamental physics by comparing it with its matter counterpart: hydrogen. One of the most interesting transitions for such comparisons is the 1S-2S, since it has been measured with an extraordinary precision in hydrogen [1]. Over the last decades, the development of production and trapping techniques for antihydrogen [2] has enabled studying this transition using two photons from a 243 nm laser [3]. In a very recent experiment, it was shown that antihydrogen can be directly laser cooled [4], and together with the high detection efficiency due to annihilations, this paves the way for ultra-high precision spectroscopy on antihydrogen. I will discuss recent progress in ALPHA to prepare the laser system for such accurate measurements, involving the implementation of a maser and a cesium atomic fountain clock.
[1] C. G. Parthey et al. Improved Measurement of the Hydrogen 1S - 2S Transition Frequency. Phys. Rev. Lett. 107, 203001 (2011).
[2] G. B. Andresen et al. (ALPHA collaboration). Trapped Antihydrogen. Nature 468, 673-676 (2010)
[3] M. Ahmadi et al. (ALPHA collaboration). Characterization of the 1S-2S Transition in Antihydrogen. Nature 557, 71-75 (2018).
[4] C. J. Baker et al. (ALPHA collaboration). Laser cooling of antihydrogen atoms. Nature 592, 35-42 (2021).
