Colloquium: Dr. Steven Jones



Vrije Universiteit, WN-C121, De Boelelaan 1081, 1081 HV Amsterdam

Precision Physics with Antihydrogen – Past, Present, and Future Research

Dr. Steven Jones

Faculty of Science



Precision Physics with Antihydrogen – Past, Present, and Future Research

Precision measurements of antimatter systems are important for understanding the matter-antimatter asymmetry problem, and exploring new physics beyond the Standard Model. In the last decade, groups including the Antihydrogen Laser Physics Apparatus (ALPHA) collaboration at CERN have succeeded in synthesising and trapping cold antihydrogen atoms for extended periods of time [1]. The ALPHA collaboration has since measured the two-photon 1s-2s transition, and the ground state hyperfine splitting of antihydrogen with a fractional precision of 2x10-12 [2] and 4x10-4 [3] respectively, consistent with CPT invariance in both the optical and microwave domains. Recently, the 1s-2p Lyman-α transition has also been observed [4], which marks an important step towards laser cooling of antihydrogen.
Here, I will present an overview of antihydrogen production with the ALPHA apparatus, before discussing the ongoing state-of-the-art measurements, and prospects for improving the precision of these measurements. I will conclude with my research proposal for a source of cold/ultra-cold hydrogen using laser dissociation of BaH+, towards a simultaneous or near-simultaneous measurement of hydrogen and antihydrogen in the same trap. Such a direct comparison would overcome many of the systematic effects that limit the accuracy of antihydrogen spectroscopy.

[1] G. B. Andresen et al. (ALPHA collaboration). Confinement of Antihydrogen for 1,000 Seconds. Nature Physics, 7, 558 (2011).
[2] M. Ahmadi et al. (ALPHA collaboration). Characterization of the 1S-2S Transition in Antihydrogen. Nature 557, 71-75 (2018).
[3] M. Ahmadi et al. (ALPHA collaboration). Observation of the Hyperfine Spectrum of Antihydrogen. Nature 548, 66-69 (2017).
[4] M. Ahmadi et al. (ALPHA collaboration). Observation of the 1S–2P Lyman-Α Transition in Antihydrogen. Nature 561, 211-215 (2018).